Stackable portable electronic device comprising adaptive Bluetooth antenna having two radiation axes

Abstract

The invention relates to an electronic device (HW3) comprising a chassis (10) made of an electrically conductive material and a radio frequency antenna comprising a combination of a closed slot antenna (40, 50) and an open slot parasitic antenna (70, 102). When the rack (10) is outdoor, the open slot parasitic antenna has a tuning frequency within a specified frequency band and the closed slot antenna has a tuning frequency outside the specified frequency band. The closed slot antenna has a tuning frequency within the specified frequency band and the open slot parasitic antenna has a tuning frequency outside the specified frequency band when the gantry (10) faces a front side or conductive surface of a similar device.

Description

Technical Field

[0001] The present invention relates to a hardware wallet for cold storage of private keys from a blockchain. The present invention also relates to the ergonomics of portable electronic devices, and in particular to the ergonomics of hardware wallets for cold storage of private keys. Background Art

[0002] In recent years, the development of cryptocurrencies or other types of crypto assets managed by blockchains, such as non-fungible tokens (NFTs) and smart contracts, has given rise to various ways of storing and keeping private keys attached to these different types of crypto assets. This is how the concepts of "wallets", "cold storage" and "hot storage" of private keys emerged. A "wallet" is a device or program whose function is to manage crypto assets and therefore store the private keys attached to them. So-called "hot wallets" are connected to the Internet and exposed to hacker attacks or viruses and malware. These hot wallets can be wallets managed by centralized exchanges that do not provide the highest level of security. As a result, many centralized platforms have been robbed of hundreds of millions of dollars by hackers over the years. "Hot" wallets can also take the form of programs installed on mobile phones, tablets or personal computers ("software wallets"). Such wallets are permanently connected to the Internet and are therefore themselves subject to attack.

[0003] Cold wallets are the safest solution for cold storage of private keys, i.e. avoiding direct access to the internet, which reduces the risk of attacks and, therefore, the risk of being stolen by hackers. Transactions involving private keys are signed in an offline environment. Any transaction initiated online is temporarily transferred to an offline hardware wallet and then digitally signed there before being sent to the online network. Since the private key is not transferred to the online server during the signing process, hackers cannot access it.

[0004] The simplest form of cold storage is a paper wallet. A paper wallet is a document that has the user's public and private keys written on it. The document usually has a combined QR code that can be scanned to sign transactions. The disadvantage of this medium is that if the paper wallet is lost, illegible, or destroyed, the user can no longer access their funds.

[0005] Hardware wallets are a convenient alternative to paper wallets for storing private keys. In addition, hardware wallets are usually configured to generate a recovery phrase to recover the private keys in case they are lost. It is important to note that crypto assets are never stored in hardware wallets, but are recorded on the blockchain. Hardware wallets only store private keys to manage transactions on the blockchain. The public key corresponding to the private key points to the address on the blockchain where the asset is effectively located.

[0006] like Figure 1As shown, the hardware wallet HW is never directly connected to the Internet. To be able to use it, the hardware wallet HW must be connected to a host device HDV via a data link LNK (e.g., USB or Bluetooth). The host device HDV can be a computer, a mobile phone or a tablet, and runs a so-called "companion" software for conducting transactions on the blockchain BCN, such as the "Ledger live" software developed by the applicant. Alternatively, the hardware wallet HW can be used with a decentralized exchange or DEX through the HDV host device, where users can conduct transactions while keeping their keys.

[0007] The hardware wallets HW sold by the applicant are commercially successful because they provide a high degree of security by using a "secure element" to store private keys and sign transactions. A secure element is a hardware platform that can store and manipulate data in accordance with security rules and requirements set by a trusted authority. It comes in the form of a semiconductor chip that implements various countermeasures against attacks by spoofers.

[0008] Figure 2 The architecture of a hardware wallet HW1 sold by the applicant under the name “Nano S” is shown. The hardware wallet HW1 has a secure element SE1 paired with a microcontroller MCU1. The processor MCU1 has a USB interface U1 and acts as a proxy device for the secure element SE1 for communicating with an external host device HDV running a companion application (see Figure 1 ). The secure element SE1 has its own secure operating system OS (firmware) that allows it to run applications APP, and incorporates a cryptographic coprocessor CRY. The hardware wallet HW1 also has a display DISP1 and two buttons B1, B2.

[0009] The display DISP1 and the buttons B1, B2 are managed by the microcontroller MCU1. These two buttons play an important role in ensuring the security of certain operations: the user must press both buttons simultaneously to prove their consent or permission to perform or complete the operation.

[0010] Figure 3 The architecture of a second hardware wallet HW2, marketed by the applicant under the name “Nano X”, is shown and described in more detail in the “Ledger Nano X Security Target” security information notice published on the website of the French National Agency for Security of Information Systems (ANSSI).

[0011] (https: / / www.ssi.gouv.fr / uploads / 2019 / 10 / anssi-cible-cspn-2019_12en.pdf)

[0012] The hardware wallet HW2 (like the wallet HW1) comprises a secure element SE2, a microcontroller MCU2 with a USB interface U1, a display DISP2 and two buttons B1 and B2. It also has a battery BAT that can be charged via the USB interface and a Bluetooth communication interface BT1 managed by the microcontroller.

[0013] As mentioned before, when performing certain sensitive operations, the user must press two buttons simultaneously to express their consent or permission, as described in the aforementioned document “Ledger Nano X Security Target”, paragraph 1.2 “Terms”, line “Permission”. The security concept of Ledger Nano X is reinforced by the end user. Once a sensitive operation is required, the end user must confirm the operation using these two buttons.

[0014] Unlike the hardware wallet HW1, the display DISP2 and buttons B1, B2 of the hardware wallet HW2 are managed directly by the secure element SE2, which provides an additional degree of security in the event of damage to the microcontroller MCU2. Therefore, the signal received by the secure element SE2 indicating that the user is pressing the two buttons B1 and B2 at the same time cannot be tampered with by the microcontroller. Similarly, the information presented to the user by the screen DISP2, such as the amount of the transaction that must be verified by the user, cannot be forged.

[0015] In summary, in a hardware wallet for cold storage of private keys within the meaning of this application, the microcontroller associated with the secure element does not execute any application and has the sole function of managing communication devices, USB, Bluetooth, etc. and other peripherals (battery, battery charger, etc.). All applications are run by the secure element.

[0016] In addition, there is a conventional architecture in Figure 4 The device DV1 shown in the figure comprises a microcontroller SMCU with a trust zone TZ. The trust zone TZ may in some cases be associated with a secure element SE to which it delegates the most sensitive operations or cryptographic calculations. The specific implementation of this trust zone TZ is typically based on the use of two virtual processors combined with hardware access control. This allows the core of the application to switch between two states, called "worlds", in order to prevent information from leaking from the most trusted world to the least trusted world. While using the same core, each world can operate independently of each other. The memory and the device are then informed of the operating world of the kernel and can use it to provide access control to the secrets and code of the device. Typically, the microcontroller SMCU runs a so-called "rich" operating system ROS in the least secure world, and a smaller security-specific code in the most secure world to reduce exposure to attacks. The rich operating system is typically Android.

[0017] This type of device does not need to be attached to a host device to perform operations on the blockchain and typically includes a Wi-Fi communication interface WF1 in addition to the USBU1 and Bluetooth BT1 communication interfaces. Due to the rich operating system of this device, it offers a wide range of features and very advanced ergonomics, including a large touch screen like those found in smartphones. In some cases, the device DV1 can be equipped with mobile phone circuitry and form a fully fledged mobile phone equipped with private key storage features.

[0018] In practice, although such a device DV1 offers undeniable ergonomic advantages, it is not immune to attacks and does not meet the same stringent security requirements as a hardware wallet for cold storage of private keys, which has no internet connection and whose microcontroller never executes an application.

[0019] On the other hand, hardware wallets for cold storage of private keys offer only poor ergonomics, which makes some transactions difficult to carry out due to the small display and the requirement to provide two buttons to authenticate certain sensitive operations.

[0020] Therefore, there may be a need to improve the ergonomics of hardware wallets without changing the high level of security they provide.

[0021] Additionally, some crypto-asset holders use multiple hardware wallets to store crypto-assets of different types or values. For example, a user may use a first hardware wallet dedicated to managing crypto-assets of low monetary value to perform daily transactions or pay for purchases, a second hardware wallet dedicated to managing crypto-assets of high monetary value, and a third hardware wallet dedicated to managing crypto-assets such as non-fungible tokens. Therefore, for users who use several such wallets, it may also be desirable to improve the ergonomics of the hardware wallets.

[0022] More generally, it may be desirable to provide improvements applicable to portable electronic devices, and in particular to hardware wallets for storing private keys, which improvements improve their ergonomics, or provide new functionalities, or improve their performance in terms of Bluetooth communication when equipped with Bluetooth communication means. Summary of the invention

[0023] An embodiment relates to an electronic device, comprising: a frame of conductive material, the frame comprising a front side, a rear side, a side wall, and a conductive plate located on the front side of the frame; a radio frequency antenna, the radio frequency antenna being designed to send or receive data in a specified frequency band; and a wireless communication circuit, the wireless communication circuit being configured to provide a radio frequency signal to the radio frequency antenna. According to the present invention, the radio frequency antenna includes a combination of a closed slot antenna and an open slot parasitic antenna, the closed slot antenna is made in the side wall of the rack and has a radiation axis substantially perpendicular to the side wall of the rack, and the open slot parasitic antenna has a radiation axis substantially perpendicular to the radiation axis of the closed slot antenna, and the conductive plate forms a first shield for radiation emitted by the open slot parasitic antenna; the closed slot antenna and the open slot parasitic antenna are configured so that: when the rack is outdoors, the open slot parasitic antenna has a tuning frequency within the specified frequency band, while the closed slot antenna has a tuning frequency outside the specified frequency band, and when the rear side of the rack is opposite to the front side of a similar device or a conductive surface that forms a second shield for radiation emitted by the open slot parasitic antenna, the closed slot antenna has a tuning frequency within the specified frequency band, while the open slot parasitic antenna has a tuning frequency outside the specified frequency band.

[0024] According to one embodiment, the closed slot antenna includes a longitudinal port made in the side wall of the frame and traversing the side wall, the longitudinal port including a first longitudinal surface and a second longitudinal surface facing each other; and a device for applying a ground voltage to the first surface of the longitudinal port and applying a radio frequency signal to the second surface of the longitudinal port, and the open slot parasitic antenna includes a conductive arm parallel to the longitudinal port and arranged near the longitudinal port, the conductive arm having a free end and an end electrically connected to the side wall of the frame.

[0025] According to one embodiment, the connection end of the arm is electrically connected to the side wall of the housing near an end of the second surface of the longitudinal port that receives the radio frequency signal.

[0026] According to one embodiment, the length and height of the longitudinal port, the length of the conductive arm, and the orthogonal distance between the conductive arm and the side wall of the rack are configuration parameters of the closed slot antenna and the open slot parasitic antenna, and wherein the closed slot antenna and the open slot parasitic antenna form a resulting antenna whose gain in the specified frequency band is greater than -5dB when the rack of the equipment is outdoors and remains greater than -5dB when the back side of the rack faces a conductive surface.

[0027] According to one embodiment, the closed slot antenna and the open slot parasitic antenna are configured such that when the rear side of the chassis faces a conductive surface, radiation from the closed slot antenna dominates radiation from the open slot parasitic antenna.

[0028] According to one embodiment, the length of the longitudinal port is close to one quarter of the wavelength of a radio frequency signal at a frequency of 2.4 GHz, or about 30.6 mm to within a few millimeters or tenths of a millimeter to account for the presence of open slot parasitic antennas.

[0029] According to one embodiment, the housing is made of an electrically conductive, non-magnetic material and has magnets for magnetically stacking the device with similar devices.

[0030] According to one embodiment, the device includes an RF signal injector, which includes: two substantially parallel flat electrodes connected by a connecting portion, the first electrode resting on a first surface of the longitudinal port, and the second electrode resting on a second surface of the longitudinal port; and a compression portion of a flexible material and an elastic material, which is arranged between the two electrodes and applies an expansion force on the two electrodes, which presses the first electrode against the first surface of the longitudinal port and the second electrode against the second surface of the longitudinal port.

[0031] According to one embodiment, the two electrodes have a large contact surface with the surface of the longitudinal port, the length of which is at least equal to one quarter of the length of said surface.

[0032] According to one embodiment, a radio frequency signal injector includes an electrical conductor connecting a first electrode and a second electrode and an electronic component.

[0033] According to one embodiment, the conductive arm includes a base attached to the side wall of the frame, the base serving as an extension of the end of the conductive arm electrically connected to the side wall of the frame, and the conductive arm also includes a protruding contact portion resting on a contact surface provided in the side wall of the frame.

[0034] According to one embodiment, the conductive arm is mounted between its base attached to the side wall of the frame and a protruding contact portion resting on a contact surface provided in the side wall of the frame in a state of elastic deflection, the elastic deflection applying pressure to the protruding contact portion resting on the surface of the frame contact portion.

[0035] According to one embodiment, the conductive arm is arranged in a guide member of plastic material, thereby ensuring the parallelism of the arm relative to the side wall of the frame.

[0036] According to one embodiment, the device forms a hardware wallet for cold storage of cryptographic keys of a blockchain and includes a microcontroller and a secure element.

[0037] According to one embodiment, the designated frequency band is a Bluetooth frequency band or a Wi-Fi frequency band.

[0038] The embodiment also provides a method for improving the performance of a radio frequency antenna designed to send or receive data in a specified frequency band, the antenna being arranged in an electronic device, the electronic device comprising a frame of a conductive material and a wireless communication circuit configured to provide a radio frequency signal to the radio frequency antenna, the frame comprising a front side, a rear side, a side wall, and a conductive plate on the front side of the frame. According to the present invention, the radio frequency antenna includes a combination of a closed slot antenna and an open slot parasitic antenna, the closed slot antenna being made in the side wall of the rack and having a radiation axis substantially perpendicular to the side wall of the rack, and the open slot parasitic antenna having a radiation axis perpendicular to the radiation axis of the closed slot antenna; the conductive plate forms a first shield for radiation emitted by the open slot parasitic antenna; the closed slot antenna and the open slot parasitic antenna are configured so that: when the rack is outdoors, the open slot parasitic antenna has a tuning frequency within the specified frequency band, while the closed slot antenna has a tuning frequency outside the specified frequency band, and when the rear side of the rack is opposite to the front side of a similar device or a conductive surface forming a second shield for radiation emitted by the open slot parasitic antenna, the closed slot antenna has a tuning frequency within the specified frequency band, while the open slot parasitic antenna has a tuning frequency outside the specified frequency band.

[0039] According to one embodiment, the closed slot antenna includes a longitudinal port made in and across the side wall of the frame, the longitudinal port including a first longitudinal surface and a second longitudinal surface facing each other; and a device for applying a ground voltage to the first surface of the longitudinal port and applying a radio frequency signal to the second surface of the longitudinal port, and has a radiation axis substantially perpendicular to the side wall of the frame, and the open slot parasitic antenna is made by arranging a conductive arm parallel to and close to the longitudinal port, the conductive arm having a free end and an end electrically connected to the side wall of the frame.

[0040] According to one embodiment, the method includes the step of connecting the end of the arm to the side wall of the housing near an end of the second surface of the longitudinal port that receives the radio frequency signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The following non-limiting exemplary embodiments of the improvement of the portable device are described in conjunction with the accompanying drawings, including:

[0042] Figure 1 shows a general example of hardware wallet usage via a host device,

[0043] Figure 2 shows a conventional hardware wallet architecture,

[0044] Figure 3 Another conventional hardware wallet architecture is shown.

[0045] Figure 4 shows a conventional electronic device architecture that provides a moderate level of security,

[0046] Figure 5 shows a high-level hardware wallet architecture,

[0047] Figure 6 Shows Figure 5 The organization of the non-volatile memory part of the hardware wallet,

[0048] Figure 7 Shows Figure 5 Examples of hardware wallet usage:

[0049] Figure 8 Is described when used Figure 5 Flowchart of the process of protecting certain operations with a hardware wallet.

[0050] Fig. 9 Shows Figure 5 Hardware wallet implementation plan,

[0051] Fig.10 Describes the test Fig. 9 The steps of the components shown in

[0052] Fig.11 yes Figure 5 A top view and a perspective view of an embodiment of a hardware wallet,

[0053] Fig.12 yes Fig.11 Bottom and perspective views of the hardware wallet.

[0054] Fig.13 yes Fig.11 A cross-sectional diagram of a hardware wallet showing some of the building blocks,

[0055] Fig.14 yes Fig.11 Another cross-sectional diagram of a hardware wallet showing the other building blocks,

[0056] Fig.15 yes Fig.11 Top view of a hardware wallet display.

[0057] Fig.16 yes Fig.11 Top view of the touch module of the hardware wallet.

[0058] Fig.17 yes Fig.11 Top view of the protective layer of the hardware wallet.

[0059] Fig.18 Shown for Fig.11 Hardware wallet cover,

[0060] Fig.19 is a cross-sectional view of a magnetic stackable hardware wallet including a magnet,

[0061] Fig. 20 yes Fig.19 Bottom view of the hardware wallet.

[0062] Fig.21 It's from below. Fig.19 An exploded view of the hardware wallet.

[0063] Fig. 22 is an abstract representation of the arrangement of magnets in the housing of a portable electronic device,

[0064] Fig.23 shows the dimensions of the magnet,

[0065] Fig.24 is a cross-sectional diagram of the magnetic stack of a hardware wallet,

[0066] Fig.25 is a cross-sectional view of a variation of a magnetic stackable hardware wallet,

[0067] Fig.26 is a cross-sectional view of another variation of a magnetic stackable hardware wallet,

[0068] Fig. 27 The magnetic stack of hardware wallets is shown,

[0069] Fig.28 shows an example of a menu displayed by a hardware wallet stacked with other hardware wallets,

[0070] Fig.29 describes the operations performed by a hardware wallet stacked with other hardware wallets,

[0071] Fig.30 is a cross-sectional diagram of a stack of hardware wallets equipped with sensors.

[0072] Fig.31 A method for automatically managing a stack of hardware wallets is described,

[0073] Fig.32 Another example of an on-screen menu of a hardware wallet stacked with other hardware wallets is shown,

[0074] Fig.33 Describes the process for manually managing a stack of hardware wallets,

[0075] Fig.34 is an exploded view of the hardware wallet including the antenna,

[0076] Fig.35 yes Fig.34 A front view of the hardware wallet showing the antenna elements,

[0077] Fig.36 is a top view of another antenna element,

[0078] Fig.37 is a bottom view of another antenna element,

[0079] Fig.38 yes Fig.34 A cross-sectional diagram of a hardware wallet.

[0080] Fig.39 yes Fig.34 Cross-section and perspective diagram of a hardware wallet.

[0081] Fig.40 yes Fig.36 , Fig.37 Electrical diagram of the antenna element,

[0082] Fig.41 yes Fig.34 An equivalent diagram of a portion of a hardware wallet antenna,

[0083] Fig.42 and Fig.43 yes Fig.34 Bottom and perspective views of the hardware wallet.

[0084] Fig.44 Shows Fig.42 , Fig.43 The antenna elements present in

[0085] Fig.45 exists in Fig.34 Equivalent diagram of the antenna in the hardware wallet,

[0086] Fig.46 , Fig.47 Shows Fig.45 The characteristics of the antenna in two different uses,

[0087] Fig.48 Shown is a stack of two hardware wallets.

[0088] Fig.49A , Fig.49B , Fig.50A and Fig.50B Shows Fig.45 Other characteristics of the antenna in two different uses. DETAILED DESCRIPTION

[0089] Improvements to hardware wallets for cold storage of private keys are described below. Some improvements may be implemented in all types of portable electronic devices, and therefore have applications far beyond a single manufacture of hardware wallets.

[0090] Example of a hardware wallet with a touchscreen controlled by a secure element

[0091] As mentioned above, a secure element is a hardware platform that implements various countermeasures to prevent attacks by spoofers.

[0092] Illustratively, attacks may include:

[0093] - Inspection and / or reverse engineering attacks (grinding, layer removal, thermal imaging, X-ray, scanning electron microscopy),

[0094] - a side-channel attack (analysis of power consumption, electromagnetic radiation, computation time, or any other measurable physical quantity that correlates with the secret value the attacker is trying to discover), or

[0095] - Fault injection attacks using lasers or test spikes (for example, injecting parasitic or "false" signals on power lines, clock lines, or data buses).

[0096] There are many countermeasures provided in the secure element. Some are software, while others are hardware (code to prevent attacks, protection of volatile and non-volatile memories, means to mask power consumption, data desensitization, means to mask the topology of the integrated circuit, voltage sensors, frequency sensors, light sensors, temperature sensors, allowing the detection of attacks, etc.). In the event of an attack, the operating system of the secure element is designed to initiate defensive actions, such as interrupting the ongoing calculation, permanently blocking the circuit or self-destructing by completely erasing its memory.

[0097] Due to the many countermeasures they implement, security elements are complex and expensive to manufacture. As a result, the functionality they offer is limited, in particular when it comes to the number of input / output sections they offer. Security elements are therefore not usually used to control screens, and when they do control a screen, as in the product "NanoX" marketed by the applicant, it is to control a small screen without any touch-sensitive functionality.

[0098] Thus, considering the commercially available security elements, and in particular those providing a security level at least equal to 5 at the Evaluation Assurance Level (EAL), which corresponds to level E4 of the European Information Technology Security Evaluation Standard (ITSEC) and level B2 of the American Trusted Computer System Evaluation Standard (TCSEC), the Applicant is not aware of any security element having more than 10 input / outputs to date. In fact, the higher the number of IOs, the greater the attack exposure of the security element.

[0099] It should be noted here that "IO" refers to a 1-bit digital port that can be used to send or receive logic signals. The number of IOs is less than the number of electrical pins of the security element, which includes power pins, ground pins, and possible reset pins in addition to IO pins.

[0100] However, in this improved case, it has been found possible to utilize a secure element to manage the touch screen. In fact, a secure element with 10 IOs can handle the following serial links:

[0101] 1) ISO / IEC 7816 link, which has only three logic signals CLK (clock), I / O (data) and RST (reset);

[0102] 2) SPI (Serial Peripheral Interface) bus using only 4 signals:

[0103] - SCLK (serial clock) (generated by the master device),

[0104] -MOSI (Master Output, Slave Input),

[0105] -MISO (Master In, Slave Out), and

[0106] -SS(from select);

[0107] 3) The I2C bus (Inter-Integrated Circuit bus) which has only two signals:

[0108] -SDA (serial data line): bidirectional data line,

[0109] -SCL (Serial Clock Line): bidirectional synchronous clock line,

[0110] That is, a total of 9 IOs are required.

[0111] It has also been found that a certain type of display and a certain type of touch module can be controlled using an SPI bus or an I2C bus. The secure element and the microcontroller can also be connected via an ISO / IEC 7816 smart card link or an SPI, I2C, USB link, etc.

[0112] Finally, managing the touch screen requires processing an interrupt signal emitted by the touch screen whenever a touch event is detected. This interrupt signal activates the touch event processing routine. Therefore, the reception of this signal requires mobilizing another I / O of the security element, that is, a total of 10 IOs. Therefore, in this improved case, it has been found that it is not impossible to control the touch screen using a security element.

[0113] Thus, according to an initial improvement, a hardware wallet is provided, comprising a touch screen controlled exclusively by a secure element via one or more serial links. According to certain precautions to be elaborated below, such a touch screen can significantly improve the comfort of the user interface while meeting the security requirements applicable to hardware wallets. According to this improvement, the touch screen has a diagonal greater than or equal to 3 inches (i.e., 7.62 cm, one inch equals 2.54 cm), but preferably greater than or equal to 3.5 inches (i.e., 8.89 cm), and has at least 600×400 pixels. In one embodiment, the screen has a diagonal of 3.9 inches (9.906 cm) and has 670×496 pixels.

[0114] Hardware wallet hardware implementation example

[0115] Figure 5 The general architecture of the hardware wallet HW3 according to the improvement is shown. The device HW3 includes a security element SE3, a microcontroller MCU3 and a touch screen TS. The touch screen TS includes an E-Ink display EID and a touch module TM. The touch screen TS is under the exclusive control of the security element SE3. To this end, the I / O resources of the security element SE3 are divided into three I / O groups: IOGA, IOGB, IOGC. The I / O group IOGA is allocated to implement the bus BS1, which connects the security element SE3 to the microcontroller MCU3. The I / O group IOGB is allocated to implement the bus BS2, which connects the security element SE3 to the display EID, and the I / O group IOGC is allocated to implement the bus BS3, which connects the security element SE3 to the touch module TM. Bus BS1 is, for example, an IEC / ISO 7816 bus, bus BS2 is, for example, an SPI bus and bus BS3 is an I2C bus. The opposite arrangement can be provided, in which BS2 is an I2C bus and BS3 is an SPI bus, or another serial link protocol compatible with the resources of the security element. The SPI bus is provided on the display EID side by a chip integrated into the display EID (such as UC8177). The I2C bus is managed on the Touch ModuleTM side by chips integrated into it (e.g. GT1151QM chip) management. Security elements such as the ST33K1M series chip, and the microcontroller is the STM32 series chip.

[0116] The device HW3 also includes various peripherals controlled by the microcontroller MCU3, such as:

[0117] -Battery BAT;

[0118] - Power management IC PMIC, such as NXP PCA9420 chip. The circuit PMIC receives the voltage Vat from the battery when the battery is charged, supplies the voltage Vat to the battery when the battery needs to be charged, and provides the regulated supply voltage Vdc to the microcontroller MCU3, the security element SE3 and the touch screen TS;

[0119] -Antenna QiA for inductive battery charging according to Qi technology (https: / / www.wirelesspowerconsortium.com / qi / ). Antenna QiA is connected to a wireless charging integrated circuit (WCIC), such as 103AHQI01 chip. Circuit WCIC provides voltage Vqi to circuit PMIC for battery charging;

[0120] - USB port U1. The USB port provides a voltage Vusb to the circuit PMIC for battery charging, provides data DTu received from an external device connected to the USB port to the microcontroller MCU3, and transmits the data DTu to the external device;

[0121] - A Bluetooth antenna BTA which receives a radio frequency signal RFS provided by a circuit BTM for managing Bluetooth communications. Although represented as a block separate from the microcontroller MCU3, the circuit BTM may be included in the microcontroller MCU3. The circuit BTM provides data DTb exchanged with an external device via a Bluetooth link or sends data DTb to an external device via a Bluetooth link.

[0122] The device HW3 thus has the advantage of having a touch screen that is exclusively controlled by the secure element SE3 and therefore does not suffer damage even in the event of an attack on the microcontroller MCU3. The latter does not run any application and does not store any cryptographic secrets used by the secure element. It only manages peripherals and acts as a proxy processor with respect to the secure element, sending to it data DTb, DTu received by the communication interface selected by the user, or sending to external devices data DTb, DTu provided by the secure element. The device HW3 thus does not offer any possibility of direct connection to the Internet and, despite its touch screen, retains a hardware wallet for cold storage of private keys, thus offering a high level of security.

[0123] The secure element SE3 also includes a memory space MEM, which includes a read-only memory area (ROM memory), a programmable and electrically erasable non-volatile memory area (flash memory) and a volatile memory area (RAM). The programmable and electrically erasable non-volatile memory area receives an operating system OS3 from the secure element. The OS is configured to allow the touch screen TS to be used by applications.

[0124] Hardware wallet software implementation example

[0125] Combining the example of the hardware architecture just described, Figure 6 An example of the organization of a programmable and electrically erasable non-volatile memory area of ​​a memory space MEM is schematically shown. The memory space MEM includes an area APP for storing applications APP1, APP2, ... APPn and an area for receiving an operating system OS3. The operating system OS3 includes a privileged application memory area PAP for storing a dashboard DB for privileged applications, and an operating system module memory area OSMD for storing operating system modules. The memory area OSMD includes:

[0126] -User Interface Management Module USINT,

[0127] - Equipment customization module PERS,

[0128] - a cryptographic module CRY combined with a cryptographic coprocessor integrated into the secure element or a hardware accelerator for advanced cryptographic functions,

[0129] - Authentication and Application Attestation Module EAA,

[0130] - An IO management module IOM, wherein the IO management module IOM is used to manage the communication interface.

[0131] According to this improvement, the memory area OSMD also includes a graphics engine GENG configured to manage the electronic ink display EID. The GENG graphics engine includes:

[0132] - pre-configured pages PG,

[0133] - Pre-configured layouts,

[0134] - pre-configured objects OB, and

[0135] -The basic form of BF.

[0136] Therefore, application access to the EID Viewer is under the control of the secure element's OS3 operating system, which first verifies the authenticity and legitimacy of the programs before making the graphics engine available to them.

[0137] According to this improvement, the memory area OSMD also comprises a touch management engine TME which provides authorized applications with the possibility of accessing and interpreting information emitted by the touch module TM.

[0138] The graphic engine GENG also includes an event management engine EVENG which receives touch information provided by the touch engine TME and searches for correlation with a display area to distinguish between an invalid tap and a valid tap on the screen by a user.

[0139] In an embodiment in which the limited resources of the security element are reserved in terms of random access memory (RAM), the graphics engine GENG operates without RAM allocation. Image pixels are transferred to the RAM in the display without reloading them. In another embodiment that can be combined with the previous embodiment, the graphics engine GENG does not process preconfigured pages PG, preconfigured layouts LY, and preconfigured objects OB. Therefore, the "work" implemented by the operating system is minimized and limited to the basic form BF, because it does not need to dynamically create objects. The processing of complex shapes is left to the application, whose code is designed with preconfigured graphic elements that minimize the operations that the graphics engine must perform.

[0140] Figure 7 An example of use of a hardware wallet HW3 is shown. Since the wallet cannot be directly connected to the Internet, a connection is established with a host device HDV connected to the Internet (“WB”) and running a companion application CA such as the “Ledger Live” application (https: / / www.ledger.com / fr / ledger-live). The device HW3 can then interact with the companion software to trade on the blockchain BCN or the decentralized exchange DEX.

[0141] The hardware wallet HW3 is also managed by a transaction black box (i.e., a hardware security module HSM) located in a data center, to which the hardware wallet HW3 is connected via a secure HTTPS link. The transaction black box does not store any private keys and only ensures the verification of the authenticity of the device, its debugging, the updating of its operating system, the downloading of certified applications, etc.

[0142] Includes implementation to authenticate sensitive transactions via two virtual buttons

[0143] While the secure use of a touch screen controlled exclusively by a secure element offers certain ergonomic advantages, abandoning the two conventional buttons whose simultaneous pressing ensures certain sensitive operations may prove detrimental to the security of the device.

[0144] Therefore, in one embodiment, the operating system is configured to emulate the two hardware buttons of the prior art through the touch screen. Figure 8 As an example, the following example illustrates the execution of sensitive operations that must ensure user approval:

[0145] - At step S1 , the device HW3 connects to the companion application CA or the HSM module depending on the type of operation to be performed, such as performing a transaction through the companion application CA or displaying a recovery phrase, activating and configuring the device, or downloading an application through the HSM, etc.

[0146] - at step S2, the device HW3 initiates the execution of a sensitive operation,

[0147] - At step S3, the device HW3 displays on the display EID a request for confirmation by the user that the sensitive operation may be performed and waits for confirmation.

[0148] The confirmation wait comprises a step S31 in which the device HW3 displays on the display EID at least two virtual buttons, preferably far apart. These buttons may have any graphic or fancy graphics chosen by the designer. This step is followed by a waiting phase S32 in which the device HW3 reads the information provided by the touch module TM in a loop within a time T. Before the time T expires, if the device HW3 detects two simultaneous presses of the user on two buttons at step S33, the device then performs (or completes) the operation at step S4. When the time T expires, if the device HW3 finds at step S34 that the user has not submitted the operation, the device cancels the operation at step S5.

[0149] Example embodiments of hardware wallets with certain types of peripheral components that impose specific constraints

[0150] As mentioned above, commercially available certified security elements only provide a small number of input / outputs, usually up to 10 input / outputs. In practice, security elements are usually designed to be included in smart cards or objects connected to the Internet to protect the Internet of Things, especially in professional applications. Security elements with only 10 input / outputs are therefore not designed to drive large touch screens (other electrical pins in the security element, such as power pins or ground pins, are not considered as input / outputs as described above).

[0151] Thus, in the above, the following usage of the resources of the secure element has been proposed as an example:

[0152] - Two input / output sections (SDA, SCL signals) for managing the I2C bus connected to the Touch Module TM,

[0153] - Four input / output sections of the SPI bus for managing the display EID (SCLK, MOSI, MISO, SS),

[0154] - Three input / output sections (I / O, CLK and RST) for managing the ISO / IEC 7816 bus between the secure element and the microcontroller.

[0155] In addition to these 9 input / output sections, another input / output section of the security element is reserved for receiving an interrupt signal issued by the touch module TM when a touch event is detected to place the security element in a touch event processing routine. Under these conditions, all 10 input / output sections of the security element are used.

[0156] However, in some embodiments, the display EID may include a configuration component that needs to be set up and is only accessible via a dedicated serial link to the component. Fig. 9 As shown, the display EID may include, for example, a display module EID0 and a configuration component WM of the display module EID0. The configuration component WM is, for example, a programmable and electrically erasable non-volatile memory that receives a waveform library, which is connected to the display module EID0 through an internal circuit. The configuration component WM has its own input / output section compatible with the SPI bus.

[0157] Because the security element SE3 accesses the configuration device WM to program or delete data therein, the bus BS2 is used to control both the display module EID0 and the configuration component WM. In particular, the bus BS2 wires that transmit the SCLK, MOSI and MISO signals are connected to the input / output parts of both the display module IED0 and the configuration component WM. The SS signal of the bus BS2 is only applied to the chip select input CSEL1 of the display module EID0, and the SS signal applies the selection signal SEL1 to the chip select input CSEL1.

[0158] In summary, Fig. 9 The I / O assignment of the safety element SE3 shown in Figure 1 is as follows:

[0159] 1) Bus BS1 (ISO / IEC 7816), IOGA I / O group:

[0160] an input / output part IO1 of the secure element SE3 for managing the signal RST and connected to an input / output part IOM1 of the microcontroller MCU3,

[0161] an input / output part IO2 of the secure element SE3 for managing the signal CLK and connected to an input / output part IOM2 of the microcontroller MCU3,

[0162] an input / output part IO3 of the secure element SE3 for managing the signal RST and connected to an input / output part IOM3 of the microcontroller MCU3,

[0163] 2) Bus BS2 (SPI), IOGB I / O group:

[0164] an input / output IO4 of the secure element SE3 for managing the MISO signal and connected both to an input / output of the display module EID0 and to an input / output of the configuration component WM of the display module EID0,

[0165] the input / output IO5 of the secure element SE3 is used to manage the MOSI signal and is connected both to the input / output of the display module EID0 and to the input / output of the configuration component WM of the display module EID0,

[0166] the input / output IO6 of the secure element SE3 is used to manage the SCLK signal and is connected both to the input / output of the display module EID0 and to the input / output of the configuration component WM of the display module EID0, and

[0167] the input / output section IO7 of the security element SE3 is used for managing the signal SEL1 and is connected only to the input section CSEL1 of the display module EID0 to which it supplies the selection signal SEL1,

[0168] 3) Bus BS3 (I2C), IOGC I / O group:

[0169] - the input / output part IO8 of the security element SE3 is used to manage the SCL signal and is connected to the input / output part of the touch module TM, and

[0170] - the input / output part IO9 of the secure element SE3 is used to manage the SDA signal and is connected to the input / output part of the touch module TM,

[0171] 4) Finally, the last input / output part IO10 of the secure element SE3 is used to receive an interrupt signal sent by the touch module TM, here represented by the reference ITR.

[0172] Since both the configuration component WM and the display module EID0 are connected to the same bus BS2, one is active while the other is disabled, and vice versa, otherwise the secure element cannot communicate with either of them. To this end, the configuration component WM also includes a chip select input CSEL2 for the selection signal SEL2.

[0173] In this case, it therefore appears that the secure element SE3 does not have sufficient input / outputs to generate the selection signal SEL2 for the input CSEL2 of the configuration component WM.

[0174] In one embodiment, a method is implemented to still be able to control the touch screen through the security element SE3. According to the method, the selection input part CSEL2 is controlled by the input / output part IOM4 of the microcontroller MCU3 that provides the selection signal SEL2. This is because, unlike the security element, the microcontroller usually has an available I / O. The binary value of the signal SEL2 provided by the input / output part IOM4 of the microcontroller is controlled by the security element SE3, and the security element SE3 transmits commands to the microcontroller via the bus BS1 for this purpose. The microcontroller is configured to execute these commands "in large quantities". Preferably, it does not have any application that can control the input / output part IOM4 except for the application required to execute the commands transmitted by the security element.

[0175] exist Fig.10 An example of a method for controlling an input CSEL2 of a configuration component WM by a secure element SE3 via a microcontroller MCU3 is described in .

[0176] At step S01, the safety element SE3 transmits a command to select the configuration component WM to the microcontroller MCU3. At step S02, the microcontroller executes the command and applies the selection signal SEL2 of the configuration component to the input CSEL2 via its input / output part IOM4. The value of the signal can be 0 (ground voltage) or 1, depending on the specification provided by the manufacturer of the configuration component WM. At step S03, the microcontroller confirms to the safety element that the configuration component has been selected. At step S04, the safety element SE3 establishes communication with the configuration component WM through the bus BS2 after previously invalidating the input CSEL1 of the display module EID0 by the signal SEL1. The safety element then performs the target operation on the configuration component, such as deleting and / or writing data if it is a non-volatile memory. Once the operation is completed, at step S05, the safety element transmits a command to the microcontroller to cancel the selection of the configuration component WM. At step S06, the microcontroller cancels the selection of the configuration component WM, and then confirms the cancellation to the safety element at step S07. Then, after reselecting the display module EID0 by the signal SEL1 via the input CSEL1 of the display module EID0, the secure element can reestablish communication with the display module EID0 via the bus BS2.

[0177] It will be clear to a person skilled in the art that the method just described may have various alternatives, in particular with regard to the command execution confirmation (which may be optional) and the command transmission protocol between the secure element and the microcontroller.

[0178] Moreover, it will be clear to those skilled in the art that the method can be applied to various other peripheral components. In one embodiment, in addition to display module EID0 and configuration component WM, bus BS2 is also connected to a third peripheral device. The safety element selects / deselects the third device via another I / O of the microcontroller, and after deselecting display module EID0 and configuration component, communicates with the device through data bus BS2.

[0179] Finally, it will be clear to a person skilled in the art that the method can have various applications and is not limited to the control of a touch screen. It can be any circuit structure combining a microcontroller and a security element, wherein the number of peripheral components controlled by the security element is greater than the number of peripheral components it can control when managing all the inputs or input / outputs of these peripheral components (including their selection inputs).

[0180] Example embodiment of a hardware wallet with a large touch screen and frame edge display

[0181] Fig.11 and Fig.12 A frame 10 of a hardware wallet HW3 according to a second improved construction is shown. Fig.11 The front side FS of the slave device HW3 and Fig.12 The frame of the device HW3 is seen from the rear side RS of the device HW3. The frame 10 is a one-piece rectangular part made of machined or die-cast aluminum. It comprises a first longitudinal side wall 101, a second longitudinal side wall 102, a first transverse side wall 103, a second transverse side wall 104 and a plate 105 covering the entire front side FS thereof. Inside the frame, the battery BAT has a printed circuit 11 that receives the various components of the device HW3, the architecture of which has already been described with respect to FIG. Figure 5 Described.

[0182] Fig.13 and Fig.14 1 is a cross section of the device HW3, wherein the rear side RS of the frame faces upward. The device HW3 comprises a touch screen 20 (previously designated as TS) arranged on the front plate 105 of the frame. The touch screen 20 is assembled by an electronic ink display 21 (previously designated as EID) Fig.15 ) is obtained by the touch module 22 (previously designated as TM) Fig.16 ) is covered, and the touch module itself is covered by a protective layer 23 ( Fig.17 )cover.

[0183] Fig.15The display 21 is shown in more detail in FIG. It comprises an active area or display area 211, a painted frame 212, and is manufactured on a soft substrate 213 according to COP (chip on plastic) technology. The display is for example an organic active matrix electrophoretic display, which combines source drivers, gate drivers and an IC controller directly bonded to the display substrate, such as UC8177 controller. The display provides 670×496 pixels with a pixel pitch of 119 microns and 16 gray levels. Its dimensions are, for example, 3.9 inches (9.906 cm), a total length of 77.4 mm, and a total width of 81.7 mm. The dimensions of the active area are, for example, 79.73×59.03 mm. The flexible substrate 213 extends beyond the active area 211 and accommodates row and column multiplexers 214. It is extended by an SPI bus connector 215 made in the flexible printed circuit board, allowing the display 21 to be connected to the printed circuit board 11 in the rack. The connector includes an auxiliary component 216 and a non-volatile memory 217 for receiving a waveform library, which corresponds, for example, to Fig. 9 The configuration component WM mentioned in the implementation scheme of the device HW3.

[0184] Touch module 22 Fig.15 It has a cover area 220 and a painted frame 221, and is made entirely on a flexible printed circuit (FPC) board 222. The cover area 220 includes a touch area 220a and a non-touch area 220b. The flexible board 222 has a receiving module control chip 225 (such as GT1151QM chip). The end of the extension 224 receives an I2C bus connector 226 to connect the touch module 22 to the PCB 11 present in the chassis. The touch module has, for example, a total length of 65.7 mm and a total width of 81.3 mm. For example, the touch area 220a has a surface area of ​​79.73×48.10 mm, and the non-touch area 220b extends beyond the touch area by 34.0 mm.

[0185] Fig.17 23. It has a transparent area 230 and a painted frame 231. For example, the layer has a total length of 67.9 mm and a total width of 83.7 mm. The layer includes a moisture barrier, an anti-reflective hard layer and an optically clear adhesive on its back to assemble it on the touch module 22. In one embodiment, the layer is designed to be scratch-resistant ( Fig.24 ).

[0186] exist Fig.13 and Fig.14In FIG. 1 , it can be seen that the longitudinal side wall 101 of the frame has a rounded outer edge 101r with a substantially semi-circular cross-section indicated by the dashed arrow. Due to its thickness, the wall 101 also has a flat portion extension plate 105, which forms part of the front side FS of the frame. Behind the rounded edge 101r, it also has a flat portion, which forms part of the rear side RS of the frame. The rest of the rear side of the frame is closed by a cover 110. It should be noted that in FIG. Fig.18 In the illustrated embodiment of the cover, the cover 110 has an antenna coil connected to the circuit board 11 .

[0187] According to the improvements described herein, and as Fig.13 As shown, the active area 211 of the display 21 extends over the following areas:

[0188] - a large part of the front plate 105,

[0189] - a large part of the flat part of the wall 101 which extends the plate 105 and forms part of the front side of the frame,

[0190] - a large part of the rounded edge 101r of the wall 101, and optionally

[0191] - A flat portion of the wall 101 which forms part of the rear side of the frame.

[0192] A flexible substrate 213 extending beyond the active area 211 penetrates the chassis to allow an SPI bus connector 215 to be attached to the PCB 11 , this portion of the circuit being hidden by the cover 110 .

[0193] Similarly, in Fig.14 In FIG. 1 , the touch module 22 covering the display 21 and itself covered by the layer 23 extends over the following areas:

[0194] - a large part of the front plate 105,

[0195] - a large part of the flat part of the wall 101 which extends the plate 105 and forms part of the front side of the frame,

[0196] - a large part of the rounded edge 101r of the wall 101, and optionally

[0197] - A flat portion of the wall 101 which forms part of the rear side of the frame.

[0198] The term "majority" means, for example, at least 90% of the area involved.

[0199] The extension 224 of the touch module then passes under the cover 110 and penetrates the chassis to allow the I2C bus connector 226 to be attached to the PCB 11 .

[0200] Preferably, the touch area 220a of the module 22 covers only the front plate 105 and the flat portion of the wall 101 which extends the plate 105 and forms part of the front side of the frame, while its non-touch area 220b covers the rounded edge 101r and the flat portion of the wall 101 which forms part of the back side of the frame.

[0201] The touch screen TS thus enables the security element to:

[0202] - Display information on the front side of the rack and collect tactile information,

[0203] - Displaying information on the rounded edge 101r without the risk of collecting unintentional tactile information due to manipulation of the chassis by the user.

[0204] The device HW3, while meeting the stringent security requirements required for its function as a hardware wallet, offers significant ergonomic advantages usually reserved for medium-security devices whose screens are not controlled by a secure element running on Android or equivalent, and have the additional possibility of displaying specific information on the edge of the frame.

[0205] Exemplary embodiment of a hardware wallet including a magnetic stacking device

[0206] As mentioned above, some crypto asset holders may use multiple hardware wallets to manage crypto resource accounts of different types or values, such as low currency value accounts, high currency value accounts, non-fungible tokens or smart contract accounts, etc.

[0207] A third improvement (which may or may not be combined with the previous improvements) provides a hardware wallet that can be magnetically stacked with similar hardware wallets.

[0208] More specifically, a hardware wallet is provided that includes at least four magnets arranged to magnetically cooperate with four magnets from at least one similar hardware wallet so as to ensure magnetic stacking of the hardware wallet with similar hardware wallets regardless of which hardware wallet is on top of another.

[0209] In one embodiment, the magnets are arranged asymmetrically to form a magnetic keying for stacking, where an edge of a frame of a hardware wallet is aligned with the same edge of a similar hardware wallet, and where each magnet faces a corresponding magnet of a similar device.

[0210] Fig.19 , Fig. 20 , Fig.21 A device HW3 according to this embodiment is shown. Fig.19 is a cross-sectional view of device HW3, Fig. 20is a top view, and Fig.21 is an exploded perspective view. Fig.19 In FIG. 1 , the front side FS of the frame 10 is at the top. Fig. 20 and Fig.21 In the figure, the rack is viewed from its rear side RS.

[0211] The frame 10 is provided with four magnets M1, M2, M3 and M4, which preferably have the same magnetic orientation, for example with the north pole facing the front of the frame. The magnets M1 and M2 are arranged in slots 103-1, 103-2 formed in the lateral side walls 103 of the frame, which slots extend substantially through the entire thickness of the frame. The magnets M1 and M2 thus generate a magnetic field on both sides of the frame.

[0212] like Fig.19 As shown, the magnets M3 and M4 each include two stacked magnets M3a-M3b and M4a-M4b. The magnets M3a and M4a are arranged in the gaps 105-3 and 105-4 provided in the front plate 105 of the frame ( Fig. 20 , Fig.21 ), while the magnets M3b, M4b are attached to the cover 110 in a recess provided in the cover for this purpose, opposite to the gaps 105-3, 105-4. Fig.19 As shown, the magnets M3a and M3b, M4a and M4b extend through less than half of the thickness of the frame, and the space between them advantageously allows the printed circuit board 11 to pass through.

[0213] In the following, magnets M3 and M4 will be considered as integral, similar to magnets M1 and M2, since their structure in two superimposed magnets does not modify the reasoning given below.

[0214] The arrangement of the magnets M1, M2, M3, M4 is here selected so that during magnetic stacking of the device HW3 with a similar device HW3-1 a magnetic adaptation is formed, such as Fig.24 . The intended stacking arrangement is one in which an edge of the frame of device HW3 is aligned with the same edge of device HW3-1 and in which each magnet of device HW3 faces a corresponding magnet of a similar device HW3-1. This arrangement should preferably be unique so that there is only one magnetic stacking position in which the devices HW3, HW3-1 have their respective edges aligned. In other words, when the stacking arrangement is not the same (for example, if the devices are arranged head to tail), the devices are not magnetically attached. The arrangement of the magnets therefore prevents the devices from being mispositioned so that the devices do not magnetically attract each other in this case.

[0215] For this purpose, and with reference to Fig. 20 and Fig. 22, defining a longitudinal center axis L-L' of the frame, which is located in the middle between the longitudinal lateral edges 101, 102 of the frame, and defining a transverse center axis T-T' of the frame, which is located in the middle between the transverse lateral edges 103 and 104 of the frame. The axes L-L' and T-T' define four quadrants Q1, Q2, Q3, Q4, and each magnet is arranged in one of these quadrants. The magnets M1, M2, M3, M4 are arranged asymmetrically with respect to the longitudinal center axis L-L' or with respect to the transverse center axis T-T'. A combination of these two asymmetries can also be used for all or part of the magnets. To more precisely formulate this asymmetry, each magnet M1, M2, M3, M4 is defined as having a center point cm1, cm2, cm3, cm4 (cmi), a longitudinal dimension lm1, lm2, lm3, lm4 (lmi), and a transverse dimension tm1, tm2, tm3, tm4 (tmi), such as Fig.23 shown.

[0216] In addition, define the following axes and distances, such as Fig. 20 and Fig. 22 As shown in:

[0217] - L1-L1' is the longitudinal axis passing through the centre point of the magnet M1 and parallel to the longitudinal centre axis LL',

[0218] -t1 is the transverse distance between the axes L1-L1' and L-L',

[0219] - L2-L2' is the longitudinal axis passing through the centre point of the magnet M2 and parallel to the longitudinal centre axis LL',

[0220] -t2 is the transverse distance between the axes L2-L2' and L-L',

[0221] - L3-L3' is the longitudinal axis passing through the centre point of the magnet M3 and parallel to the longitudinal centre axis LL',

[0222] - t3 is the transverse distance between the axes L3-L3' and LL',

[0223] - L4-L4' is the longitudinal axis passing through the centre point of the magnet M4 and parallel to the longitudinal centre axis LL',

[0224] - t4 is the transverse distance between the axes L4-L4' and LL',

[0225] - T1-T1' is a transverse axis passing through the centre point of the magnet M1 and parallel to the transverse centre axis TT',

[0226] -l1 is the longitudinal distance between the axes T1-T1' and T-T',

[0227] - T2-T2' is a transverse axis passing through the centre point of the magnet M2 and parallel to the transverse centre axis TT',

[0228] -l2 is the longitudinal distance between the axes T2-T2' and T-T',

[0229] - T3-T3' is a transverse axis passing through the centre point of the magnet M3 and parallel to the transverse centre axis TT',

[0230] -l3 is the longitudinal distance between the axes T3-T3' and T-T',

[0231] - T4-T4' is a transverse axis passing through the center point of magnet M4 and parallel to the transverse center axis TT', and

[0232] -l4 is the longitudinal distance between the axes T4-T4' and T-T'.

[0233] In one embodiment, it can be provided that the at least two magnets have different lateral distances t1 to t4 or longitudinal distances l1 to l4.

[0234] In one embodiment, one of the following design rules or a combination of two or more of these rules is implemented:

[0235] - the lateral distances t1 to t4 are all different from one another,

[0236] - the longitudinal distances l1 to l4 are all different from one another,

[0237] - Some of the transverse distances t1 to t4 are different, and some of the longitudinal distances l1 to l4 are different.

[0238] In another even stricter asymmetric implementation, one of the following rules is added to one or a combination of the above rules:

[0239] the difference between each transverse distance t1, t2, t3, t4 and each of the other transverse distances is at least equal to the sum of half the transverse dimensions tm1, tm2, tm3, tm4 of the corresponding magnet, or

[0240] The difference between each longitudinal distance l1, l2, l3, l4 and each of the other longitudinal distances is at least equal to the sum of half of the longitudinal dimensions lm1, lm2, lm3, lm4 of the corresponding magnet.

[0241] Or, by combining the two rules:

[0242] - The difference between certain lateral distances T1, T2, T3, T4 is at least equal to the sum of half of the lateral dimensions tm1, tm2, tm3, tm4 of the corresponding magnets, and the difference between certain longitudinal distances L1, L2, L3, L4 is at least equal to the sum of half of the longitudinal dimensions lm1, lm2, lm3, lm4 of the corresponding magnets.

[0243] exist Fig. 20 In the embodiment shown, the center cm2 of the magnet M2 is arranged on the transverse axis T1-T1' of the magnet M1, and the center cm4 of the magnet M4 (M4a, M4b) is arranged on the transverse axis T3-T3' of the magnet M3 (M3a, M3b). The longitudinal distances l1, l2 are equal, and the longitudinal distances l3, l4 are also equal, but the longitudinal distances l1, l2 are different from the longitudinal distances l3, l4. In addition, the transverse distances t1, t2, t3, t4 are all different, and the minimum deviation between the transverse distances (here the difference between the distances t1 and t3 and the difference between the distances t2 and t4) is approximately equal to the sum of half the transverse dimensions of the corresponding magnets (i.e., M1, M3 on the one hand and M2, M4 on the other hand). The term "approximately" is understood here to be within a few tenths of a millimeter.

[0244] It will be clear to those skilled in the art that the improvement just described may have various other variations and embodiments. In particular, the magnets M1 and M2 themselves may comprise two superimposed magnets, such as Fig.25 As shown, Fig.25 Variant HW4 of the device is shown with a magnet M1 formed by a pair of magnets M1a, M1b. On the contrary, the magnets M3 and M4 can be integral and extend through the entire thickness of the frame, such as Fig.26 As shown, Fig.26 A variant HW5 of a device is shown which is provided with an integral magnet M3 identical to magnet M1. Similarly, the attachment of the magnets to the frame may be accomplished in a variety of ways other than those described. In particular, if the printed circuit board is sufficiently strong to withstand the separation forces exerted on each magnet when separating two magnetically stacked devices, the magnets or some of them may be attached directly to the printed circuit board. Finally, although this improvement does not require this, in some embodiments, the polarity of the magnets may not all be the same. It will also be clear to those skilled in the art that the improvement just described may be applied to any type of portable electronic device to be stacked with similar devices.

[0245] Exemplary embodiments of portable electronic devices with interactive stacking capabilities

[0246] Examples of magnetically stackable devices according to the third improvement have been described above. According to a fourth improvement, stacking devices implement an interactive stack management method that allows them to be used as they appear in a stack despite the fact that their front screens are no longer accessible.

[0247] For example, Fig. 27 As shown, the user may have three hardware wallets HW3, HW3-1, HW3-2 and stack them magnetically. The user may want to access their content or check their status (battery level, crypto asset wallet, value of private key, etc.) without undoing the stack. The user may also want to use the device to complete transactions on the blockchain BCN or decentralized exchange DEX by linking one of the devices to the host device HDV, or to update or download applications via the module HSM.

[0248] According to this embodiment, when the user requests, the device at the top of the stack makes its display available to other devices. The term "making available" means that the user can use the screen of the device at the top of the stack to view or use the device inside the stack.

[0249] To this end, the devices communicate with each other via a wireless data link. In the case of the device HW3 as described above, this link is for example a multipoint Bluetooth link, after pairing the devices and preferably after pairing the device with the host device HDV.

[0250] The organization of data exchange between stacked devices can be done according to a mesh, chain, or hierarchical communication strategy. In a mesh communication strategy, each device can communicate with any other device. Fig. 27 In the example shown, this strategy involves wireless links SLNK1, SLNK2, SLNK3 between the devices. In a chained communication strategy, each device can communicate with the device immediately below or above it in the stack. Fig. 27 In the example shown, this strategy involves wireless data links SLNK1 and SLNK2. In a hierarchical communication strategy, a device at the top of a stack communicates with the device below it, and two devices within a stack do not communicate with each other. Fig. 27 In the example only links SLNK1 and SLNK3 are used.

[0251] Since this improvement is applicable to any type of electronic portable device including wireless communication means (particularly Wi-Fi), the choice of communication strategy may vary depending on the type of wireless data link used. A hierarchical communication strategy may be preferred, for example, in the case of a Bluetooth link. In the case of a Wi-Fi link, a mesh communication strategy may be preferred.

[0252] In one embodiment, each device in the stack is assigned one of the following operating modes according to the improved interactive stacking method:

[0253] - Mode SM0, or "Stacking Mode Disable",

[0254] - Mode SM1, or "override" mode,

[0255] - Mode SM2, or "top" mode,

[0256] - Mode SM3, or "middle" mode.

[0257] In modes SM1, SM2, and SM3, stacked modes are enabled, and each mode switches the position of the devices in the stack and corresponds to designated displays "F" and "E":

[0258] model Stacking Mode Location monitor SM0 Disable isolation F0, E0 SM1 Enable Bottom of the stack F1, E1 SM2 Enable Top of the stack F2, E2 SM3 Enable Between two devices F3, E3

[0259] In order to make the best use of the display possibilities offered by the above-mentioned touch screen TS, each mode is assigned an "F" display on the front side ("front display") and an "E" display on the edge of the device ("edge" display). In the above-mentioned embodiment, the "E" display corresponds to the display of information on the non-touch area of ​​the touch screen TS above the rounded edge 101r of the frame. The "F" display can correspond to one or more different menus, allowing the management of the stack or the individual management of one of the devices that make up the stack.

[0260] The operating mode SM0 corresponds to the normal operating mode of the device HW3. The device HW3 in mode SM1 or SM3 is covered by another device and will therefore not be available without the method described herein. The device in mode SM2 is located at the top of the stack and can be used normally because its screen is accessible to the user, but it can also make its screen available to other devices at the request of the user. Depending on the interactive management needs of the stack, it may not be necessary to provide the operating mode SM3. In particular, when the device in the "top" mode addresses each of them, it may not be necessary to know which devices are at the bottom or in the middle of the stack.

[0261] Display F0 is the usual display presented to the user when the device is used with stacking mode disabled. Display F1 ("overlay") or F3 ("middle") can be arbitrary, since the user cannot see the screen of the device. The display can be blank or display an image or information, such as "this device is in stacking mode". But it can also display instructions, such as "disable stacking mode", which may be useful if the user interrupts the stacking without first notifying the device at the top of the stack that stacking mode should be disabled (the device will send this information to the other devices).

[0262] Display F2 may include a preview of a menu through which the user selects the device they wish to control via the screen. Fig.28 An example of such a menu is shown in . The user is prompted to select between "this device" or one of the other two devices HW3-1, HW3-2. If the user selects "this device", display F2 switches to display F0' which is similar to display F0, with a "back" button added to allow the user to make a new selection. If the user selects "HW3-1" or "HW3-2", display F2 switches to display F0", which is similar to display F0, but with an additional indication that the device being used is not "this device" but is the device that has been selected. A back button is also provided to allow the user to make a new selection.

[0263] Thus, using a device located inside the stack through the screen of the device at the top of the stack can be similar to using the device when the stack mode is disabled, where the display F0' or F0" includes the same menu as the display F0. For example, the user can choose to connect the device to the host device HDV using the data link LNK1, LNK2 or LNK3 to conduct a transaction, such as Fig. 27 shown.

[0264] The edge displays E0 to E4 are optional, but may provide additional comfort to the user, since the edge displays are visible despite the stacking of the devices. These displays may be the same or different. For example, they may display the name of the device or its serial number. When a device in mode SM1 or SM3 is selected by a device in mode SM2, the display of the device name or serial number may flash or scroll, rather than remain static.

[0265] Fig.29 Depicted is the SM2 placed in the "top" mode ( Fig. 27) is performed by device HW3 thereafter. At step S10, device HW3 interrogates all devices in the stack to identify them. It should be noted that, for security reasons, the specific implementation of these various data links preferably requires a previous device configuration step during which each device is informed of the devices it can stack with. Therefore, no device is allowed to appear in the stack that has not been previously declared by the user. Similarly, it may be desirable for devices HW3, HW3-1, HW3-2 to securely authenticate each other using their cryptographic means before agreeing to communicate with each other.

[0266] At step S11, the device HW3 presents a list of devices to the user and, for example, Fig.28 The above-described manner shown in requires them to make a selection. At step S12, device HW3 establishes or re-establishes communication with the device specified by the user. At step S13, device HW3 receives the information to be displayed from the selected device and displays the information on its touch screen. At step S14, device HW3 detects the user's action on its touch screen and sends it to the selected device at step S15. As long as the user is using the selected device, this process can continue indefinitely until step S16, where the user returns to the selection menu ( Fig.28 ) to select another device or request to put all devices to sleep.

[0267] The specific implementation of this interactive stack management process assumes that each device can activate a stack mode and knows its position in the stack to place itself in the corresponding mode SM1 or SM2, or optionally in mode SM3. To this end, the stack management method can be implemented automatically or manually.

[0268] As part of the automatic implementation of the method, each device HW3, HW3-1, HW3-2 is equipped with a sensor 108a, 108b, such as Fig.30 These sensors allow devices to detect the presence of another device below or above them. If the devices are equipped with magnets, the sensors 108a, 108b may be Hall Effect sensors capable of detecting the presence of a magnet below or above each device. The sensors 108a, 108b may be as shown. Figure 5 As shown it is connected directly to the secure element SE3, or to the microcontroller MCU3. A variety of other types of sensors may be used, such as optical, acoustic, piezoelectric, electromagnetic, thermal, capacitive sensors, etc., especially if the stacked device does not have a magnet.

[0269] In one embodiment, the sensor allows positive identification that an object detected above or below a device HW3, HW3-1, HW3-2 is a similar device suitable for placement in stacking mode. This uncertainty can be eliminated by the device in "top" mode based on the reply received to its identification request. Similarly, a device that detects an object placed on it and does not receive any identification request will understand that the object is not a compatible device.

[0270] Fig.31 is a state diagram showing an example of an automatic specific implementation of the interactive stack management method. In this example, four operating modes SM0, SM1, SM2, and SM3 are managed. Device HW3 is in mode SM0 by default. At step S22, the device detects the presence of the device on it and switches to mode SM1, where the device waits to be queried by the device in the "top" mode. As an alternative, the device detects the presence of the device below it at step S23 and switches to the "top" mode to query and identify other devices in the stack. If the device is in mode SM2 and detects that the device has been placed on top of it at step S24, it switches to mode SM3. Once in mode SM3, if the device on it is no longer detected at step S25, the device reverts to mode SM2. Finally, no matter which of modes SM1, SM2, and SM3 it is in, if the device detects that there is no longer a device above or below it at step S20, it automatically returns to mode SM0.

[0271] In a manual implementation of the method, the user accesses a menu for manually activating stacking mode, an example of which is shown in FIG. Fig.32 The user first activates the stacking mode and then chooses between the "overlay" mode SM1 and the "top" mode SM2. In this example, mode SM3 is not supported.

[0272] Fig.33 is a state diagram showing an example of a manual implementation of the interactive stack management method. The device HW3 is in mode SM0 by default. At step S30, the user activates the stacking mode. At step S31, the user selects mode SM1, or at step S32, mode SM2. At any time, the user can return to step S31 or S32 to change the operating mode of the device and change its position in the stack. Similarly, at step S33, the user can deactivate the stacking mode at any time.

[0273] When the method is applied to a hardware wallet of the above type, the modes SM0, SM1, SM2 and optionally SM3 are preferably managed by the operating system OS3 of the secure element SE3. To this end, a module for automatic stack management ASM is provided in the operating system, such as Figure 6 As shown. Alternatively, the operating system OS3 provides a module MSM for manual stack management. In some embodiments, the two modules can coexist, providing the user with a choice between automatic management or manual management. Each of these modules allows the device to be placed in different operating modes and to operate as required by these modes. When the operating mode SM3 is not supported, it is included in the mode SM1, which supports the situation where the device is at the bottom of the stack and the situation where the device is in the middle of the stack.

[0274] It will be clear to a person skilled in the art that the method according to the present improvement is applicable to any type of portable electronic device comprising wireless communication means (particularly Wi-Fi), and its scope is not limited to hardware wallets for cold storage of private keys. Similarly, the method does not exclusively relate to the use of magnets to stack devices, as stacking can be provided without the devices being magnetically held against each other. Furthermore, the method is applicable to devices that do not have a display (display E) at the edge of the frame, but only a display (display F) on the front side.

[0275] In some embodiments, the interactive stack management method may also involve the host device HDV. In this case, the companion software menu has a "Stack Management" option that allows the user to select the hardware wallet ( Fig. 27 ). The hardware wallet at the top of the stack is then notified by the companion software that it should make its screen available to the selected hardware wallet via the host device.

[0276] Exemplary embodiments of an adaptive Bluetooth antenna with two radiating axes, particularly for stackable devices

[0277] In the above, a method for providing a Bluetooth antenna BTA ( Figure 5 ) and a hardware wallet with a touch screen TS. A hardware wallet made of an aluminum frame is also described, which includes a front panel ( Fig. 9 Finally, a hardware wallet is described that can be magnetically stacked with similar hardware wallets ( Fig. 27 ) and a method for interactively managing a stack of hardware wallets by wireless communication between the stacked hardware wallets, in particular via a Bluetooth link.

[0278] Tests conducted by the applicant on commercially available Bluetooth antennas in the form of integrated components have shown that due to the metal mass of the frame 10, in particular the conductive wall 105 ( Fig. 9), this type of assembly is not suitable for obtaining good quality Bluetooth communications. In normal use (device HW3 is outdoors), this metal mass causes a strong attenuation of the gain of these conventional antennas by acting as a barrier (in the sense of shielding) with respect to the electromagnetic fields emitted by these conventional antennas. The gain is so low that it does not allow a stable Bluetooth connection to be established.

[0279] The applicant also conducted tests using an IFA antenna ("inverted F antenna"), which is an antenna commonly used in mobile phones, where the antenna is placed close to the edge of the frame. In normal use (device HW3 is not stacked and outdoors) a relatively small gain is obtained, but Bluetooth communication is still allowed. On the other hand, when two devices HW3 and HW3-1 are stacked (e.g., Fig.30 ), the device at the top of the stack will see its antenna gain weakened, which may result in unstable Bluetooth communications.

[0280] It may therefore be desirable to provide an advanced RF antenna structure that may be used, but not exclusively used, in a portable electronic device that includes a conductive chassis and that provides relatively stable performance under two conditions of use, including use outdoors on the one hand and use in the presence of conductive surfaces on the other hand, such as when the device is stacked with similar devices.

[0281] According to a fifth improvement, a radio frequency antenna is provided, which includes a combination of a closed slot antenna made in a side wall of a frame, the closed slot antenna having a radiation axis substantially perpendicular to the wall, and an open slot parasitic antenna having a radiation axis perpendicular to the radiation axis of the closed slot antenna. Taking into account the above two operating conditions, a radio frequency field simulation computer tool is used to configure (i.e., adjust) the two antennas. The result is that the performance of the antenna under these two operating conditions is more or less the same. A detailed non-limiting example of the construction of such an antenna will be described below.

[0282] Exemplary embodiments of closed slot antennas

[0283] exist Fig.34 The main components of the closed slot antenna embodiment are shown in the exploded view of FIG. The assembled antenna structure is as follows Fig.38 , Fig.39 , Fig.42 , Fig.43 As shown. Fig.34 , Fig.39 , Fig.42 , Fig.43 In FIG. 1 , the frame 10 is seen from its rear side RS, with the plate 105 located at the bottom. Fig.38 In the cross-sectional view of FIG. , plate 105 is at the top. Therefore, compared with the other figures, Fig.38The position or orientation of the components in is reversed.

[0284] refer to Fig.34 The closed slot antenna includes a longitudinal port 40 made in one wall of the frame (in this case, the longitudinal side wall 102). The antenna also includes an RF signal injector 50 to apply a ground voltage and an RF signal RFS to the port 40, the signal being provided by a circuit board ( Fig.12 ) on the circuit BTM( Figure 5 )supply.

[0285] from Fig.35 The longitudinal port 40, seen from the front, comprises two longitudinal surfaces 41, 42 facing each other, connected by two lateral surfaces 44, 45, which are here substantially of rounded shape. It has a length Ls (also the length of the longitudinal surfaces 41, 42) and a height Hs. The wall 102 also has a non-transverse recess 45, which is not considered to be included in the port 40.

[0286] The injector 50 is made of a flexible printed circuit board and has two electrodes 51, 52. The electrode 51 is placed on the surface 41 of the port 40, and the electrode 52 is placed on the surface 42 of the port. The injector 50 also includes a connecting portion 53 extending between the electrodes 51, 52 and an extension 54 extending the electrode 51.

[0287] Fig.36 and Fig.37 The injector 50 is shown in a top view and a bottom view, respectively. The top view shows the outer surface of the injector in contact with the surfaces 41, 42. Before the folding that occurs when the injector is inserted into the port 40, the injector is a flat portion, as seen in these figures. The injector includes various conductors 500, some of which are on the surface and some of which are buried. It also includes contact pads Pc1, Pc2, Pc3, Pc4, Pc5, Pc6 for soldering components, in this case, the soldering components are capacitors C1, C2, C3 participating in the closed slot antenna configuration. Finally, the injector 50 includes a connector 540 arranged on the extension 54, allowing it to be connected to a printed circuit board to receive a ground voltage and a radio signal RFS.

[0288] When the injector 50 is inserted into the port 40, a compression element 55 or spacer is inserted between the electrodes 51, 52, such as in Fig.38 The compression element 55 is made of a soft material such as silicone rubber and presses the electrodes 51, 52 against the surfaces 41, 42. It should be noted that the electrodes 51, 52 here only cover the edges of the surfaces 41, 42, and the outer part of the port 40 is blocked by the non-conductive plug 47 ( Fig.38). The electrodes 51, 52 may be coated with a gold layer 520 to ensure good electrical contact with the surfaces 41, 42. These surfaces may also be made by milling to provide good conductivity, especially if the aluminum frame has been previously anodized.

[0289] Advantageously, electrodes 51, 52 here have a large contact surface with surfaces 41, 42, the length of which is at least equal to one quarter of the length Ls of surfaces 41, 42. They are preferably inserted in the middle of port 40 so that their edges are at the same distance from walls 44 and 45 of the port.

[0290] Fig.40 is a circuit diagram of an injector. The connector 540 has a plurality of ground contacts 541 connected to an electrode 51 forming a ground layer (GND). It is also characterized by a contact 542 for receiving a radio frequency signal RFS. The contact 542 is connected to a pad Pc3' via a conductor 500. The capacitor C3 has a first terminal connected to the pad Pc3' and a second terminal connected to the pad Pc3, which is in turn connected to the electrode 51. The capacitor C1 has a first terminal connected to the pad Pc1' and a second terminal connected to the pad Pc1. The capacitor C2 has a first terminal connected to the pad Pc2' and a second terminal connected to the pad Pc2, which is in turn connected to the electrode 51. The conductor 500 connects the pad Pc1 to the pad Pc3', and connects the pad Pc1' to the pad Pc2' and to the electrode 520. As Fig.41 As shown, the surface 42 receives the radio frequency signal RFS via the capacitor C3, the second terminal of which is connected to the surface 41 via the capacitor C3. The surface 41 is at ground voltage and is connected to the surface 42 via the capacitor C2.

[0291] The configuration just described is merely exemplary in nature, and those skilled in the art may provide various other arrangements and selections of components that participate in the antenna configuration.

[0292] Exemplary embodiments of open slot parasitic antennas

[0293] exist Fig.34 The main components of an example of an open slot parasitic antenna are shown in the exploded view of FIG. The structure of the assembled antenna is shown in FIG. Fig.42 , Fig.43 The open slot parasitic antenna has an arm 70 made of a conductive metal (e.g., stainless steel or nickel-plated mild steel). The arm 70 has a rectangular cross-section with a small thickness to make it flexible, and has a length Lb. It is parallel to the plane ( Fig.38 ) and in a plane close to the plane, extending along the wall 102 of the frame, and being spaced a distance Db ( Fig.38 ), that is, the distance Db from the inner edges of the surfaces 41 and 42 of the port 40.

[0294] The arm 70 has a free end 701 and a captive end 702. The end 702 is wider than the rest of the arm and extends towards the wall 102 where it has a protruding contact portion 71, obtained for example by stamping, which rests on a contact surface 107 formed in the wall 102 ( Fig.43 ).

[0295] As an extension of the end 702, the arm 70 also has a base 703 with a hole 704. A screw 705 passing through the hole 704 is screwed into a screw provided in the wall 102 ( Fig.34 , Fig.43 ) formed in the receiving surface 108 of the threaded hole 106 ( Fig.34 )middle.

[0296] The arm 70 is attached to the wall 102 while exerting an elastic flexure thereon between its base 703, which is screwed to the receiving surface 108, and the protruding contact 71, which rests on the contact surface 107. This flexure exerts sufficient pressure on the contact 71 to ensure that the electrical contact between the arm 70 and the surface 107 does not change over time.

[0297] The electrical contact of arm 70 with wall 102 (in this case contact surface 107) is preferably close to surface 42 receiving the RF signal so that the parasitic antenna is indirectly fed by the RF signal applied to the closed slot antenna. In particular, this point is preferably close to the end of surface 42. Fig.42 As can be seen in FIG. 4 , the protruding contact portion 71 is here close to the lateral surface 44 of the port.

[0298] refer to Fig.34 or Fig.43 The open slot parasitic antenna also has a portion 80 with a guide wall for the arm 70 to ensure parallelism with the wall 102. Fig.44 Also shown is the guide portion 80. The free end 701 of the arm 70 is shown in two positions: a relaxed position P1 (701) before installation in the frame; and a position P2 (701) subjected to the above-mentioned elastic bending, in which the protruding contact portion 71 resting on the surface 107 forces the arm to a horizontal position.

[0299] Fig.45is a schematic diagram showing an antenna resulting from a combination of a closed slot antenna and an open slot parasitic antenna. The closed slot antenna comprises surfaces 41 and 42 of port 40 connected by walls 43, 44. The open slot parasitic antenna comprises an arm 70 connected to wall 102 by a protruding contact 71 provided on a tethered end 702. The closed slot antenna has a Y radiation axis that is substantially perpendicular to the side wall 102 of the chassis, while the open slot parasitic antenna has an X radiation axis that is substantially perpendicular to the Y axis and therefore parallel to the side wall 102 and perpendicular to the plane of the chassis 10.

[0300] Example of tuning and optimizing the resulting antenna

[0301] The closed slot antenna and the open slot parasitic antenna together form the resulting antenna, the design and tuning parameters of which can be determined by computer simulation. To this end, the frequency band in which the antenna is to be used is first determined. For example, this can be the Bluetooth band or the 2.45 GHz Wi-Fi band, where the channel width can vary depending on the chosen technology.

[0302] In an embodiment providing the results to be described below, the simulation is intended to optimize an antenna in a Bluetooth communication environment, i.e., an antenna in a target frequency band TFB between a frequency Fmin of 2.4 GHz and a frequency Fmax of 2.483 GHz, to obtain at least one of the following results:

[0303] (1) When the rack 10 of the device HW3 is outdoors, the resulting antenna gain in the target frequency band is greater than -5dB, and when the rear side of the rack faces a conductive surface (particularly the plate 105 of the rack of similar devices HW3-1, HW3-2), the resulting antenna gain in the target frequency band remains greater than -5dB.

[0304] (2) When the rack 10 is outdoors, the open slot parasitic antenna has a tuning frequency within the target frequency band,

[0305] as well as

[0306] (3) When the rear side of the housing 10 faces a metal surface, and in particular, the front panel 105 of a housing of similar equipment, the closed slot antenna has a tuning frequency within the target frequency band.

[0307] In other words, depending on the operating conditions, the radiation from the closed slot antenna will dominate the radiation from the open slot parasitic antenna, or vice versa.

[0308] Of the numerous parameters used to tune an antenna to achieve a desired result, the most important include:

[0309] - the length Ls of the longitudinal port 40, i.e. the length of the closed slot antenna,

[0310] - the height Hs of the longitudinal port 40, i.e. the aperture of the closed slot antenna,

[0311] - the length Lb of the arm 70, which is the length of the open slot parasitic antenna,

[0312] - The previously described distance Db between the arm 70 and the port 40, ie the aperture of the parasitic open slot antenna.

[0313] As a starting point for the simulations, the theoretical length of the longitudinal port 40 was chosen to be equal to a quarter of the wavelength of a frequency of 2.45 GHz, i.e. 30.6 mm. The tests and simulations set up to achieve the above-mentioned purpose lead to significantly different values ​​accurate to within a few millimeters or tenths of a millimeter, due to the presence of the open slot parasitic antenna. Thus, at the end of the simulations and tests, as an example, the following values ​​were obtained:

[0314] - Length Ls of the longitudinal port 40: 30 mm;

[0315] - Height Hs of the longitudinal port 40: 2.1 mm;

[0316] - length Lb of arm 70: 22 mm;

[0317] -Distance Db: 1.6mm.

[0318] It will be clear to a person skilled in the art that these values ​​may vary depending on other parameters of the antenna, such as the electronic components of the injector 50 (here capacitors C1 to C3), the shape of the housing and the location of the port on one of its walls, the amount of metal that constitutes the housing, etc.

[0319] Fig.46 and Fig.47 A graph showing the resulting antenna reflection loss or return loss obtained using the dimensions provided above is shown. Fig.46 A reflection loss curve RL1 is shown when the device HW3 is located outdoors. Fig.47 shows when device HW3 is stacked on top of a similar device HW3-1 (e.g. Fig.48 Each curve shows two low values ​​of the reflection loss at the frequencies corresponding to the tuning frequency FT1 of the closed slot antenna and the tuning frequency FT2 of the open slot parasitic antenna, respectively. In particular:

[0320] -FT1a( Fig.46 ) is when the device is outdoors or when the device is in another similar device (e.g. Fig.48 The two cases are considered similar because the conductive plate 105 forms a barrier that makes the antenna insensitive to what is above it;

[0321] -FT1b( Fig.47 ) is when the device is placed on a metal surface or on another similar device (e.g. Fig.48 The tuning frequency of the closed slot antenna when the device HW3 is on;

[0322] -FT2a( Fig.46 ) is when the device is outdoors or when the device is in another similar device (e.g. Fig.48 The tuning frequency of the open slot parasitic antenna when it is below the device HW3-1 in FIG. In both cases, the conductive plate 105 forms a barrier that blocks the radiation emitted by the parasitic antenna upward along the X-axis, and the presence of the metal mass above the device does not change its characteristics;

[0323] -FT2b( Fig.47 ) is when the device is placed on a metal surface or on another similar device (e.g. Fig.48 In this case, the conductive plate 105 blocks the radiation emitted downward along the X-axis by the parasitic antenna.

[0324] With the tuning frequencies of the closed slot antenna and the open slot parasitic antenna selected for lowest reflection loss, the following results are obtained:

[0325] Fig.46 (outdoor):

[0326] -FT1a=2.32GHz, i.e. FT1a <Fmin

[0327] -FT2a=2.42GHz, i.e. Fmin <FT2a<Fmax

[0328] Fig.47 (Place on metal surface or other equipment):

[0329] -FT1b=2.475GHz, i.e. Fmin <FT1b<Fmax

[0330] -FT2b=3.15GHz, that is, Fmax< <FT2b

[0331] Where (for the record):

[0332] -Fmin=2.4GHz

[0333] -Fmax=2.483GHz

[0334] exist Fig.46In this case, the tuning frequency FT1a of the closed slot antenna is "out of band", while the tuning frequency FT2a of the open slot parasitic antenna is in the target frequency band. The radiation from the parasitic open slot antenna is dominant over the radiation from the closed slot antenna.

[0335] exist Fig.47 In the case of , the tuning frequency FT1b of the closed slot antenna is in the target frequency band, while the tuning frequency FT2b of the open slot parasitic antenna is out of band. Fig.48 As can be seen in Figure 1, the parasitic open slot antenna sees two electromagnetic barriers above and below it along its X-radiation axis. The upper barrier is formed by the wall 105 of the rack in which it is located, and the lower barrier is formed by the wall 105 of the equipment HW3-1. Therefore, in this case, the radiation from the closed slot antenna dominates the radiation from the parasitic open slot antenna.

[0336] at last, Fig.49A and Fig.49B shows the resulting antenna gains CG1, CG2 when the device HW3 is in the open air, and Fig.50A , Fig.50B The resulting antenna gains CG3, CG4 are shown when the device HW3 is placed on a metal surface or similar device HW3-1. In particular, Fig.49A , Fig.50A The resulting antenna gains CG1 , CG3 are shown in the YZ plane, which is the plane of the rack or the horizontal plane when the rack is lying flat. Fig.49B , Fig.50B The gains CG2, CG4 of the resulting antenna in the vertical plane X-YZ are shown, the vertical plane X-YZ being a plane perpendicular to the rack or a vertical plane when the rack is laid flat. In the first case, a peak gain of -1.5 dB is obtained at a horizontal angle of 225 degrees and a vertical angle of 105 degrees. In the second case, a peak gain of -3.4 dB is obtained at a horizontal angle of 90 degrees and a vertical angle of 120 degrees.

[0337] therefore:

[0338] (1) the resulting antenna gain in the target frequency band is greater than -5 dB when the equipment rack is outdoors, and the resulting antenna gain in the target frequency band remains greater than -5 dB when the rear side of the rack of equipment HW3 faces a conductive surface (including plate 105 of racks like equipment HW3-1, HW3-2),

[0339] (2) when the rack 10 is outdoors, the open slot parasitic antenna has a tuning frequency within the target frequency band, while the closed slot antenna has a tuning frequency outside the target frequency band, and

[0340] (3) When the rear side of the rack faces a metal surface, and in particular, the front plate 105 of a rack of similar equipment, the closed slot antenna has a tuning frequency within the target frequency band, while the open slot parasitic antenna has a tuning frequency outside the target frequency band.

[0341] In other words, when the resulting antenna is located between two conductive plates, it radiates primarily from the sides of the rack, whereas when the rack is outdoors, the resulting antenna radiates primarily from the underside of the rack having the plastic cover.

[0342] Those skilled in the art will appreciate that the above improvements are variable and are not limited to the application environment for which they are designed. Generally speaking, the combination of the above closed slot antenna and the open slot parasitic antenna is not related to the above frame structure 10, and its application is not limited to hardware wallets. This combination can be used in a variety of applications and portable electronic devices, including but not limited to use conditions where the metal environment of the antenna can vary widely.

[0343] It will also be clear to those skilled in the art that, although described above in conjunction with a hardware wallet for storing private keys, the second, third, fourth and fifth improvements are independent of one another and may be the subject of separate specific implementations and various applications in addition to being applied to hardware wallets.

Claims

1. An electronic device (HW3), comprising: - a frame (10) of conductive material, said frame comprising a front side (FS), a rear side (RS), side walls (102) and a conductive plate (105) located on the front side (FS) of said frame, - a radio frequency antenna (40, 50, 70, 102) designed to transmit or receive data in a specified frequency band, and - a wireless communication circuit (MCU3), the wireless communication circuit being configured to provide a radio frequency signal (RFS) to the radio frequency antenna, Features: - the radio frequency antenna comprises a combination of a closed slot antenna (40, 50) and an open slot parasitic antenna (70, 102), the closed slot antenna being fabricated in the side wall (102) of the housing and having a radiation axis (Y) substantially perpendicular to the side wall (102) of the housing, and the open slot parasitic antenna having a radiation axis (X) substantially perpendicular to the radiation axis (Y) of the closed slot antenna, - the conductive plate (105) forms a first shield for the radiation emitted by the open slot parasitic antenna, and - the closed slot antenna and the open slot parasitic antenna are configured such that: - when the rack (10) is outdoors, the open slot parasitic antenna has a tuning frequency within the specified frequency band, while the closed slot antenna has a tuning frequency outside the specified frequency band, and - When the rear side (RS) of the housing (10) is opposed to the front side of a similar device (HW3-1, HW3-2) or a conductive surface (105) forming a second shield for radiation emitted by the open slot parasitic antenna, the closed slot antenna has a tuning frequency within the specified frequency band, while the open slot parasitic antenna has a tuning frequency outside the specified frequency band.

2. The apparatus of claim 1 , wherein the closed slot antenna comprises: - a longitudinal port (40) made in the side wall (102) of the frame (10) and traversing the side wall, the longitudinal port (40) comprising a first longitudinal surface (41) and a second longitudinal surface (42) facing each other, and - means (50) for applying a ground voltage to a first surface (41) of the longitudinal port (40) and applying the radio frequency signal (RFS) to a second surface (42) of the longitudinal port (40), And the open slot parasitic antenna comprises: - a conductive arm (70) arranged parallel to and close to the longitudinal port (40), the conductive arm (70) having a free end (701) and an end (702) electrically connected to the side wall (102) of the frame.

3. The apparatus of claim 2, wherein a connection end (702) of the arm (70) is electrically connected to the side wall (102) of the housing near one end (44) of the second surface (42) of the longitudinal port (40) that receives the radio frequency signal (RFS).

4. The device according to one of claims 2 and 3, wherein the length (Ls) and height (Hs) of the longitudinal port (40), the length (Lb) of the conductive arm (70), and the orthogonal distance (Db) between the conductive arm and the side wall (102) of the rack (10) are configuration parameters of the closed slot antenna and the open slot parasitic antenna, and wherein the closed slot antenna and the open slot parasitic antenna form a resulting antenna whose gain in the specified frequency band is greater than -5dB when the rack (10) of the device is outdoors and remains greater than -5dB when the back side (RS) of the rack (10) faces a conductive surface (105).

5. The device according to any one of claims 1 to 4, wherein the closed slot antenna and the open slot parasitic antenna are configured such that when the rear side (RS) of the chassis (10) faces a conductive surface (105), radiation from the closed slot antenna dominates over radiation from the open slot parasitic antenna.

6. The device according to one of claims 4 and 5, wherein the length (Ls) of the longitudinal port (40) is close to a quarter of the wavelength of a radio frequency signal (RFS) with a frequency of 2.4 GHz, or is approximately 30.6 mm to within a few millimeters or tenths of a millimeter to take into account the presence of the open slot parasitic antenna.

7. The device according to any one of claims 1 to 6, wherein the frame (10) is made of a conductive non-magnetic material and has magnets (Mi, M1, M2, M3a, M3b, M4a, M4b) for magnetically stacking the device with similar devices (HW3-1, HW3-2).

8. The device according to any one of claims 1 to 7, comprising a radio frequency signal (RFS) injector (50), the radio frequency signal injector comprising: - two substantially parallel flat electrodes (51, 52) connected by a connecting portion (53), A first electrode (51) rests on the first surface (41) of the longitudinal port (40), and a second electrode (52) rests on the second surface (42) of the longitudinal port (40), and - a compression component (55) of flexible and elastic material, which is arranged between the two electrodes (51, 52) and exerts an expansion force on the two electrodes, which causes the first electrode (51) to be pressed against the first surface (41) of the longitudinal port (40) and the second electrode (52) to be pressed against the second surface (42) of the longitudinal port (40).

9. Device according to claim 8, wherein the two electrodes (51, 52) have a large contact surface in contact with the surface (41, 42) of the longitudinal port (40), the length of the large contact surface being at least equal to one quarter of the length of the surface.

10. The device according to any one of claims 8 and 9, wherein the radio frequency signal (RFS) injector (50) comprises an electrical conductor (500) connecting the first electrode and the second electrode (51, 52) and electronic components (C1, C2, C3).

11. An apparatus according to one of claims 1 to 10, wherein the conductive arm (70) comprises a base (703) attached to the side wall (108, 102) of the frame, the base being an extension of the end (70a) of the conductive arm electrically connected to the side wall (102) of the frame (10), the conductive arm further comprising a protruding contact portion (71) resting on a contact surface (108) provided in the side wall (102) of the frame (10).

12. An apparatus according to claim 11, wherein the conductive arm (70) is installed in a state of elastic deflection between a base (703) of the conductive arm attached to the side wall (108, 102) of the frame and a protruding contact portion (71) resting on the contact surface (107) provided in the side wall (102) of the frame, and the elastic deflection applies pressure to the protruding contact portion (71) resting on the contact surface (107).

13. Device according to one of claims 1 to 12, wherein the conductive arm (70) is arranged in a guide member (80) of plastic material, thereby ensuring the parallelism of the arm relative to the side wall (102) of the frame (10).

14. Device according to one of claims 1 to 13, forming a hardware wallet for cold storage of cryptographic keys of the blockchain and comprising a microcontroller (MCU3) and a secure element (SE3).

15. The device according to any one of claims 1 to 14, wherein the designated frequency band is a Bluetooth frequency band or a Wi-Fi frequency band.

16. A method for improving the performance of a radio frequency antenna designed to transmit or receive data in a specified frequency band, the antenna being arranged in an electronic device (HW3), the electronic device (HW3) comprising a frame (10) of conductive material and a wireless communication circuit (MCU3) configured to provide a radio frequency signal (RFS) to the radio frequency antenna, the frame comprising a front side (FS), a rear side (RS), a side wall (102) and a conductive plate (105) on the front side (FS) of the frame, the method being characterized in that: - the radio frequency antenna comprises a combination of a closed slot antenna (40, 50) and an open slot parasitic antenna (70, 102), the closed slot antenna being fabricated in the side wall (102) of the housing and having a radiation axis (Y) substantially perpendicular to the side wall (102) of the housing, and the open slot parasitic antenna having a radiation axis (X) substantially perpendicular to the radiation axis (Y) of the closed slot antenna, - the conductive plate (105) forms a first shield for the radiation emitted by the open slot parasitic antenna, - the closed slot antenna and the open slot parasitic antenna are configured such that: - when the rack (10) is outdoors, the open slot parasitic antenna has a tuning frequency within the specified frequency band, while the closed slot antenna has a tuning frequency outside the specified frequency band, and - When the rear side (RS) of the housing (10) is opposed to the front side of a similar device (HW3-1, HW3-2) or a conductive surface (105) forming a second shield for radiation emitted by the open slot parasitic antenna, the closed slot antenna has a tuning frequency within the specified frequency band, while the open slot parasitic antenna has a tuning frequency outside the specified frequency band.

17. The method according to claim 16, wherein: - the closed slot antenna comprises a longitudinal port (40) made in and passing through a side wall (102) of the housing (10), the longitudinal port (40) comprising a first longitudinal surface (41) and a second longitudinal surface (42) facing each other, and means (50) for applying a ground potential to the first surface (41) of the longitudinal port (40) and applying a radio frequency signal (RFS) to the second surface (42) of the longitudinal port (40), and the closed slot antenna has a radiation axis (Y) substantially perpendicular to the side wall (102) of the housing, and - The open slot parasitic antenna is made by arranging a conductive arm (70) parallel to and close to the longitudinal port (40), the conductive arm (70) having a free end (701) and an end (702) electrically connected to the side wall (102) of the frame.

18. The method of claim 17, comprising the step of connecting an end (702) of the arm (70) to the side wall (102) of the housing near one end (44) of the second surface (42) of the longitudinal port (40) that receives the radio frequency signal (RFS).

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