Multi-role unlocking of data storage devices

Abstract

The present invention discloses a data storage device, which includes a data path, an access controller and a data repository. The data path includes: a data port configured to transmit data between a host computer system and the data storage device; a non-volatile storage medium configured to store encrypted user content data; and an encryption engine connected between the data port and the storage medium and configured to decrypt the encrypted user content data stored on the storage medium using an encryption key in response to a request from the host computer system. The access controller is configured to store multiple entries associated with multiple corresponding registered devices on the data repository. The multiple entries include authorization data indicating an encryption key, which selectively provides user access rights or manager access rights for each of the multiple registered devices.

Description

Technical Field

[0001] The present disclosure relates to data storage devices that can be locked and unlocked. Background Art

[0002] Data encryption enables relatively safe storage on data storage devices, such as block data storage devices that can be connected via a universal serial bus (USB) cable. However, the user experience is often disappointing because the setup of passwords, keys, etc. is cumbersome and complicated for technically unskilled users. If encryption is used, the storage of keys and passwords is often unsafe. Therefore, many users do not effectively use existing encryption technologies, resulting in exposure of confidential data.

[0003] Furthermore, if multiple roles are defined, such as a user role with limited access rights and an administrator role with full access rights, management of the data storage device will be more efficient and more secure. However, common solutions used in operating systems, such as access control lists based on login credentials, are impractical for data storage devices that are moved between different host computer systems. It is desirable to define multiple roles within the data storage device without using an external operating system and access control lists. Summary of the invention

[0004] The present disclosure provides a data storage device that enables definition of multiple roles for unlocking and configuring the data storage device based on an encryption key stored on the data storage device. The encryption keys between the authorization device and the manager device are different. The encryption key ("user key") provided in response to a connection from the authorization device enables decryption of user content data stored on the data storage device, but cannot read configuration data of other devices. The encryption key ("manager key") provided in response to a connection from a manager device enables decryption of user content data stored on the data storage device and enables reading of configuration data.

[0005] A data storage device is disclosed herein, which includes a data path, an access controller, and a data repository. The data path includes: a data port configured to transmit data between a host computer system and the data storage device; a non-volatile storage medium configured to store encrypted user content data; and an encryption engine connected between the data port and the storage medium and configured to decrypt the encrypted user content data stored on the storage medium using an encryption key in response to a request from the host computer system. The access controller is configured to store multiple entries associated with multiple corresponding registered devices on the data repository. The multiple entries include authorization data indicating an encryption key, which selectively provides user access rights or manager access rights for each of the multiple registered devices.

[0006] In some embodiments, user access rights enable decryption of encrypted user content data; and restrict reading of authorization data associated with other registered devices.

[0007] In some embodiments, administrator access rights enable decryption of encrypted user content data; and enable reading of authorization data associated with other registered devices.

[0008] In some embodiments, each entry includes authorization data indicating a user key for providing user access rights or indicating a manager key for providing manager access rights.

[0009] In some embodiments, each entry includes a key field that stores authorization data indicative of only one of the user key and the manager key.

[0010] In some embodiments, the user key can be derived from the manager key via a one-way function.

[0011] In some embodiments, the manager key enables reading of authorization data associated with other registered devices; and the user key, which can be derived from the manager key, enables decryption of encrypted user content data.

[0012] In some embodiments, the user key is the same for multiple entries that provide the user with access rights.

[0013] In some embodiments, the manager key is the same for multiple entries that provide manager access rights.

[0014] In some embodiments, the authorization data for each entry in the plurality of entries is encrypted based on a private key stored on a registered device in the plurality of registered devices associated with the entry.

[0015] In some embodiments, the private key is different for each registered device in the plurality of registered devices.

[0016] In some embodiments, each entry for which user access is provided includes encrypted metadata encrypted by a metadata encryption key; the metadata encryption key is based on a secret key stored on each of the multiple registered devices and is different for each entry; and the metadata encryption key is stored in the entry encrypted based on the manager key to provide access to the metadata in response to obtaining the manager key.

[0017] In some embodiments, the access controller is further configured to generate a challenge to one of the multiple registered devices; send the challenge to the one of the multiple registered devices via a communication channel different from the data path; receive a response to the challenge from the one of the multiple registered authorized devices via the communication channel; and decrypt the authorization data based at least in part on the response to obtain an access key, the access key being one of a manager key that provides manager access rights and a user key that provides user access rights.

[0018] In some embodiments, the challenge is based on the authorization data.

[0019] In some embodiments, the challenge is based on a public key of the one of the plurality of registered devices.

[0020] In some embodiments, the access controller is configured to encrypt the encryption key to generate the authorization data.

[0021] In some embodiments, the access controller is further configured to perform the following steps for each of the multiple entries: generate a temporary private key and a corresponding temporary public key; encrypt the encryption key based on the temporary private key and an unlocking public key, the unlocking public key corresponding to the unlocking private key stored on the corresponding registered device; discard the temporary private key; and store the temporary public key and the unlocking public key.

[0022] In some embodiments, the data storage device is configured to register with the host computer system as a block data storage device.

[0023] A method for providing access rights to a data storage device including a data repository is also disclosed. The method includes: storing multiple entries associated with multiple corresponding registered devices on the data repository, wherein the multiple entries include authorization data indicating an encryption key that selectively provides user access rights or manager access rights for each of the multiple registered devices; connecting to a registered device in the multiple registered devices; selecting an entry in the multiple entries that is associated with the connected registered device; and enabling use of one of the encryption keys of the selected one of the multiple entries to provide user access rights or manager access rights for the one of the multiple registered devices.

[0024] The present invention also discloses a data storage device, which includes: a device for storing multiple entries associated with multiple corresponding registered devices on a data repository, wherein the multiple entries include authorization data indicating an encryption key, which selectively provides user access rights or manager access rights for each of the multiple registered devices; a device for connecting to a registered device among the multiple registered devices; a device for selecting an entry among the multiple entries associated with the connected registered device; and a device for enabling the use of an encryption key in the encryption key of the selected one of the multiple entries to provide user access rights or manager access rights for the one of the multiple registered devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Non-limiting examples will now be described with reference to the following drawings:

[0026] Figure 1 A data storage device according to one embodiment is shown.

[0027] Figure 2 According to one embodiment, Figure 1 A section of the configuration memory of a data storage device.

[0028] Figure 3 According to one embodiment, Figure 1 The control flow between the authorization device and the access controller.

[0029] Figure 4 A certificate issued by a data storage device and sent by an authorization device to the data storage device to unlock the data storage device is shown according to one embodiment.

[0030] Figure 5 A method for providing access rights to a data storage device according to one embodiment is shown. DETAILED DESCRIPTION

[0031] Figure 1 1 shows a data storage device (DSD) 100 including a data path 101 and an access controller 102 according to one embodiment. The data path 101 includes a wired data port 103, which is connected to the Figure 1 104 and DSD 100. In other embodiments, the data path 101 includes a wireless data port (not shown) for wirelessly transmitting data between the host computer system 104 and the DSD 100. The DSD 100 is registered with the host computer system 104 as a large-capacity data storage device that provides functionality to the operating system of the host computer system 104 of a block data storage device. The DSD 100 also includes a non-transitory storage medium 105 for storing encrypted user content data, noting that user content data is data that a user typically wants to store on the DSD, such as files including image files, documents, video files, etc. The storage medium can be a solid-state drive (SSD), a hard disk drive (HDD) with a rotating disk, or other non-volatile storage medium. In addition, the storage medium can be a block data storage device, which means that the user content data is written to the storage medium 105 in the form of blocks and read from the storage medium 105 in the form of blocks.

[0032] Command Set

[0033] In one example, the storage medium 105 includes an encryption engine 106 in the form of an application specific integrated circuit and / or a programmable integrated circuit that encrypts data to be stored on the storage medium 105 and decrypts data to be read from the storage medium 105. In such examples, the storage medium may provide a Small Computer System Interface (SCSI) or Advanced Technology Attachment (ATA) command set in accordance with the optical specification of the Trusted Computing Group (TCG).

[0034] Program code stored on the encryption engine 106 enables the encryption engine 106 to receive, interpret and execute commands received from the host computer system 104. For example, the encryption engine 106 can be configured to implement the standard ATA or Serial ATA (SATA) and / or ATA Packet Interface (ATAPI) command set, which can be obtained from Technical Committee T13, noting that the same functionality can be implemented in TCG Opal, SCSI and other proprietary architectures. The command set includes a READ SECTORS command, and the command input is a count of sectors and a starting sector (note that "sector" is used synonymously with "block" in this article). Therefore, there is a corresponding write command. It should be noted that a data storage device driver is installed on the host computer system 104. The data storage device driver (not shown) uses the command set to provide advanced services to the operating system, such as file read functions. In some examples, the data storage device driver is a generic driver provided as part of the operating system, and does not support device-specific encryption commands because the encryption functions are hidden from the host computer system 104 and are processed internally within the DSD 100, as described below. This means that there is no need to install additional drivers to use the full functionality disclosed herein.

[0035] The command set provided by the encryption engine 106 to the data port 103 (but not forwarded to the host computer system 104) may include a command set from the ATA SECURITY feature set. Specifically, the command set may include the command SECURITY SETPASSWORD or a corresponding command from TCG Opal to set a password for reading user content data and writing user content data to the storage medium 105.

[0036] In this sense, the encryption engine 106 is connected between the data port 103 and the storage medium 105, and is configured to use the encryption key to encrypt the user content data to be stored on the storage medium 105 and decrypt the encrypted user content data stored on the storage medium 105 in response to a request from the host computer system 104. In some examples, the ATASECURITY feature set is only used by the data port 103, and not by the host computer system 104. That is, the access controller 102 provides the necessary input for the data port 103 to issue the ATASECURITY command to the encryption engine 106. For example, the access controller 102 can provide the key to the data port 103, and then the data port 103 forwards the key to the encryption engine 106 via the SECURITY SET PASSWORD command. The interface between the access controller 102 and the data port 103 can be an inter-integrated circuit (I2C) bus, which is particularly useful in the case where the bus has been implemented in an existing chip. However, many other communication architectures can be used, including bus architectures, point-to-point architectures, serial architectures, parallel architectures, memory-based architectures, and other architectures.

[0037] Please note that Figure 1 The separation of functions in the dedicated chip shown is only one possible exemplary implementation. Therefore, functions can be further combined or split. For example, the data port 103 can be integrated with the access controller 102 into a single chip with a single core. In other cases, the data port 103 and the access controller 102 can be integrated with the encryption engine 106 into a single dedicated chip with a single core. Of course, all chips can have multiple cores.

[0038] In one example, the following components are used:

[0039] Data port 103: USB 3.1 Gen 2 10 Gigabit per second (Gb / s) interface

[0040] Access Controller 102: nRF52840 System-on-Chip (SoC) from Nordic Semiconductor

[0041] Note that for the functionality disclosed herein, the access controller 102 plays a primary role and will be described in more detail below, again noting that in other examples, tasks may be split into separate chips. When reference is made to the "configuration" of the access controller 102 or the access controller 102 is "configured" to perform a certain step, this should be understood to refer to program code stored on a program memory (not shown for clarity) on a non-volatile memory in the DSD 100 and executed by the access controller 102.

[0042] In other examples, some or all of the steps disclosed herein may be performed by hardware circuits without program code. Specifically, for performance and security reasons, cryptographic primitives may be implemented by dedicated hardware circuits. For example, particularly computationally demanding commands (such as elliptic curve multiplication or exponentiation) may be implemented by an arithmetic logic unit (ALU) specifically designed for that calculation, so that the calculation can be performed in a single or fewer number of processor cycles than using a sequential program in a general-purpose microcontroller. It should also be noted that the chips included in the DSD 100 are microcontrollers, which means that in this context, they do not run under an operating system that provides a hardware abstraction layer, but rather program code acts directly on hardware circuits. Although elliptic curve encryption is used as an example in this article for computational efficiency and security reasons, it should be noted that other public key cryptographic systems, such as the Rivest-Shamir-Adelman (RSA) cryptographic system, may also be used.

[0043] return Figure 1 In addition to the host computer system 104, there are multiple devices located external to the DSD 100 and that play a role in unlocking the DSD 100 and providing keys to the encryption engine 106, so that the plaintext decrypted data can ultimately be provided to the host computer system 104.

[0044] Specifically, there is a first manager device 110, which in most examples is a mobile phone. An application (app) installed on the manager device 110 performs the following steps. As such, the following steps may be implemented in software by the manufacturer of the DSD 100 and distributed to the manager devices 110 via a commonly accessible application store (such as Apple's App Store or Google Play). The application installed on the manager device 110 performs the steps of acquiring ownership of the DSD 100, at which point all data on the DSD 100 is erased or otherwise rendered inaccessible. For example, the data may be cryptographically erased by securely deleting all encryption keys stored on the DSD 100.

[0045] For simplicity, the present disclosure describes the steps as being simply performed by the manager device 110 if they are implemented by an application. The manager device 110 sets up the DSD 100, which means generating various different keys to support the processes disclosed herein. The manager device 110 registers the user device 111 with the DSD, so that the user device 111 is subsequently referred to as an "authorized device" 111. In most examples, the authorized device 111 is also a mobile phone, which has an application installed that implements the steps described as being performed by the authorized device 111. However, other types of devices can be used as authorized devices, which will be explained below with respect to beacons and key cards.

[0046] Taking Ownership

[0047] After purchase, unpacking, and powering up, the first step in using the DSD 100 is to install the application on the manager device 110 and register the device as a manager device 110. For this process, the manager device 110 obtains a unique identifier for the DSD from the DSD. This unique identifier is called an identity key (IDK). Figure 1 In the example shown, the identity key is encoded as a quick response (QR) code 112 that is attached to the outer surface of the DSD 100. An application installed on the manager device 110 has access to the camera and has a software module that extracts the encoded information from the image of the QR code 112. The manager device 110 captures the image of the QR code 112 using the camera and decodes the identity key of the DSD 100 from the QR code. In one example, the QR code encodes a uniform resource locator (URL). In this case, a universal application can capture the QR code, which then automatically directs the phone to an application store where the application can be downloaded. The URL also includes the identity key so that once the application is installed, the application can decode the identifier.

[0048] In another example, the manager device 110 may read another tag or NFC chip attached to or integrated with the DSD 100 to obtain the identity key. Using the identity key, the manager device 110 may then initiate communication with the DSD 100 and, in particular, the access controller 102, such as wirelessly (e.g., via Bluetooth).

[0049] Recovery Key

[0050] Upon taking ownership of DSD 100, access controller 102 generates a recovery key and provides the recovery key to manager device 110. The recovery key may then be stored on secure storage 113 or printed and locked away. Finally, backup manager device 114 may use the recovery key to assume the administrator role previously held by manager device 110.

[0051] Registration of authorized devices

[0052] Once the DSD 100 is initially configured during the acquisition process, the manager device 110 registers the authorized device 111. Typically, there may be multiple authorized devices registered with a single DSD 100, so the manager device 110 registers the authorized device as one of the multiple authorized devices. More specifically, the access controller 102 receives a public key associated with a private key stored on the user device 111 from the manager device 110. The manager device 110 itself may have received the public key from the user device 111 via email, by scanning a QR code displayed on the user device 111, or in any other manner. At this point, the device 111 is not yet authorized, and is therefore referred to simply as "user device 111". Once the user device 111 is authorized, it is referred to as "authorized device 111". The access controller 102 creates authorization data indicating that the user device 111 is an authorized device (described below) and stores the authorization data associated with the public key on the configuration memory 115 to register the user device 111 as one of the multiple authorized devices. This means that keys and other data associated with the authorizing device 111 are created and stored as described below. The user can then use the authorizing device 111 to unlock the DSD 100 simply by placing the authorizing device 111 within wireless communication range (e.g., Bluetooth range). Again, the steps performed by the authorizing device 111 are encoded in an application installed on the authorizing device 111. Depending on configuration parameters, the user may be required to unlock the authorizing device 111 before the DSD 100 can be unlocked.

[0053] More specifically, the access controller 102 has access to a non-volatile configuration data repository, such as configuration memory 115, which may be flash memory external to the access controller 102 (but may equally be integrated into the access controller 102). The configuration memory 115 may also store program code that implements the steps described herein as being executed by the access controller 102. It is noted that some of the examples herein are configured to assume that an attacker may easily isolate and read out the contents of the configuration memory 115, but should not be able to use that information to decrypt user content data. That is, in those examples, no keys are permanently stored in plain text on the configuration memory 115 or elsewhere on non-volatile memory in the DSD 100.

[0054] Once the encryption keys are provided in plain text, they are stored only in volatile memory (not shown). This means that powering down the DSD 100 erases all encryption keys stored in plain text. Additional circuitry may be provided to reset all residual charge upon power down, power up, or external reset, making it physically impossible to recover any information from the volatile memory in practice. In many cases, a user disconnecting the USB cable from the host computer system 104 results in a power down and erase of all volatile memory. In other examples, a secondary power supply is used that requires disconnection to power down the DSD 100 to delete the volatile memory.

[0055] Challenge-Response

[0056] The configuration memory 115 has data stored thereon that is specific to the registered authorization device 111. This data may be referred to as an identifier of the authorization device 111 or as a public key associated with a corresponding private key stored on the authorization device 111. The public key may be a "transmission public key" (TPK) and is generated by the authorization device 111 when the application is first started by executing the elliptic curve cryptography (ECC) primitive ECC-Pub ({transmission private key}). (Recall that, although elliptic curve cryptography is used as an example in this article for reasons of computational efficiency and security, it should be noted that other encryption techniques may also be used.) The corresponding private key is stored on the authorization device 111. The access controller 102 is configured to use an identifier (e.g., a transmission public key) or to generate and store an additional public key to generate a challenge to the authorization device 111. It should be noted here that the challenge is unique because each challenge is different, so that subsequent challenges are different from any previous challenges. As described below, this is achieved by multiplying the stored data by a random blinding factor. The access controller 102 then sends the challenge to the authorization device 111 over a communication channel that is different from the data path. For example, the data path may include a wired USB connection, while the communication channel between the access controller 102 and the authorization device 111 is a wireless (eg, Bluetooth) connection.

[0057] In one example, a re-registration process is performed in response to the authorization device first connecting to the DSD 100 after the authorization data is created and stored on the configuration memory 115 in association with the public key of the authorization device 111 received from the manager device 110. During the re-registration process, the DSD 100 updates the authorization data and, as described below, may request that the authorization device 111 generate an unlock public key (and a corresponding unlock private key) in addition to transmitting the public key. The authorization device 111 then provides the unlock public key to the access controller 102.

[0058] This has the following advantages: two corresponding private keys (transmission private key and unlocking private key) can be stored separately on the authorization device, and the two keys can have different access policies. For example, even if the authorization device 111 is locked (e.g., by screen lock or timeout), the transmission public key can be accessed at any time to allow continuous communication between the authorization device 111 and the DSD 100. However, in order to unlock the DSD 100, the access policy of the unlocking private key may require the user to unlock the authorization device 111, enter a personal identification number (PIN), provide biometrics or other authentication. In this way, a stolen authorization device cannot unlock the DSD 100. Since unlocking the DSD 100 is only performed once when the DSD 100 is powered on, the increased security does not significantly reduce user convenience.

[0059] Authorized device 111 may calculate a response to the challenge that cannot be calculated by any other device not registered with the DSD. More specifically, a device that does not have access rights to the data corresponding to the identifier stored on configuration memory 115 cannot calculate the correct response. For example, authorized device 111 calculates the response to the challenge using a stored unlock private key associated with a corresponding unlock public key stored on configuration memory 115.

[0060] The access controller 102 receives a response to the challenge from the authorization device 111 via the communication channel. It should be noted here that if the access controller 102 simply verifies the response to the challenge and, upon success, reads the encryption key from the configuration memory 115, the encryption key will be stored in plain text, which is undesirable because it will enable an attacker to deassemble the DSD 100 and read the key from the configuration memory 115 to access the user content data stored on the storage medium 105.

[0061] Calculate the key

[0062] Therefore, instead, the access controller 102 computes the encryption key based at least in part on the response from the authorization device 111. This means that the encryption key is not a pure function of the response, but involves other values ​​as described in more detail below. In summary, the encryption key is stored in encrypted form on the configuration memory 115, and the calculation of the secret to decrypt the encryption key is enabled based on the response of the private key stored on the authorization device.

[0063] Throughout this disclosure, reference may be made to the "encapsulation" of a key, which simply means that a key is encrypted by another key (i.e., by a "secret"). In many cases of "encapsulation", the encryption is symmetric, such that there is a single secret (key) that can decrypt the encrypted key (there is no public key associated with the secret). In one example, the symmetric encryption uses Advanced Encryption Standard (AES) primitives.

[0064] Finally, the access controller 102 provides the encryption key to the encryption engine 106 (via the data port 103 in this example) to decrypt the encrypted user content data stored on the storage medium 105 of the DSD 100. As described above, once the access controller 102 has calculated the encryption key, the access controller 102 provides the encryption key in plain text to the data port 103, and the data port 103 issues a SECURITY SET PASSWORD command including the encryption key to the encryption engine 106.

[0065] Note that where reference is made to "unlocking" the device, this may refer to the entire process described above, including the challenge, the response to the challenge, and the sending of an encryption key to the encryption engine 106 to allow a plain text read command issued by the host computer system. In other examples, the challenge and the response to the challenge are considered part of a separate "connection" step. During the following "unlock" step, the access controller 102 then sends the encryption key to the data port 103 to allow access to the user content data.

[0066] It is worth noting that, in addition to this, it is possible for an attacker to eavesdrop on the transmission of the key from the access controller 102 to the data port 103 and then to the encryption engine 106. However, the transmission of the key is not over a public network, so such eavesdropping would require gaining access to and disassembling the unlocked DSD without removing power from the DSD 100. This scenario can be discarded as a threat because in this scenario, the user content data is available on the host computer system 104 anyway. In other words, while the DSD 100 is connected and unlocked, the data is available to both the legitimate user and the attacker. But once the user disconnects the DSD from the host computer system 104, such an eavesdropping attack is no longer possible. Therefore, this attack will not be considered further.

[0067] For the sake of completeness, it is noted that once the encryption engine 106 has received the encryption key, the host computer system 104 can issue a normal READ SEGMENT command and transparently access the encrypted data without any perceptible difference to accessing an unencrypted device. This is particularly true if the encryption engine has a hardware encryption module to achieve encryption and decryption at or above the read and write speeds of the storage medium 105 and / or data port 103. However, the user can disconnect the DSD 100 to lock it. In this way, the DSD 100 can be carried by the user through an unsecured location where the DSD 100 may be lost or stolen, but it is difficult for others to decrypt the encrypted user content data stored on the storage medium 105. If the user has the DSD, the user can connect it to the second host computer system 116, conveniently unlock the DSD 100 using the user's authorized device 111 (e.g., a phone), and easily access the encrypted user content data stored on the storage medium 105.

[0068] For user convenience, data port 103 may be configured so that if the DSD is locked, it registers with host computer system 104 as a large-capacity data storage device with no storage media present, similar to an SSD card reader with no card inserted. Once an authorized device 111 is connected to DSD 100 and DSD 100 is unlocked, data port 103 switches to the storage media present, similar to a card reader with an SSD card inserted. Such a configuration will prevent the host computer system 104 operating system from generating any warnings about data being inaccessible or access being denied. Instead, all user interactions will be performed by an application installed on the authorized device, which is fully controlled by the manufacturer of the DSD, so the user experience can be optimized. Figure 1 As shown, there may also be mobile phones acting as authorization devices 117 and 118.

[0069] Beacons and key fobs

[0070] Consider Again Figure 1, it can be seen that there are additional devices, such as beacons 120 and key fobs 121. These devices may also be considered "authorized devices" because they may operate substantially the same as the authorized device 111. Prior to initial registration by the manager device 110, these devices are referred to as "devices to be authorized." When reference is made to "user devices" herein (primarily describing the mobile phone 111 prior to initial registration), this also applies to the beacons 120 and key fobs 121, unless otherwise noted, such as where user input is required. The beacons 120 and key fobs 121 also have their own securely stored private keys so that they can respond to challenges specific to one beacon or key fob. However, since there is no user input for the beacons 120 and key fobs 121, the initiation of communication may be slightly different. More specifically, the beacons 120 and key fobs 121 may periodically send announcements to broadcast their presence, and the DSD 100 then initiates communication with the beacons 120 and / or key fobs 121, which prompts them to send their transmission public keys. This is in contrast to the authorization device 111 which sends a transmission public key to the DSD 100 to initiate communication.

[0071] In another example, the beacon 120 is in a deactivated state when it is powered on and needs to be activated by the manager device 110 or the authorization device 111. This activation may follow a similar process to unlocking the DSD 100. That is, the manager device 110 or the authorization device 111 or both register with each beacon 120 using its transmission public key and respond to a challenge as described herein. Thus, a device may register with one of the beacons 120 and / or the key fob 121 as a manager device or an authorization device without registering with the DSD 100 itself. If the response to the challenge is valid, the beacon 120 unlocks the DSD 100. In yet another example, the beacons 120 register with each other such that the manager device 110 and / or the authorization device 111 need only activate one of the beacons 120 and the remaining beacons automatically activate. In other words, the activation is "propagated" through the beacon network as long as the beacons are within range of each other.

[0072] Note that the only information that authorized devices 111, 117, 118, 120, and 121 provide to manager device 110 for registration is a public key for each device. In other words, each device provides its own public key that corresponds to a private key securely stored on that device. Therefore, if an attacker intercepts the initial communication between one of devices 111, 117, 118, 120, and 121 and manager device 110, the only information the attacker can obtain is the public key. As the name implies, the public key is not a secret and can be well known. Therefore, the attacker does not gain any advantage. In addition, manager device 110 cannot use the public key to access anything else related to the authorized device. For example, a manager device cannot decrypt or unlock any other data storage device with which other manager devices have registered the authorized device.

[0073] The access controller 102 receives the public key of the authorized device from the manager device 110 and generates authorization data. The access controller 102 stores the authorization data on the configuration memory 115 and waits for the authorized device to connect for the first time. At the first connection, the access controller 102 performs a challenge-response to the authorized device and, upon success, updates the authorization data to indicate that the authorized device is now fully registered. This first connection process is referred to herein as "re-registration," and details of generating authorization data and re-registration are provided below.

[0074] Elliptic Curve Cryptography

[0075] In one example, the challenge generated by the DSD 100 and sent to the authorization device 111 is based on elliptic curve cryptography. This has the advantage of shorter keys, resulting in more efficient communication and storage. In addition, a large number of phones currently on the market provide dedicated elliptic curve cryptographic functions within a secure hardware module. The secure hardware module securely stores the user's private keys and executes cryptographic primitives within the secure hardware module without the keys leaving the secure hardware module and being sent to a general-purpose processor core, where the keys may be subject to unauthorized retrieval attacks. In one embodiment, the secure hardware module includes an independent processor that executes its own microkernel that cannot be directly accessed by the operating system or any program running on the phone. The secure hardware module may also include a non-volatile storage device for storing a 256-bit elliptic curve private key. In one embodiment, the secure hardware module is a Secure Enclave coprocessor available on some Apple devices.

[0076] Authorized device data record

[0077] Figure 2 1 shows a cross section of configuration memory 115 according to one embodiment. More specifically, Figure 2 A record 201 in the configuration memory 115 is shown, which is associated with one of the multiple authorized devices and is referred to herein as "authorization data". Additional data records for additional authorized devices are schematically indicated as empty dashed boxes, but details are not considered when they operate in a similar manner to record 201. Specifically, each additional data record includes authorization data, which is generated by the access controller 102 in response to receiving a public key of a user device from the manager device 110, and then updated during the first connection of the user device (hereinafter referred to as "authorized device"). For convenience, the data structure of the configuration memory 115 is referred to as a "table" including one or more "records", each of which relates to a registered authorized device and each record has multiple fields. However, it should be noted that other data structures can be used, such as JavaScript Object Notation (JSON), Extensible Markup Language (XML), binary format, etc. In one example, each entry has a fixed length, and the table has a fixed number of rows (i.e., entries). In the present disclosure, a "record" may also be referred to as a "row" or "entry".

[0078] Record 201 includes a field for a pre-authorization key 202, which is used in response to the first connection of the authorized device 111 to the DSD 100. During this first connection, the access controller 102 performs a number of steps referred to as "re-registration," as described in more detail below. The pre-authorization key 202 is generated by an identifier of the authorized device 111 (e.g., a transmission public key). For example, the access controller 102 can generate the pre-authorization key 202 by applying a key derivation function together with an authorized device slot key to the derivation function, the key derivation function using the x-coordinate of the transmission public key as an input parameter, the authorized device slot key as a salt value. The authorized device slot key can be a pseudo-random number (e.g., 16 bytes) stored on the configuration memory 115, and can be used to encrypt data in an authorized device certificate so that only the issuing DSD 100 can recover the information.

[0079] At this point, it can be said that the records stored on the configuration memory 115 are indexed by the pre-authorization key 202 based on the identifier of the authorized device (e.g., the transmission public key). Figure 4 As described, during re-registration, the index of record 201 may be stored as a slot number in the certificate and the pre-authorization key 202 may be replaced with a random value at this time to make the configured DSD indistinguishable from a new device leaving the factory even in possession of the transport public key.

[0080] Record 201 also includes fields for a first copy of a metadata encapsulation key (MWK) 203 and a pre-authorization metadata encapsulation key (PMWK) 214. Some of the fields in record 201 are encrypted, which are indicated by double-line boxes, where a single solid box within the double-line box indicates a "payload", such as metadata encapsulation key 203 and pre-authorization metadata encapsulation key 214. The corresponding encryption key used to encrypt the payload is noted at the bottom of the double-line box. Thus, for example, metadata encapsulation key 203 is encrypted by authorized device metadata key (ADMK) 204. It should be noted that each encrypted box may include an additional random number concatenated with the payload data. This ensures that even possession of encrypted data (such as the transmission public key of an authorized device) cannot distinguish the encrypted entry from the random data.

[0081] The record 201 also includes a field for authorized device metadata (ADM) 205, which is a concatenation of a device type 206 (e.g., recovery key, key fob, beacon, phone, computer, watch, etc.), a role 207 of the device ("administrator" or "user"), a name 208 of the device (e.g., "John's phone"), a transport public key 209, unlock key metadata 210 (e.g., whether a fingerprint, PIN, or key restriction is required for unlocking), a temporary public key 211, and an unlock public key 212. In one embodiment, the temporary public key 211 is an elliptic curve public key generated from a random temporary private key (EPK) using an elliptic curve cryptography (ECC) primitive ECC-Pub (EUK). The temporary private key is not stored on the configuration memory 115 or on the authorized device 111, but is discarded after the temporary public key is created. This means that the temporary private key is not stored on non-volatile memory, but only on volatile memory. Therefore, a power failure to the memory results in a complete and irrecoverable loss (e.g., destruction) of the temporary private key. The unlock public key 212 corresponds to the unlock private key stored on the authorizing device 111 , and is generated by the authorizing device 111 and provided to the access controller 102 .

[0082] The authorized device metadata (concatenated with an additional random number) is encrypted by a metadata wrapping key (MWK) 213, which is also stored in encrypted form at 203. The primary purpose of storing the encrypted metadata wrapping key 203 in entry 201 is to allow a manager user with access rights to the authorized device metadata key 204 to access the encrypted authorized device metadata 205. If the manager does not have access to the metadata wrapping key, the manager will not be able to retrieve any information from the DSD 100 about which authorized devices are currently registered. In one example, the authorized device metadata key 204 is a single key for all authorized devices and is stored encrypted by the manager key. The manager key can be a pseudo-random value (e.g., 32 bytes) and is generated by the access controller 102 in response to the storage medium 105 being erased. The manager key is encrypted and stored for each paired manager device 110 / 114.

[0083] Record 201 also includes a field for a second copy of the device role 220 concatenated with a second copy of the user key 221 and the metadata encapsulation key 222. Note that the roles 207 / 220 and metadata encapsulation keys 203 / 222 are stored in two copies that are identical but encrypted using different keys. The purpose of storing two copies of the roles 207 / 220 is to enable the access controller 102 to verify the roles during connection (in response to the authorization device metadata being decrypted) and during unlocking (in response to the user key 221 being decrypted). The purpose of storing the first copy of the metadata encapsulation key 203 is to provide it to manager devices that have access rights to the authorization device metadata keys. The purpose of the second copy of the metadata encapsulation key 222 is to provide it to pre-authorized devices during the first connection. The concatenated values ​​220, 221, 222 are encrypted together by a temporary unlocking secret (EUS) 223, which is initially generated by the Diffie-Hellman method using a temporary private key corresponding to the temporary public key 211 and the unlocking public key 212. The temporary unlocking secret 223 can be recovered using the temporary public key 211 and the associated unlocking private key stored on the authorized device 111 and corresponding to the unlocking public key 212. In other words, the temporary unlocking secret 223 can be generated when the authorized device 111 is first connected to the DSD 100 using the temporary private key and the unlocking public key 212. Note that the temporary private key itself is not stored, but the temporary unlocking secret 223 can still be recovered as described above. This means that the user key 221 can be decrypted based on the response from the authorized device. Note that the user key 221 is the same for all authorized devices and can be used to decrypt user content data. This does not necessarily mean that the user key itself decrypts the user content data. There may also be a key that the user key decrypts and the final key decrypts the user content data. The terms "decrypting user content data using a key" and "enabling decryption of user content data" refer to indirect encryption via multiple keys in a chain. In contrast, "key decryption data" refers to directly decrypting data using a key, such as modular multiplication of encrypted data with a key. Here, user key 221 is used to indirectly decrypt data and can be the starting point of a chain of keys that are decrypted in sequence until, at the end, the chain ends at the key that decrypts the user content data. Although in most examples disclosed herein, temporary unlocking secret 223 decrypts user key 221, encryption keys can also be derived from responses to challenges in other ways. For example, responses to challenges can be used directly as encryption keys to decrypt user content data.

[0084] This distribution of keys and metadata enables configuration in which the entire configuration information about authorized devices, manager devices, and other aspects is stored on the DSD 100 itself. However, the authorized devices require the keys stored on the corresponding authorized devices to unlock the DSD 100. If an unregistered user who does not have access to any keys wants to access the entire configuration of the device, such as retrieving a list of registered devices, the unregistered user will only need the recovery key to register as a manager device and gain access to the manager key. The DSD 100 can then use the manager key to provide the entire contents of the configuration memory 115 to the new manager device. In addition, there may be two manager devices, and both can register or remove authorized devices. Other manager devices will be able to obtain configuration updates by synchronizing their own records with the data stored on the configuration memory 115. In some examples, the DSD 100 is configured to erase the records 201 of all authorized devices (but not delete the user content data or user keys 221, which may be stored in encrypted form on the configuration memory 115, separate from the entries 201 and other entries) if the recovery key is used to gain access but this is a policy decision.

[0085] Figure 3 The control flow 300 between the authorization device 111 and the access controller 102 according to one embodiment is shown. First, the authorization device 111 initiates the connection method by sending 301 its transmission public key. This step can be easily replayed by an attacker. The access controller 102 then replies 302 with a request for a certificate, and in response to the request, the authorization device 111 sends 303 the certificate previously obtained from the access controller 102 through the re-registration process.

[0086] Certificate

[0087] Figure 4 A certificate 400 is shown that is issued by a data storage device 100 and sent to the data storage device by an authorization device 111 to unlock the data storage device, according to one embodiment. In this example, the certificate 400 includes a plurality of type-length-value (TLV) fields, where the type value indicates the kind of field that is part of the certificate, the length is the size of the value field (usually in bytes), and the value is a variable-sized series of bytes that contains the data for that portion of the certificate.

[0088] The certificate 400 begins with a TLV atom which indicates the type of certificate that follows. This is called the certificate role 401 and has a 2-byte value to indicate that this is an authorized device certificate.

[0089] The certificate 400 belongs to a certificate chain. The access controller 102 uses the chain to verify and authenticate the certificate 400. In order to indicate which chain the certificate 400 belongs to, the certificate 400 has a 4-byte root certificate identifier (ID) 402. The certificate identifiers of each certificate in the certificate chain are the same. Unmatched certificate identifiers indicate invalid certificates. In one example, the root certificate identifier indicates whether the certificate chain is a production or development certification chain. In other examples, other groups may be indicated by corresponding certificate identifiers.

[0090] Certificate 400 also includes a 1-byte indicator of certificate depth 403. The depth of a certificate is defined as its distance from the root certificate within the certificate chain. The root certificate is defined to have a depth of zero. When processing a given certificate chain, the depth field is verified to ensure the integrity of the chain.

[0091] The certificate 400 also includes a 64-byte certificate transport public key 404 (e.g., according to the National Institute of Standards and Technology (NIST) P-256 elliptic curve). Each certificate is represented / indexed via the transport public key. Each type of public key will have its own dedicated tag type. That is, the tag type will represent the cipher suite used to generate the transport public key, such as the P-256 cipher suite.

[0092] The certificate 400 also includes a data field 405 (explained below) and is authenticated via a signature 406. The access controller 102 receives the certificate 400 and verifies the signature before trusting or using any of the contents of the certificate. To enable signature verification, a 64-byte signer public key 407 is provided as part of the certificate. The signature 406 itself is 64 bytes in length and is calculated over all previous TLVs 401-405, 407 encountered within the certificate, regardless of whether they are recognized by the specific implementation. More specifically, the signature 406 is derived from a hash of the certificate data. The specific data of the signature is certificate-related, but contains all TLVs used to represent the certificate, including unrecognized TLVs. The key used to generate the signature is a logical identity key and is associated with the signer public key 407.

[0093] Data field 405 includes slot number 410, which indicates the index of record 201 within configuration memory 115. Data field 405 also includes another copy of metadata encapsulation key 411 (in addition to Figure 2 The data field 405 is encrypted using the Authorized Device Slot Key (ADSK) 412, which is a 16-byte pseudo-random value stored in the configuration memory 115 and is used to encrypt the data in the Authorized Device Certificate so that only the issuing DSD 100 can recover the information.

[0094] Unlocking data storage devices

[0095] return Figure 3 If the authorizing device 111 wishes to unlock the DSD 100, the authorizing device 111 sends 303 to the access controller 102 a certificate 400 including the encrypted metadata wrapping key (MWK) 213 / 411. The certificate 400 also includes a slot number 410, which is an index of the record 201 in the configuration memory 115.

[0096] The access controller 102 decrypts 304 the data field 405 using the authorized device slot key stored in the configuration memory 115 and extracts the slot number and the metadata encapsulation key. The access controller 102 then queries the configuration memory 115 to read 305 the appropriate record 201 from the configuration memory 115 and decrypts 306 the authorized device metadata 205 using the metadata encapsulation key. This generates a temporary public key 211, which may also be referred to as an identifier of the authorized device, which uniquely identifies the authorized device because the temporary public key 211 is cryptographically associated with an unlocking private key stored only on the authorized device 111. The access controller 102 may perform additional checks 307, such as verifying that the transport public key 209 included in the authorized device metadata 205 matches the transport public key 404 provided in the certificate 400. In addition, the access controller 102 verifies the role 401 against a set of valid values ​​and associates the role with the connection. This means that the access controller 102 knows the current role ("user" or "administrator") for the duration of the connection. For example, the access controller 102 stores a parameter value indicating the role 401 provided in the certificate on a volatile memory. If any of the foregoing checks fail, the authorized device is considered revoked and an error is issued to that effect. Otherwise, the connection attempt is successful and the access controller 102 sends 308 a connection confirmation message to the authorized device 111.

[0097] At this stage, the authorization device 111 is connected and the unlocking process begins 319 by the authorization device 111 sending 320 an unlock request to the access controller 102. The unlock request includes an unlock public key associated with a private key stored on the secure hardware module of the authorization device. The access controller 102 matches 321 the received unlock public key with the unlock public key 212 stored in the authorization device metadata record 205. Next, the access controller 102 generates 322 a new blind value (also called an unlock blind key (UBK)), which is essentially a temporary private scalar and is randomly generated.

[0098] The access controller 102 then generates a challenge based on the identifier of the authorized device (e.g., the temporary public key 211) multiplied by the unlocking blind key (UBK). More specifically, the access controller 102 multiplies 323 the temporary public key 211 by the unlocking blind key, returning the complete X and Y coordinates of the result, noting that this operation is performed on an elliptic curve. The access controller 102 then sends 324 the X and Y coordinates to the authorized device 111 as a challenge. Note here that the challenge is based on the identifier of the authorized device 111 because the temporary public key is a factor of the multiplication that derives the challenge. Note also that for each unlock request (i.e., 320), a different unlocking blind key is generated to avoid man-in-the-middle attacks.

[0099] In addition, the access controller 102 calculates 325 the inverse of the unlocking blinding key (UBK -1 ). The access controller 102 may calculate the inverse of the unlocking blind key while waiting for a response from the authorization device 111.

[0100] The authorization device 111 calculates a response to the challenge by multiplying 326 the challenge by an unlock private key that is stored in a secure hardware module of the authorization device and corresponds to the unlock public key 212 stored on the configuration memory 115. This may involve the execution of a cryptographic primitive that may be executed entirely within a secure hardware module within the authorization device 111. The authorization device 111 then sends the result back in a response message 327. The access controller 102 multiplies 328 the returned result by the inverse of the unlock blinding key to calculate a temporary unlock secret (EUS) 223.

[0101] In mathematical notation, P represents the temporary public key, and k represents the Figure 3 The access controller 102 calculates 323 the product k*P and sends it 324 to the authorization device 111. The authorization device 111 multiplies 326 the challenge with the unlocking private key j to calculate j*k*P and returns 327 the result to the access controller 102. The access controller 102 compares the response to the inverse k of the unlocking blind key. -1 Multiply 238 to calculate

[0102] k -1 *j*k*P,

[0103] Due to the commutative property of elliptic curves, it is equal to j*P (i.e., k -1 *j*k*P=k*k -1 *j*P=j*P).

[0104] The access controller 102 then decrypts 329 the user key 221 using j*P as a temporary unlocking secret (i.e., key). That is, the access controller 102 uses the temporary unlocking secret to decrypt the user key 221 stored on the DSD 100, which was encrypted using the temporary unlocking secret. More specifically, the access controller 102 decrypts 329 the user key, which then decrypts 330 the "user drive key", which is then ultimately sent 331 to the encryption engine 106 via a TCG command. That is, the user drive key can be generated by the access controller 102 using a key derivation function based on the user key. The user drive key is a TCG credential used to unlock the DSD 100, and can be equivalent to the "encryption key" described herein. In the case of Opal, this is the User2 credential.

[0105] Note that a temporary unlock secret is generated during the re-registration process by deriving a symmetric key from the results of an Elliptic Curve Diffie-Hellman process using an unlock private key and an unlock public key 212 stored on the authorized device 111. The resulting key is used to encrypt the user key 221, but is not stored in the DSD 100. Instead, the key is regenerated each time an authorized device requests unlocking of the DSD 100, as described above.

[0106] In another example, in the above formula, the unlock private key j can be replaced by the product of the unlock private key and a value derived from the pass code. The unlock private key will still be stored in the secure hardware module of the authorized device, but the unlock private key alone will not be able to decrypt the user content data stored on the DSD 100. Instead, the user needs to enter the pass code to calculate the response to the challenge and send 327 the response. This will simply replace j with the product of the pass code value and j above. The DSD will ignore this change because the temporary unlock secret 223 will be generated in the same manner as above from the perspective of the access controller 102.

[0107] Registration and Re-registration

[0108] Please note that Figure 2 The data record 201 shown is shown after the authorization device 111 has completed the re-registration process and is allowed to decrypt the encrypted user content data. Again, there are three steps in general: First, the manager device 110 registers the user device 111 once, making it one of the multiple authorization devices. Second, when connecting to the access controller 102 for the first time, the authorization device 111 re-registers once to complete the generation of the keys involved. Third, the authorization device 111 subsequently connects to the access controller 102 to unlock the DSD 100. This third step can occur multiple times.

[0109] During an (initial) registration step initiated by the manager device 110, the access controller 102 receives from the manager device 110 a public key corresponding to a private key stored on the user device 111. In response, the access controller 102 creates authorization data similar to Figure 2 1, except that the unlock public key 212 field holds the transmission public key 209 (as received from the manager device 110) since the unlock public key has not yet been generated. The access controller 102 generates a pre-authorization key 202, which is essentially an index used to locate the record 201. The pre-authorization key is generated by a key generation function using the x-coordinate of the received transmission public key 209 and a salt value. The salt value may be an authorized device slot key, which may be a 16-byte pseudo-random value generated during the "take ownership" process, stored on the configuration memory 115, and not shared with the authorized device. In this way, the salt may be different after each "factory reset", such as each time a manager device takes ownership of the DSD 100.

[0110] Creating the authorization data stored in record 201 also includes generating a metadata encapsulation key 222, such as by generating a 16-byte pseudo-random value. Access controller 102 stores the metadata encapsulation key in field 222. In addition, access controller 102 generates a temporary unlocking secret 223 and encrypts role 220 ("user" or "manager"), user key 221, and new metadata encapsulation key 222 using temporary unlocking secret 223. Access controller 102 then generates a temporary public key 211 from temporary unlocking secret 223 and discards temporary unlocking secret 223.

[0111] Recall that during the (initial) registration step initiated by the manager device 110, the access controller 102 creates a Figure 2 Authorization data in data record 201. Figure 2 In contrast, the authorized device metadata 205 is not encrypted by a new metadata encapsulation key, but by a pre-authorized metadata encapsulation key, because the actual metadata encapsulation key 222 is not yet available to the authorized device 111. The pre-authorized metadata encapsulation key may be the same as the pre-authorized key 202 at this stage or generated separately. It should be noted that the pre-authorized metadata encapsulation key that now encrypts the authorized device metadata 205 may only be generated by the access controller 102, and not provided by the authorized device 111, because the authorized device 111 does not have access to the authorized device slot key used to generate the pre-authorized metadata encapsulation key.

[0112] Thus, in response to the authorization device 111 first connecting with the access controller 102, the authorization device 111 sends its transport public key to the access controller 102. The access controller 102 uses the transport public key and the stored authorization device slot key to generate the pre-authorization key 202. The access controller 102 may then search the configuration memory 115 for the pre-authorization key 202 to retrieve the record 201. The access controller 102 may also use the pre-authorization key as a pre-authorization metadata encapsulation key to decrypt the authorization device metadata 205.

[0113] As described above, the access controller 102 generates a challenge using the temporary public key 211 and the unlock blind key. The access controller 102 then creates the temporary unlock secret 223 from the response. Note that only the authorized device 111 with the private key corresponding to the transmission public key 209 can create a valid response. This means that even if an attacker disassembles the configuration memory 115 and reads the authorized device slot key to generate the pre-authorization metadata encapsulation key to decrypt the temporary public key 211, the attacker will still not be able to generate the temporary unlock secret 223.

[0114] The access controller 102 verifies the response by checking that the response acts as a temporary unlocking secret 223, and in response, updates the authorization data in the record 201. More specifically, the access controller 102 checks whether the field 212 for the unlocking public key is the same as the transmission public key 209. In response to the two being the same (as described above), the access controller 102 requests a new unlocking public key from the authorization device 111 and stores the returned key as the unlocking public key 212.

[0115] The access controller further decrypts the metadata encapsulation key 222 generated during registration by the manager device 110. At this stage, the access controller 102 may regenerate the temporary unlocking secret 223, the encryption role 220, the user key 221, and the metadata encapsulation key 222, regenerate and store the temporary public key 211, and discard the temporary unlocking secret 223. Finally, the access controller encrypts the authorized device metadata 205 using the metadata encapsulation key 222, and overwrites the pre-authorization key 202 with a random value so that the configuration memory 115 cannot be distinguished from random data even when holding the transmission public key and / or the unlocking public key. This ends the update and registration process of the authorization data stored in the record 201. Therefore, the authorized device 111, as one of the multiple authorized devices, is now allowed to decrypt the encrypted user content data through the above-mentioned unlocking step.

[0116] The above process involving creation and updating of authorization data enables multiple authorized devices to register using only their public keys during a first step of registration by manager device 110. In this way, there is no need to share secret information that could be intercepted and used to maliciously unlock the user's other devices.

[0117] Multiple roles

[0118] return Figure 2 , the configuration memory 115 stores a plurality of entries, of which only two are shown (a first entry 201 and a second entry 250). In most cases, there is one entry for each registered device. Each "registered" device may be a manager device 110 or an authorized device 111, 117, 118, 120, 121. Additional entries may exist, such as for recovery keys (not shown).

[0119] The first entry 201 is associated with the authorizing device 111 as explained in detail above. Note again that the first entry stores a user key 221 encrypted by a temporary unlocking secret 223, which can be calculated from the response to the challenge using the temporary public key ECC-Pub (EUK) 211.

[0120] The second entry 250 is associated with the manager device 110. Most of the fields in the second entry 250 have the same functions as in the first entry 201 and are described above. In summary, the pre-authorization key 252 enables the second entry 250 to be located at the first connection of the manager device 110 to the DSD 100, noting that the manager device 110 may have been registered by another manager device that originally performed the acquisition ownership process. This registration is performed in the same manner as the registration of the authorized device described above (including re-registration and using certificates to provide entry indexes and metadata encapsulation keys). Similarly, a copy of the metadata encapsulation key 253 and the pre-authorized metadata encapsulation key 264 are stored encrypted by the authorized device metadata key to enable the manager to access the authorized device metadata 255 encrypted by the metadata encapsulation key 263. The metadata encapsulation key 263 is provided by the manager device 110 in the certificate to decrypt the authorized device metadata 255 including the device type 256 and the role 257. The role 257 is now different from the role 207 because the role 257 holds a value indicating the administrator role, while the role 207 holds a value indicating the user role. It should be noted that the metadata encapsulation key 203 / 213 / 222 of the first entry 201 is different from the metadata encapsulation key 253 / 263 / 272 of the second entry 250 .

[0121] Likewise, similar to the first entry 201, the authorized device metadata 255 includes the name 258 of the manager device 110, the transport public key 259, the unlock key metadata 260, the temporary public key 261, and the unlock public key 262. These functions are similar to their corresponding functions in the first entry 201 and are described above. The manager device 110 also stores the transport private key and the unlock private key on the secure hardware module. In addition, the access controller 102 generates a challenge based on the temporary public key 261 and calculates a temporary unlock secret 273 based on the response from the manager device 110, which decrypts the second copy of the role 270 and the second copy of the metadata encapsulation key 272. Compared to the first entry 201 where the user key 221 was decrypted, the temporary unlock secret 273 now decrypts the manager key 271 that provides manager access rights.

[0122] In some examples, the user key 221 can be derived directly from the manager key 271, which means that the manager key is the only secret information required to calculate the user key. The derivation can be one-way, which means that the manager key cannot be derived from the user key. The derivation can be based on a hash function, such as a hash-based message authentication code (HMAC) according to the Internet Engineering Task Force (IETF) request for comment (RFC) 5869, using the Secure Hash Algorithm 2 (SHA-2) with 512 bits (see also National Institute of Standards and Technology Special Publication (SP) 800-56C). It is noted that the manager key is the same for all manager device entries, and therefore, the user key is also the same for all authorized device entries.

[0123] Having an exportable user key also means that once the manager key 271 is available, the user key can always be calculated. Therefore, in response to the manager device 110 providing a correct response to the challenge, the access controller 102 can use the user key derived from the manager key 271 to decrypt the user content data, and the manager key is decrypted based on the response. Therefore, the manager device is said to have manager access rights, which include access rights to user content data and access rights to authorization data stored on the configuration memory 115. Therefore, the manager device 110 can request a list of registered devices that can be provided by the access controller 102. Therefore, the manager device 110 can store the list locally on the manager device 110 and display the list on the graphical user interface. The process of retrieving all entries of registered devices can be supported by a bitmap data object, which includes one bit for each possible data entry, such as 256 bits for 256 possible registered devices. The access controller 102 sets the bit to "1" in response to writing one of the multiple entries. In this way, the access controller 102 can determine which entries are valid and do not attempt to decrypt invalid entries.

[0124] In contrast to manager device 110, authorization device 111 does not have access to manager key 271, but only has access to user key 221, which does not enable decryption of metadata for other devices. Thus, it is said that reading of authorization data associated with other registered devices is limited to the authorization device (which does not have access to manager key 271).

[0125] It should be noted here that each entry 201 / 250 and each additional entry not shown includes metadata encrypted by a different metadata encapsulation key. Therefore, in response to providing manager access rights, the access controller 102 determines a separate metadata encapsulation key for each entry. More specifically, where the manager key 271 is available, the access controller 102 calculates the authorized device metadata key 254 (which is the same for all entries) and uses this key to decrypt each entry-specific metadata encapsulation key 203 / 253, which in turn enables the access controller 102 to decrypt each authorized device metadata 255. It should also be noted that the manager access rights do not allow the user key 221 to be decrypted from the authorized device entry because the calculation of the temporary unlocking secret 223 requires the unlocking secret key to be retained in the memory of each authorized device. However, the user key 221 is derivable from the manager key 271, so there is no benefit for the manager device 110 to decrypt the user key 221 from the authorized device entry 201.

[0126] In summary, entries 201 and 250 store user keys 221 or manager keys 271, which enable an access controller to selectively provide user access rights or manager access rights to a plurality of registered devices.

[0127] Methods used to provide access

[0128] Figure 5A method 500 for providing access rights to a data storage device is shown according to one embodiment. The method begins with the access controller 102 storing 501 a plurality of entries 201 / 250 associated with a plurality of corresponding registered devices 110 / 111 on the configuration memory 115. The plurality of entries 201 / 250 include authorization data 201 / 250 indicating an encryption key 221 / 271 that selectively provides user access rights or manager access rights for each of the plurality of registered devices 110 / 111. The access controller 102 connects 502 to a registered device in the plurality of registered devices 110 / 111 and selects 503 one of the plurality of entries associated with the connected registered device. The access controller 102 then enables 504 the use of one of the encryption keys of the selected one of the plurality of entries to provide user access rights or manager access rights for one of the plurality of registered devices.

[0129] Registering a Data Storage Device

[0130] Data port 103 registers as a block data storage device with host computer system 104. For example, a Universal Serial Bus (USB) device provides information in the form of a USB device descriptor. The USB device descriptor contains relevant information about the device. Therefore, in an embodiment where the data storage device is connected to the host computer system via a USB connection, the data storage device registers as a block data storage device with the host computer system by configuring its USB device descriptor to indicate that the data storage device is a block data storage device.

[0131] The USB device descriptor provides structured information about the USB device, such as the device class, supported protocols, device type, manufacturer, and other configuration parameters. The operating system of the host computer can obtain the USB device descriptor of the data storage device by sending various standard control requests (e.g., GET_DESCRIPTOR requests) to the data storage device. In response to receiving these requests, the data storage device provides the USB_DEVICE_DESCRIPTOR to the host computer system, thereby registering the data storage device as a block data storage device to the host computer system. The host computer interprets the USB_DEVICE_DESCRIPTOR to determine the configuration and capabilities of the data storage device. The host computer system can then store information about the data storage device in a register of the operating system of the host computer system.

[0132] It will be appreciated by those skilled in the art that many variations and / or modifications may be made to the above-described embodiments without departing from the broad general scope of the present disclosure. The embodiments of the present invention are therefore to be considered in all aspects as illustrative and not restrictive.

Claims

1. A data storage device, comprising: A data path, the data path comprising: a data port configured to transfer data between a host computer system and the data storage device; a non-volatile storage medium configured to store encrypted user content data; and an encryption engine connected between the data port and the storage medium and configured to decrypt the encrypted user content data stored on the storage medium using a content data encryption key in response to a request from the host computer system; and An access controller, the access controller being configured to: A plurality of authorization data entries are stored in a data repository, wherein: Each authorization data entry in the plurality of authorization data entries is associated with a registered device in the plurality of registered devices; and the plurality of authorization data entries including authorization data indicating an encryption key that selectively provides user access rights or administrator access rights for each of the plurality of registered devices; communicating with a registration requesting device among the plurality of registration devices; selecting the authorization data entry associated with the device requesting registration; determining the content data encryption key using the authorization data entry associated with the requesting registration device; and The requesting registration device is selectively provided with user access rights or administrator access rights to unlock the encrypted user content data for the host computer system.

2. The data storage device according to claim 1, wherein the user access rights: enabling decryption of said encrypted user content data; and Restricts reading of authorization data associated with other registered devices.

3. The data storage device according to claim 1, wherein the manager access rights: enabling decryption of said encrypted user content data; and Enables reading of authorization data associated with other registered devices.

4. A data storage device according to claim 1, wherein each authorization data entry comprises authorization data indicating: A user key to provide user access to said content data encryption key; or A manager key to provide manager access rights to the plurality of authorization data entries. 5 . The data storage device of claim 4 , wherein each authorization data entry comprises a key field configured to store authorization data indicative of only one of the user key and the manager key.

6. The data storage device of claim 4, wherein the user key is derivable from the manager key via a one-way function.

7. The data storage device according to claim 6, wherein: The manager key is configured to enable reading of authorization data associated with other registered devices; and The user key, derivable from the manager key, is configured to enable decryption of the encrypted user content data.

8. The data storage device of claim 4, wherein the user key is the same for a plurality of authorization data entries providing user access rights.

9. The data storage device of claim 4, wherein the manager key is the same for a plurality of authorization data entries providing manager access rights.

10. The data storage device of claim 1, wherein: The authorization data of each of the plurality of authorization data entries is encrypted based on a private key stored on an associated registration device of the plurality of registration devices; and The associated registered device is associated with the authorization data entry.

11. The data storage device of claim 10, wherein the private key is different for each registered device of the plurality of registered devices.

12. The data storage device of claim 11, wherein: Each authorized data entry providing user access rights includes encrypted metadata encrypted by a metadata encryption key; The metadata encryption key is based on the private key stored on each of the plurality of registered devices, and the metadata encryption key is different for each authorization data entry; and The metadata encryption key is stored in an authorization data entry encrypted based on a manager key to provide access rights to the encrypted metadata in response to obtaining the manager key.

13. The data storage device of claim 1 , wherein the access controller is further configured to: generating a challenge to the requesting registration device among the plurality of registration devices; sending the challenge to the requesting registration device among the plurality of registration devices via a communication channel different from the data path; receiving a response to the challenge from the requesting registration device among the plurality of registration devices via the communication channel; and decrypting the authorization data based at least in part on the response to obtain an access key, the access key being one of: A manager key that provides manager access, and A user key that provides user access permissions.

14. The data storage device of claim 13, wherein the challenge is based on the authorization data.

15. The data storage device of claim 13, wherein the challenge is based on a public key of the requesting registration device of the plurality of registration devices.

16. The data storage device of claim 1, wherein the access controller is further configured to encrypt the encryption key to generate the authorization data.

17. The data storage device of claim 16, wherein the access controller is further configured to perform the following steps for each authorization data entry of the plurality of authorization data entries: Generate a temporary private key and a corresponding temporary public key; encrypting the content data encryption key based on the temporary private key and an unlocking public key corresponding to an unlocking private key stored on a corresponding registered device; discarding the temporary private key; and The temporary public key and the unlocking public key are stored.

18. The data storage device of claim 1, wherein the data storage device is configured to register with the host computer system as a block data storage device.

19. A method for providing access to a data storage device from a host computer system, the method comprising: A plurality of authorization data entries are stored on a data repository in the data storage device, wherein: Each authorization data entry in the plurality of authorization data entries is associated with a registered device in the plurality of registered devices; and the plurality of authorization data entries including authorization data indicating an encryption key that selectively provides user access rights or administrator access rights for each of the plurality of registered devices; communicating with a registration requesting device among the plurality of registration devices; selecting an authorization data entry associated with the device requesting registration; determining a content data encryption key using the authorization data entry associated with the requesting registration device; and The requesting registration device is selectively provided with user access rights or administrator access rights to unlock the encrypted user content data from the data storage device to the host computer system.

20. A data storage device comprising: means for storing a plurality of authorization data entries on a data repository in said data storage device, wherein: Each authorization data entry in the plurality of authorization data entries is associated with a registered device in the plurality of registered devices; and the plurality of authorization data entries including authorization data indicating an encryption key that selectively provides user access rights or administrator access rights for each of the plurality of registered devices; means for communicating with a requesting registration device among the plurality of registration devices; means for selecting an authorization data entry associated with the device requesting registration; means for determining a content data encryption key using said authorization data entry associated with said requesting registration device; and Means for selectively providing the requesting registration device with user access rights or administrator access rights to unlock encrypted user content data from the data storage device to a host computer system.

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