A digital asset protection method using sram puf characteristics
By adopting the integrated SRAMPUF+ECDSA signature architecture, the entropy source of the initial state of SRAM power-on is extracted using FPGA chip, and a stable PUF key is dynamically generated. Combined with public key hashing and AES-256-GCM encryption, the key storage risk and high energy consumption problem of traditional solutions are solved, and low-power and secure digital asset management is realized.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- GUANGDONG LVSUAN TECH CO LTD
- Filing Date
- 2026-05-27
- Publication Date
- 2026-07-10
AI Technical Summary
Traditional authentication and signature schemes have several drawbacks when implementing device authentication and digital signature functions. Key storage risks exist, biometric technology is difficult to meet the requirements of high-precision signature verification, and cryptographic methods face challenges in implementation complexity and resistance to quantum computing, making it difficult to balance physical security, algorithm security, and implementation efficiency.
It adopts an integrated SRAMPUF+ECDSA signature architecture, uses an FPGA chip to extract the entropy source of the SRAM initial power-on state, dynamically generates a stable PUF key, and combines public key hashing, AES-256-GCM encryption and elliptic curve digital signature to achieve device authentication and data encryption through NFC touch wake-up and Bluetooth transmission.
It improves the security of key storage, reduces hardware costs and power consumption, prevents replay attacks, enhances the network configuration and user experience of IoT devices, and provides a secure, portable, and low-power digital asset management solution.
Smart Images
Figure CN122372223A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of information security technology, and in particular relates to a method for protecting digital assets using the characteristics of SRAMPUF. Background Technology
[0002] The convergence of technologies such as blockchain and biometrics has driven the development of signature authentication, leading to its widespread application in finance, government affairs, and healthcare. However, with the deepening of digital transformation, security threats such as data tampering and identity forgery are becoming increasingly prominent. Traditional authentication methods (such as passwords) are vulnerable to attacks and cannot meet the needs of high-security scenarios. Electronic signatures rely on encryption technology to ensure data integrity, non-repudiation, and identity authenticity, becoming a core guarantee for secure communication and transactions. Especially in areas such as financial payments, electronic contracts, and the Internet of Things, signature authentication needs to resist risks such as man-in-the-middle attacks and replay attacks.
[0003] Current mainstream authentication and signature schemes mainly adopt three technical approaches: 1. Securely stored keys: Signature functionality is achieved by storing a pre-set key in a protected non-volatile memory. Although this method employs measures such as physical isolation and encrypted storage, it still inherently carries the risk of key extraction and cannot resolve the security vulnerabilities of key injection in the supply chain. 2. Biometric recognition: Device fingerprints are generated using the physical features of the device, but the feature extraction process is easily affected by environmental noise, making it difficult to guarantee the stability and consistency of signature verification, and there is a risk of feature modeling attacks. 3. Based on traditional asymmetric cryptography: Although it can provide mathematically provable security, it requires a complex key management mechanism, which is difficult to implement in resource-constrained devices, and it also faces long-term security challenges brought about by quantum computing.
[0004] In summary, traditional methods have significant shortcomings in implementing device authentication and digital signature functions: storage-based solutions cannot fundamentally address the security risks associated with persistent key storage; biometric technologies struggle to meet the demands of high-precision signature verification; and cryptographic methods suffer from both implementation complexity and quantum resistance limitations. Especially in scenarios requiring simultaneous device authentication and digital signature functionality, traditional solutions often fall short of balancing physical security, algorithmic security, and implementation efficiency. A novel security mechanism based on the physical non-cloning property is still needed to build a more reliable authentication and signature system.
[0005] PUF (Physical Unclonable Function) is a security technology based on the inherent randomness of hardware, capable of generating a unique digital fingerprint for a device. PUF technology eliminates the need for key storage, offers resistance to physical attacks, protects NFT digital assets, provides edge computing security, and offers anti-counterfeiting and traceability features, providing uncopyable digital identity credentials for physical goods.
[0006] SRAMPUF has become one of the most widely used PUF technologies due to its advantages such as fast response speed, high stability, and compatibility with standard CMOS processes, making it particularly suitable for IoT devices requiring rapid authentication. However, this technology still has the following drawbacks: SRAM leakage current reaches 1nA / bit (40nm process) during standby, which significantly affects the battery life of button battery devices (such as smart tags); SRAM has a large area overhead, with a traditional 6TSRAM cell requiring 140F. 2 Area; using SRAM chips alone to extract the entropy source of the initial state of SRAM upon power-on is at risk of being attacked by physical probes. Summary of the Invention
[0007] In view of the shortcomings of the prior art, the purpose of this invention is to provide a digital asset protection method that utilizes the characteristics of SRAMPUF to dynamically generate stable PUF keys and improve the security of key storage.
[0008] This invention proposes a digital asset protection method utilizing SRAMPUF features, comprising: S1. Configure a unique device identifier (DID) for the SRAMPUF device. The SRAMPUF device is implemented using an FPGA chip, and the unique ID number of the FPGA chip is concatenated by a public key hash as the unique device identifier (DID). S2, The device unique identifier DID is pre-set in the NFC tag. When the mobile terminal touches the SRAMPUF device with NFC, it supports NFC touch wake-up and automatically launches the matching APP. The SRAMPUF device is identified according to the pre-set device unique identifier DID, and the connection between the matching APP on the mobile terminal and the SRAMPUF device is started. S3, establish an encrypted data transmission link between the APP and the SRAMPUF device. In each session, the APP and the SRAMPUF device use a dynamically and randomly generated temporary session key to encrypt the transmitted data. S4, the server uses a challenge-response mechanism to authenticate SRAMPUF devices, including: The server sends a random challenge to the mobile terminal APP, and the mobile terminal APP sends the random challenge to the SRAMPUF device through a data encryption transmission link. The SRAMPUF device generates a PUF response based on the random value input in the random challenge, and signs the challenge using the Elliptic Curve Digital Signature (ECDSA) algorithm to generate an ECDSA signature (R, Sig). The server verifies the ECDSA signature (R, Sig) using a pre-registered public key. The ECDSA signature (R, Sig) is generated by the PUF device signing the hash value of the PUF response using the key PUF_Key. S5. Perform asset access and asset encryption based on the key PUF_Key, the hash value of the PUF response, and the asset access credential.
[0009] Furthermore, an encrypted data transmission link is established between the APP and the SRAMPUF device, including: The app sends the RSA public key to the SRAMPUF device with a digital signature; The SRAMPUF device verifies the signature and extracts the RSA public key, generates a random temporary session key and its hash value, encrypts the temporary session key and its hash value using the RSA public key, and then sends the encrypted data to the APP. The app uses the private key corresponding to the RSA public key to decrypt the encrypted data. After verification, the encrypted data transmission link is established and encrypted transmission is started.
[0010] Furthermore, in S3, the data link between the APP and the SRAMPUF device is encrypted using the AES-256-GCM algorithm, and the SRAMPUF device randomly generates a temporary session key.
[0011] Furthermore, in S4, the server uses the pre-registered public key to verify the ECDSA signature (R, Sig) to determine whether the signature is a valid signature of the hash value Hash(C) of the random challenge C. If the verification is successful, the login authentication is successful, and the authentication result is returned to the APP.
[0012] Furthermore, in S4, the FPGA chip extracts the entropy source from the initial power-on state of the SRAM and dynamically generates a unique and stable PUF key PUF_Key, including: When the FPGA is powered on, the SRAM is not initialized and each memory cell is in a random state. The initial value of the SRAM is read. Read the initial bit sequence of the SRAM, extract the original entropy, ensure that the key is reliably extracted and reconstructed from the physical randomness of the SRAM, and correct the deviation during reading using error correction codes; Each time power is applied, the SRAM entropy source is re-extracted to dynamically generate a unique and stable PUF key PUF_Key for the device. After use, the intermediate data in the SRAM is cleared to ensure that no key remains.
[0013] Furthermore, in S5, the asset access includes: After receiving a user's asset access request, the APP challenges the SRAMPUF device, which returns an ECDSA signature (R, Sig). The ECDSA signature (R, Sig) is generated by the PUF device signing the hash value of the PUF response using the key PUF_Key. The APP calculates Key'=Hash(C||R) based on the random challenge C and the component R in the signature, and sends it to the encryption engine. The encryption engine uses the key Key' to decrypt the asset in the asset library and returns the decrypted plaintext asset to the user.
[0014] Furthermore, in S5, the asset encryption includes: after the APP receives the user's asset access request, it challenges the SRAMPUF device, and the SRAMPUF device returns an ECDSA signature (R, Sig); the ECDSA signature (R, Sig) is generated by the PUF device signing the hash value of the PUF response using the key PUF_Key; The APP calculates the key Key'=Hash(C||R) based on the random challenge C and the component R in the ECDSA signature, and sends it to the encryption engine. The encryption engine uses the key Key' to encrypt the assets given in the asset library.
[0015] Furthermore, the dynamic digital signature generated by the SRAMPUF device is transmitted between the mobile terminal NFC tag and the SRAMPUF device via a Bluetooth chip.
[0016] Furthermore, a two-stage power supply method is adopted, in which the Bluetooth chip controls the power supply of the FPGA chip. When authentication is initiated or when the device is woken up, the Bluetooth chip supplies power to the subsequent circuit. After the FPGA chip returns the authentication data, it immediately cuts off the power supply to the subsequent circuit.
[0017] Furthermore, both the NFC data of the NFC tag and the Bluetooth name of the Bluetooth chip are equipped with the device unique identifier (DID) to enable the mobile terminal to match the corresponding SRAMPUF device during the touch process.
[0018] The beneficial effects of this invention are as follows: To address the security authentication and low power consumption requirements of IoT terminal devices, this device implements a hardware-level security solution based on SRAMPUF.
[0019] 1. Adopting an integrated SRAMPUF+ECDSA signature architecture, the entropy source of the SRAM initial power-on state is extracted on the FPGA chip, and a stable PUF key is dynamically generated, which fundamentally solves the key storage risk of traditional security solutions.
[0020] 2. The ECDSA signature algorithm (BK_ECC_CURVE_NIST_P521) is implemented by reusing the same FPGA hardware resources. Compared with the external SRAMPUF method, this optimizes hardware space and reduces hardware costs, while also reducing power consumption. Moreover, using built-in SRAM prevents the direct acquisition of chip startup information using physical probes, thus providing higher security.
[0021] 3. Use public key hash (SHA3-256) to construct the unique ID number of the FPGA chip as the device's unique identifier DID, ensuring the irreversibility and uniqueness of the generated identifier.
[0022] 4. The data link uses AES-256-GCM encryption for transmission. Each signature uses a dynamically randomly generated session key to prevent replay attacks and achieve forward security.
[0023] 5. By pre-setting the device's digital identity (DID) in the NFC tag, the entire process of launching the App upon touch and automatically completing device connection is optimized, significantly improving the network configuration and user experience of IoT devices.
[0024] 6. By transmitting the dynamic digital signature generated by the PUF device through Bluetooth Low Energy (BLE), the device identity is ensured to be unforgeable, fundamentally solving the problems of key storage risks, high energy consumption and inconvenient deployment in traditional security solutions. This provides a secure, portable and low-power digital asset management solution for IoT edge devices.
[0025] 7. The hardware circuit corresponding to this invention adopts a two-stage power supply method. The Bluetooth chip controls the power supply of the FPGA chip and only supplies power to the subsequent circuit when an authentication or signature operation is initiated. After the FPGA chip returns the authentication data, it immediately cuts off the power supply to the subsequent circuit, which reduces the operating power consumption and standby power consumption of the subsequent circuit. The Bluetooth operating power consumption is 5mA, and the FPGA chip operating power consumption is 15mA. Using this method, the operating power consumption is reduced by 75%. Since there is no need to consider the standby power consumption of the FPGA, a higher performance and larger scale FPGA chip can be selected during the design, which expands the upper limit of computing power and functional integration.
[0026] 8. Supports NFC touch wake-up and automatic launch of the accompanying app, enabling seamless authentication and interaction. Users simply need to touch their phone to their wallet to complete the wake-up process, identity authentication, connection, and binding. The wake-up method utilizes both NFC and button input. NFC data and Bluetooth names contain device identifiers, allowing mobile devices to quickly pair with each other, greatly simplifying the user experience. Furthermore, the app launch field in the NFC NDEF data is configurable, allowing users to adapt their apps to their needs, offering enterprise-level deployment flexibility.
[0027] 9. The design utilizes a minimal form factor based on e-ink display, making it easy to integrate into badges or other creative products. Users can change the image on the wallet's e-ink display via an app to create a personalized style. The e-ink display's ability to continue displaying even when power is off enables ultra-low power consumption. Attached Figure Description
[0028] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts. It is obvious that the drawings described below are merely some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings.
[0029] Figure 1 This is a flowchart illustrating a digital asset protection method utilizing SRAMPUF features according to an embodiment of the present invention; Figure 2 This is a flowchart illustrating the authentication process of the login management mechanism according to an embodiment of the present invention. Figure 3 This is a flowchart illustrating asset access according to an embodiment of the present invention; Figure 4 A flowchart illustrating asset encryption in an embodiment of the present invention; Figure 5 This is a flowchart of key exchange and authentication according to an embodiment of the present invention; Figure 6 This is a hardware architecture diagram of a digital asset protection method utilizing SRAMPUF features according to an embodiment of the present invention. Detailed Implementation
[0030] To enable those skilled in the art to better understand the technical solutions in the embodiments of the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. It should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.
[0031] Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concepts disclosed in this invention.
[0032] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The terms "installed," "connected," and "linked" should be interpreted broadly; for example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.
[0033] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples of methods and systems consistent with some aspects of the invention as detailed in the appended claims.
[0034] This invention employs an integrated SRAMPUF+ECDSA signature architecture. It extracts the entropy source from the initial power-on state of the SRAM on the FPGA chip, dynamically generates a stable PUF key, and reuses the same FPGA hardware resources to implement the ECDSA signature algorithm. This optimizes hardware space, reduces hardware costs, and lowers operating power consumption. The FPGA reuse scheme used in this invention time-division multiplexes SRAM blocks, first extracting the PUF key and then switching to ECDSA signature mode, sharing the computing unit and storage architecture.
[0035] like Figure 1 As shown, this invention proposes a digital asset protection method utilizing SRAMPUF features, comprising: S1. Configure the device unique identifier DID for the SRAMPUF device. The SRAMPUF device is implemented using an FPGA chip, and the unique ID number of the FPGA chip is concatenated by public key hash as the device unique identifier DID.
[0036] In this invention, the SRAMPUF device extracts the entropy source of the initial power-on state of the SRAM on the FPGA chip and dynamically generates a stable PUF key.
[0037] This invention uses the SHA3-256 public-key hash algorithm to concatenate the unique ID number of the FPGA chip as the Device Unique Identifier (DID), ensuring the irreversibility and uniqueness of the generated identifier. The Device Unique Identifier (DID), as the unique identifier of the FPGA chip, can be used for subsequent matching and identification.
[0038] S2: The device unique identifier (DID) is pre-set in the NFC tag. When the mobile terminal touches the SRAMPUF device with NFC, it supports NFC touch wake-up and automatically launches the accompanying APP. The SRAMPUF device is identified according to the pre-set device unique identifier (DID), and the connection between the accompanying APP on the mobile terminal and the SRAMPUF device is initiated.
[0039] Specifically, by pre-setting the Device Identifier (DID), which serves as the device's digital identity, in the NFC tag, the entire process of launching the App upon touch and automatically completing the device connection can be optimized, significantly improving the network configuration and user experience of IoT devices.
[0040] When a mobile device touches the SRAMPUF device using NFC, it identifies the DID (Distributed ID) and then the SRAMPUF device associated with that DID. This initiates the connection between the app and the SRAMPUF device, and begins the key exchange and authentication process. This invention supports NFC touch (e.g., tap-to-wake) to wake up and automatically launch the accompanying app, enabling seamless authentication and interaction. For example, users only need to touch their phone to their wallet to complete the wake-up process, identity authentication, connection, and binding.
[0041] It should be noted that, in addition to the NFC wake-up method mentioned above, this invention also supports the button wake-up method.
[0042] S3 establishes an encrypted data transmission link between the APP and the SRAMPUF device. During each session, the APP and SRAMPUF device use a dynamically and randomly generated temporary session key to encrypt the transmitted data. The temporary session key encrypts the transmitted data between the APP and the device, preventing eavesdropping and tampering.
[0043] like Figure 5 As shown, the process for establishing an encrypted data transmission link between the APP and the SRAMPUF device is as follows: (1) The mobile terminal APP sends the RSA public key to the SRAMPUF device through digital signature.
[0044] RSA is an asymmetric encryption algorithm used for secure data transmission. RSA uses a pair of keys: a public key (publicly available, used for encryption) and a private key (secretly kept, used for decryption). The sender encrypts the data using the receiver's public key, and the receiver decrypts it using the private key.
[0045] (2) The SRAMPUF device verifies the signature and extracts the RSA public key, generates a random 256-bit temporary session key and the hash value of the temporary session key, encrypts the temporary session key and the hash value of the temporary session key using the RSA public key, and sends the encrypted data to the mobile terminal APP.
[0046] (3) The mobile terminal APP uses the private key corresponding to the RSA public key to decrypt the encrypted data. After verification, it confirms the establishment of the data encryption transmission link and starts the encryption transmission.
[0047] (4) The mobile terminal APP sends a request.
[0048] (5) The SRAMPUF device returns response data.
[0049] (6) The session ends and the temporary session key becomes invalid.
[0050] During the data encryption transmission link establishment process of this invention, the APP sends its own RSA public key to the SRAMPUF device. The SRAMPUF device generates a temporary session key and encrypts the session key using the APP's RSA public key. Then, it returns the encrypted session key to the APP. Only those who have the private key corresponding to the public key can parse the temporary session key.
[0051] In this invention, the data link between the APP and the SRAMPUF device is encrypted using the AES-256-GCM algorithm, and the SRAMPUF device randomly generates a temporary session key. Each signature or response acquisition uses this dynamically randomly generated session key to prevent replay attacks and achieve forward security.
[0052] It should be noted that the present invention is not limited to the AES-256-GCM algorithm exemplified above, and other algorithms can also be used for encrypted transmission, which can be set as needed, and will not be elaborated here.
[0053] In this invention, transmitted data is encrypted using the AES algorithm. The key module is randomly generated and then encrypted using RSA before being sent to the APP. RSA is an asymmetric encryption algorithm used for secure data transmission. RSA uses a pair of keys: a public key (publicly available for encryption) and a private key (secretly kept for decryption). The sender encrypts the data using the receiver's public key, and the receiver decrypts it using the private key.
[0054] The app sends its public key to the device, which generates a session key and encrypts it using the app's public key. The encrypted session key is then returned to the app. Only the app with the private key corresponding to the public key can parse the temporary session key.
[0055] S4, the server uses a challenge-response mechanism to authenticate SRAMPUF devices for login.
[0056] like Figure 2 As shown, the authentication process of the login management mechanism includes: (1) The server initiates a random challenge C to the mobile terminal APP, and the mobile terminal APP sends the random challenge to the SRAMPUF device through a data encryption transmission link. The random challenge C includes the input random value.
[0057] (2) The SRAMPUF device generates a PUF response R based on the random value input in the random challenge, and signs the challenge using the Elliptic Curve Digital Signature (ECDSA) algorithm to generate an ECDSA signature (R, Sig). The server verifies the ECDSA signature (R, Sig) using a pre-registered public key. The ECDSA signature (R, Sig) is generated by the PUF device signing the hash value of the PUF response using the key PUF_Key.
[0058] Specifically, ECDSA signatures use the PUF_Key (hardware root key), which is derived from the SRAMPUF hardware response. The PUF_Key is characterized by device uniqueness, long-term stability, confidentiality, and non-changeability across sessions. In other words, the PUF_Key is generated by the SRAMPUF device and derived from the PUF_Response hardware characteristics.
[0059] The purpose of PUF_Key is to use it as an ECDSA private key to sign PUF_Response, thereby completing identity authentication and proving that it is genuine hardware.
[0060] PUF_Key = F(PUF_Response). If the length of PUF_Response is incorrect, ECDSA cannot directly use it, so the signature standard makes... The method is to first hash and compress it to a fixed length, where the hash serves to fix the length.
[0061] It should be noted that in the Elliptic Curve Digital Signature (ECDSA) algorithm, the signature is usually represented by a pair of values (R, Sig). Here, R represents a random number generated based on the input; Sig represents the PUF signature data for Hash(C||R)).
[0062] (3) The server obtains the signature (R, Sig) of the challenge C, verifies the validity of the ECDSA signature (R, Sig) using the pre-registered public key, and determines whether the signature is a legal signature for the hash value Hash(C) of the random challenge C. If it meets the requirements, it determines that the login authentication is successful and returns the authentication result to the APP.
[0063] The following is an explanation of the specific process of verifying the signature with the pre-registered public key and matching the hash value: Device side: The PUF generates a response: R = PUF(C), then calculates the hash: H = Hash(C). Use PUF_Key to perform ECDSA signature: (R, Sig) = ECDSA_Sign(PUF_Key, H). Then send (R, Sig) to the server.
[0064] Server side: Holding the pre-registered public key PK, use PK to verify whether the signature is legal and verify whether the signature content is equal to the saved Hash(C) by itself. If both verifications pass, it is determined that the authentication is successful.
[0065] Sig·G = Hash(C)·G + PK·R (mod n) Among them, PK is the pre-registered public key; C is the server challenge; (R, Sig) is the ECDSA signature returned by the device; G is a fixed value. If the verification passes, it is judged as a genuine device.
[0066] The following is an explanation of the ECDSA signature algorithm.
[0067] ECDSA is a signature scheme based on elliptic curve cryptography, used to verify data integrity and identity authentication.
[0068] In this invention, the ECDSA signature algorithm uses the BK_ECC_CURVE_NIST_P521 algorithm. BK_ECC_CURVE_NIST_P521 is an elliptic curve defined by NIST (National Institute of Standards and Technology), which is part of elliptic curve cryptography (ECC).
[0069] The signature process of the ECDSA signature algorithm includes: [[ID=2�]] 1. Select an elliptic curve Ep(a, b) and a base point G; 2. Select a private key k (k < n, n is the order of G), and calculate the public key K = kG using the base point G; 3. Generate a random integer r (r < n) and calculate the point R = rG; 4. Use the original data and the coordinate values x, y of the point R as parameters, calculate SHA1 as the hash, that is, Hash = SHA1(original data, x, y); 5. Calculate s≡r-Hash*k(mod n); 6. r and s are used as signature values. If either r or s is 0, start executing from step 3 again.
[0070] The verification process is as follows: 1. The recipient receives the message (m) and the signature value (r, s).
[0071] 2. Calculate: sG+H(m)P=(x1,y1),r1≡x1modp.
[0072] 3. Verify the equation: r1≡rmodp.
[0073] 4. If the equation is true, the signature is accepted; otherwise, the signature is invalid.
[0074] This invention adopts an integrated SRAMPUF+ECDSA signature architecture. The FPGA is used to extract the entropy source of the SRAM initial state upon power-on and dynamically generate a unique and stable PUF key. The same FPGA hardware resources are reused to implement the ECDSA signature algorithm.
[0075] Physical characteristics of SRAM: Data in SRAM (Static Random Access Memory) is lost after power is turned off, but when power is turned on, the uninitialized memory cells will exhibit random but relatively stable "0" or "1" states. This randomness stems from minute differences in the manufacturing process (such as transistor threshold voltage fluctuations), making it an ideal source of physically unclonable function (PUF) entropy.
[0076] In this invention, the FPGA chip extracts the entropy source from the initial power-on state of the SRAM and dynamically generates the PUF key PUF_Key, including: (1) SRAM power-on initial state acquisition: When the FPGA is powered on, the SRAM is not initialized and each memory cell presents a random state (some are 0 and some are 1). Quickly read the initial value of the SRAM (usually completed in milliseconds to avoid data loss after the circuit stabilizes).
[0077] (2) Entropy source extraction and stability processing Raw entropy extraction: Directly read the initial bit sequence of SRAM (e.g., 1024 bits) to extract the raw entropy, but there is noise (some bits may change with each power-on).
[0078] Fuzzy extraction: Ensures reliable extraction and reconstruction of the key from the physical randomness of SRAM, correcting minor deviations (noise) during reading using error-correcting codes (such as BCH codes). It transforms unstable physical random values into stable digital keys (e.g., for encryption).
[0079] (3) Dynamic PUF key generation Temporary key generation: The SRAM entropy source is re-extracted each time power is applied to dynamically generate a unique and stable PUF key PUF_Key for the device. After use, the intermediate data in the SRAM is cleared to ensure that no key remains.
[0080] S5 performs asset access and asset encryption based on the key PUF_Key, the hash value of the PUF response, and the asset access credential.
[0081] This step implements an asset binding mechanism, using a key generated by PUF to encrypt asset access credentials, binding the asset access policy to PUF response characteristics, and achieving a chip-as-a-vault security model. Asset management includes: asset access and asset encryption.
[0082] like Figure 3 As shown, the asset access process includes: First, after receiving a user's asset access request, the APP challenges the SRAMPUF device, which then returns an ECDSA signature (R, Sig). The ECDSA signature (R, Sig) is generated by the PUF device signing the hash value of the PUF response using the key PUF_Key.
[0083] Then, the app calculates Key'=Hash(C||R) based on the random challenge C and the component R in the signature, and sends it to the encryption engine. The encryption engine uses the key Key' to decrypt the asset in the asset library and returns the decrypted plaintext asset to the user. Here, Key'=Hash(C+R).
[0084] Key' comes from the R in the challenge C+signature returned by the server / device, and its role is the asset decryption key. Key' is characterized by changing dynamically with each session, being publicly computable, and being used only for decrypting assets.
[0085] In this invention, the R value for calculating Key' comes from an ECDSA signature, which is generated using a PUF_Key. Without a valid PUF_Key, a valid R cannot be generated, rendering Key' invalid. Only a genuine device can generate a valid R value; therefore, although Key' is calculated by the app, it must rely on genuine hardware to be legally obtained.
[0086] like Figure 4 As shown, the asset encryption process includes: First, after receiving the user's asset access request, the APP challenges the SRAMPUF device, and the SRAMPUF device returns an ECDSA signature (R, Sig). The ECDSA signature (R, Sig) is generated by the PUF device signing the hash value of the PUF response using the key PUF_Key.
[0087] Then, the app calculates the key Key' = Hash(C||R) based on the random challenge C and the component R in the ECDSA signature, and sends it to the encryption engine. The encryption engine uses the key Key' to encrypt the assets given in the asset pool. Wherein, Key' = Hash(C+R).
[0088] like Figure 6 As shown, the dynamic digital signature generated by the SRAMPUF device is transmitted between the NFC tag on the mobile terminal and the SRAMPUF device via Bluetooth chip (BLE), ensuring that the device identity cannot be forged. This fundamentally solves the problems of key storage risk, high energy consumption and inconvenient deployment that exist in traditional security solutions, and provides a secure, portable and low-power digital asset management solution for IoT edge devices.
[0089] The hardware circuit used in this invention employs a two-stage power supply method. The Bluetooth chip controls the power supply to the FPGA chip and subsequent circuits such as the electronic screen (e.g., e-ink screen). Power is supplied to the subsequent circuits when a signature or authentication operation is initiated (during authentication initiation or wake-up). The power supply to the subsequent circuits is immediately cut off after the FPGA chip returns authentication data, thereby reducing the operating power and standby power consumption of the subsequent circuits. The Bluetooth operating power consumption is 5mA, and the FPGA operating power consumption is 15mA. This method reduces the operating power consumption by 75%. Since there is no need to consider the standby power consumption of the FPGA, higher performance and larger scale FPGA chips can be selected during the design, expanding the upper limit of computing power and functional integration.
[0090] This invention achieves optimal power consumption by using a two-stage power supply method, where the Bluetooth chip controls the power supply of subsequent circuits such as the FPGA and e-ink screen, and uses NFC to wake up the Bluetooth chip in the device, which is in a sleep state by default.
[0091] In this invention, both the NFC data of the NFC tag and the Bluetooth name of the Bluetooth chip are equipped with a unique device identifier (DID) to enable the mobile terminal to match the corresponding SRAMPUF device during the touch process. This allows the mobile device to quickly match the device with a simple tap, greatly simplifying the user's steps.
[0092] Meanwhile, NFC has built-in NDEF data that can trigger a specific app to pop up on a mobile phone or tablet. The app launch field in the NDEF data is configurable, and users can adapt their own apps according to their needs.
[0093] Specifically, NFCNDEF (NFC Data Exchange Format) is a standardized data format defined by the NFC Forum for exchanging information between NFC devices or tags. NFCNDEF specifies how structured data is stored, ensuring that devices from different manufacturers can recognize and parse each other's content.
[0094] The NDEF field records the application package name and URI. When the phone touches the NFC tag, the corresponding app pops up. In this invention, the NDEF field of the NFC tag is readable and writable. By modifying this field, different apps can be launched. Users can write their own application package name and URI records into the NDEF field to launch their own app by touching the tag.
[0095] This invention employs a minimalist design based on e-ink displays, making it easy to integrate into badges or other creative products. Users can personalize their wallets by changing the image on the e-ink display via a mini-program, allowing them to create their own unique style.
[0096] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the embodiments of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the protection scope of the present invention.
Claims
1. A digital asset protection method utilizing SRAMPUF features, characterized in that, include: S1. Configure a unique device identifier (DID) for the SRAMPUF device. The SRAMPUF device is implemented using an FPGA chip, and the unique ID number of the FPGA chip is concatenated by a public key hash as the unique device identifier (DID). S2, The device unique identifier DID is pre-set in the NFC tag. When the mobile terminal touches the SRAMPUF device with NFC, it supports NFC touch wake-up and automatically launches the matching APP. The SRAMPUF device is identified according to the pre-set device unique identifier DID, and the connection between the matching APP on the mobile terminal and the SRAMPUF device is started. S3, establish an encrypted data transmission link between the APP and the SRAMPUF device. In each session, the APP and the SRAMPUF device use a dynamically and randomly generated temporary session key to encrypt the transmitted data. S4, the server uses a challenge-response mechanism to authenticate SRAMPUF devices, including: The server sends a random challenge to the mobile terminal APP, and the mobile terminal APP sends the random challenge to the SRAMPUF device through a data encryption transmission link. The SRAMPUF device generates a PUF response based on the random value input in the random challenge, and signs the challenge using the Elliptic Curve Digital Signature (ECDSA) algorithm to generate an ECDSA signature (R, Sig). The server verifies the ECDSA signature (R, Sig) using a pre-registered public key. The ECDSA signature (R, Sig) is generated by the PUF device signing the hash value of the PUF response using the key PUF_Key. S5. Perform asset access and asset encryption based on the key PUF_Key, the hash value of the PUF response, and the asset access credential.
2. The digital asset protection method utilizing SRAMPUF characteristics according to claim 1, characterized in that, Establish an encrypted data transmission link between the APP and the SRAMPUF device, including: The app sends the RSA public key to the SRAMPUF device with a digital signature; The SRAMPUF device verifies the signature and extracts the RSA public key, generates a random temporary session key and its hash value, encrypts the temporary session key and its hash value using the RSA public key, and then sends the encrypted data to the APP. The app uses the private key corresponding to the RSA public key to decrypt the encrypted data. After verification, the encrypted data transmission link is established and encrypted transmission is started.
3. A digital asset protection method utilizing SRAMPUF characteristics according to claim 1, characterized in that, In S3, the data link between the APP and the SRAMPUF device is encrypted using the AES-256-GCM algorithm, and the SRAMPUF device randomly generates a temporary session key.
4. A digital asset protection method utilizing SRAMPUF characteristics according to claim 1, characterized in that, In S4, the server uses the pre-registered public key to verify the ECDSA signature (R, Sig) and determines whether the signature is a valid signature of the hash value Hash(C) of the random challenge C. If it is valid, the login authentication is successful and the authentication result is returned to the APP.
5. A digital asset protection method utilizing SRAMPUF characteristics according to claim 1, characterized in that, In S4, the FPGA chip extracts the entropy source from the initial power-on state of the SRAM and dynamically generates a unique and stable PUF key PUF_Key, including: When the FPGA is powered on, the SRAM is not initialized and each memory cell is in a random state. The initial value of the SRAM is read. Read the initial bit sequence of the SRAM, extract the original entropy, ensure that the key is reliably extracted and reconstructed from the physical randomness of the SRAM, and correct the deviation during reading using error correction codes; Each time power is applied, the SRAM entropy source is re-extracted to dynamically generate a unique and stable PUF key PUF_Key for the device. After use, the intermediate data in the SRAM is cleared to ensure that no key remains.
6. A digital asset protection method utilizing SRAMPUF characteristics according to claim 1, characterized in that, In S5, the asset access includes: After receiving a user's asset access request, the APP challenges the SRAMPUF device, which returns an ECDSA signature (R, Sig). The ECDSA signature (R, Sig) is generated by the PUF device signing the hash value of the PUF response using the key PUF_Key. The APP calculates Key'=Hash(C||R) based on the random challenge C and the component R in the signature, and sends it to the encryption engine. The encryption engine uses the key Key' to decrypt the asset in the asset library and returns the decrypted plaintext asset to the user.
7. A digital asset protection method utilizing SRAMPUF characteristics according to claim 1, characterized in that, In S5, the asset encryption includes: After receiving a user's asset access request, the APP challenges the SRAMPUF device, which returns an ECDSA signature (R, Sig). The ECDSA signature (R, Sig) is generated by the PUF device signing the hash value of the PUF response using the key PUF_Key. The APP calculates the key Key'=Hash(C||R) based on the random challenge C and the component R in the ECDSA signature, and sends it to the encryption engine. The encryption engine uses the key Key' to encrypt the assets given in the asset library.
8. A digital asset protection method utilizing SRAMPUF characteristics according to claim 1, characterized in that, The dynamic digital signature generated by the SRAMPUF device is transmitted between the mobile terminal NFC tag and the SRAMPUF device via a Bluetooth chip.
9. A digital asset protection method utilizing SRAMPUF characteristics according to claim 8, characterized in that, The system employs a two-stage power supply method, where the Bluetooth chip controls the power supply of the FPGA chip. When authentication is initiated or the device is woken up, the Bluetooth chip supplies power to the downstream circuit. Once the FPGA chip returns authentication data, it immediately cuts off the power to the downstream circuit.
10. A digital asset protection method utilizing SRAMPUF characteristics according to claim 8, characterized in that, Both the NFC data of the NFC tag and the Bluetooth name of the Bluetooth chip are equipped with the device unique identifier (DID) to enable the mobile terminal to match the corresponding SRAMPUF device during the touch process.