We introduce a novel approach to constructing ternary addressable physically unclonable functions (TAPUFs) using magnetoresistive random-access memory (MRAM) devices. TAPUFs use three states (1, 0, and X) to track unstable cells. The proposed TAPUF leverages the resistance properties of MRAM cells to produce unique digital fingerprints that can be effectively utilized in cryptographic protocols. We exploit the cell-to-cell variations in resistance values to generate reliable cryptographic keys and true random numbers, which can add protection against certain attacks. To evaluate the performance of the TAPUF, various tests were conducted, including assessments of inter-cell to intra-cell variation, inter-distance, bit error rate (BER), and temperature variation. These experiments were conducted using a low-power client device to replicate practical scenarios. The obtained results demonstrate that the proposed TAPUF exhibits exceptional scalability, energy efficiency, and reliability.

In the proposed protocol, a trusted entity interacts with the terminal device of each user to verify the legitimacy of the public keys without having access to the private keys that are generated and kept totally secret by the user. The protocol introduces challenge–response–pair mechanisms enabling the generation, distribution, and verification of cryptographic public–private key pairs in a distributed network with multi-factor authentication, tokens, and template-less biometry. While protocols using generic digital signature algorithms are proposed, the focus of the experimental work was to implement a solution based on Crystals-Dilithium, a post-quantum cryptographic algorithm under standardization. Crystals-Dilithium generates public keys consisting of two interrelated parts, a matrix generating seed, and a vector computed from the matrix and two randomly picked vectors forming the secret key. We show how such a split of the public keys lends itself to a two-way authentication of both the trusted entity and the users.

In this study, we present the Response-Based Key Encapsulation Mechanism (R-KEM), an ephemeral key encapsulation and recovery scheme tailored for cryptographic systems in high-noise, high-jamming network environments. By adopting the Challenge–Response Pair (CRP) mechanism for both key encapsulation and authentication, R-KEM eliminates the need to store secret keys on the device, favoring on-demand key generation. By maintaining only encrypted data on the device, R-KEM significantly enhances security, ensuring that in the event of an attack, no sensitive information can be compromised. Its novel error-correcting strategy efficiently corrects 20 to 23 bits of errors promptly, eliminating the need for redundant helper data and fuzzy extractors. R-KEM is ideally suited for terminal devices with constrained computational resources. Our comprehensive performance analysis underscores R-KEM’s ability to recover error-free cryptographic keys in noisy networks, offering a superior alternative to conventional methods that struggle to maintain secure data transmission under such challenges. This work not only demonstrates R-KEM’s efficacy but also paves the way for more resilient cryptographic systems in noise-prone environments.

Crypto wallets store and protect the private keys needed to sign transactions for crypto currencies; they are secured by multi-factor authentication schemes. However, the loss of a wallet, or a dysfunctional factor of authentication, can be catastrophic, as the keys are then lost as well as the crypto currencies. Such difficult tradeoffs between the protection of the private keys and factors of authentication that are easy to use are also present in public key infrastructures, banking cards, smartphones and smartcards. In this paper, we present protocols based on novel challenge–response pair mechanisms that protect private keys, while using factors of authentication that can be lost or misplaced without negative consequences. Examples of factors that are analyzed include passwords, tokens, wearable devices, biometry, and blockchain-based non-fungible tokens. In normal operations, the terminal device uses all factors of authentication to retrieve an ephemeral key, decrypt the private key, and finally sign a transaction. With our solution, users can download the software stack into multiple terminal devices, turning all of them into backups. We present a zero-knowledge multi-factor authentication scheme allowing the secure recovery of private keys when one of the factors is lost, such as the token. The challenge–response pair mechanisms also enable a novel key pair generation protocol in which private keys can be kept secret by the user, while a Keystore can securely authenticate the user and transmit the public key to a distributed network. The standardized LWE post-quantum cryptographic CRYSTALS Dilithium protocol was selected in the experimental section.

This work proposes a lightweight biometric key-binding scheme that adapts a PUF-style challenge–response mechanism to face geometry: a two-factor password and session nonce generate random challenge points, Gray-coded Euclidean distances to facial landmarks form responses, and a random key is bound by discarding selected positions so only a reduced subset, the nonce, and a key hash are stored. At authentication, a fresh response set is compared to the subset with a Hamming-distance tolerance, and bounded local search corrects residual errors; each successful session rotates the nonce and refreshes the ephemeral key. We frame this as a conceptual exploration of an interpretable, on-device, controlled-capture design niche—a per-session nonce-driven cancelable biometric key-binding mechanism—and we quantify the resulting security–usability trade-offs. Empirically, the scheme works under stable capture conditions with carefully tuned thresholds, and it is naturally suited to tightly controlled deployments (e.g., access kiosks) where it can also incorporate user-driven micro-gestures as an extra behavioral factor. While the construction is fragile under broader variability and leans on the second factor for security, it offers an alternative to existing mechanisms and a clear niche, and we present it as a conceptual exploration showing how CRP mechanisms can inform cancelable biometrics with per-session revocability.