The ISC International Journal of Information Security

Abstract In the quantum computing era, classical encryption faces unprecedented vulnerabilities, while Quantum Key Distribution (QKD) alone remains insufficient for top-secret data transmission due to practical hardware flaws. In this paper, a novel dual-layered framework that integrates steganography with QKD is proposed to enhance security and concealment. The proposed protocol embeds encrypted messages within QKD keys during post-processing, leveraging existing infrastructure without requiring hardware modifications. The message is first compressed, encoded, and encrypted using a pre-shared QKD key via one-time-pad encryption. A block-based search mechanism then hides message bits within the sifted key while preserving statistical randomness. Crucially, this approach provides two-layer security: information-theoretic encryption via QKD and undetectable message existence. Evaluations confirm ultra-low failure probabilities of embedding (below 10−12 for 1000-bit messages) and minimal deviations in sifted key length (under 1% for typical blocks). The solution enables eavesdropper detection, maintaining full compatibility with standard QKD post-processing. By unifying steganographic stealth with QKD’s theoretical security, this work establishes a practical solution for transmitting top-secret data against evolving quantum threats.

Abstract Digital signatures are used to ensure legitimate access through identity authentication. They are also used in blockchains and to authenticate transactions. Code-based digital signatures are not widely used due to their complexity. This paper presents a new code-based signature algorithm with
lower complexity than existing methods and a high success rate. The key generation algorithm constructs three-tuple public keys using a dual inverse matrix. The proposed signing scheme is based on the McEliece cryptosystem. It includes an integrity check to mitigate forgery before verification.

Abstract A non-interactive (t,n)-publicly veriable secret sharing scheme (non-interactive (t,n)-PVSS scheme) is a (t,n)-secret sharing scheme in which anyone, not only the participants of the scheme, can verify the correctness of the produced shares without interacting with the dealer and participants. The (t,n)-PVSS schemes have found a lot of applications in cryptography because they are suitable for
real-life scenarios in which an external verifier is required to check the correctness of the produced shares without interacting with the dealer and participants. In this paper, we propose a non-interactive (t,n)-PVSS scheme using the non-homogeneous linear recursions (NHLRs), and prove its security with a formal method. We compare the computational complexity of our scheme with that of
Schoenmakers's scheme and show that our non-interactive (t,n)-PVSS scheme runs faster than Schoenmakers's scheme when n > 5 and n> t >(2n+9)/n. The communicational complexity of our scheme is almost equal to that of Schoenmakers's scheme.