Secret Key Scheme Research Articles

Secrecy Capacity Region of the AWGN MAC with External Eavesdropper and Feedback.

For the point-to-point additive white Gaussian noise (AWGN) channel with an eavesdropper and feedback, it has already been shown that the secrecy capacity can be achieved by a secret key-based feedback scheme, where the channel feedback is used for secret sharing, and then encrypting the transmitted message by the shared key. By secret sharing, any capacity-achieving coding scheme for the AWGN channel without feedback can be secure by itself, which indicates that the capacity of the same model without the secrecy constraint also affords an achievable secrecy rate to the AWGN channel with an eavesdropper and feedback. Then it is natural to ask: is the secret key-based feedback scheme still the optimal scheme for the AWGN multiple-access channel (MAC) with an external eavesdropper and channel feedback (AWGN-MAC-E-CF), namely, achieving the secrecy capacity region of the AWGN-MAC-E-CF? In this paper, we show that the answer to the aforementioned question is no, and propose the optimal feedback coding scheme for the AWGN-MAC-E-CF, which combines an existing linear feedback scheme for the AWGN MAC with feedback and the secret key scheme in the literature. This paper provides a way to find optimal coding schemes for AWGN multi-user channels in the presence of an external eavesdropper and channel feedback.

Tapping Eavesdropper Designs Against Physical Layer Secret Key in Point-to-Point Fiber Communications

With the growing demand for service access and data transmission, security issues in optical fiber systems have become increasingly important and the subject of increased research. Physical layer secret key generation (PL-SKG), which leverages the random but common channel properties at legitimate parties, has been shown to be a secure, low-cost, and easily deployed technique as opposed to computational-based cryptography, quantum, and chaos key methods that rely on precise equipment. However, the eavesdropper (Eve) potential for current PL-SKG in fiber communications has been overlooked by most studies to date. Unlike wireless communications, where the randomness comes from the spatial multi-paths that cannot be all captured by Eves, in fiber communications, all the randomness (from transmitted random pilots or channel randomness) is contained in the signals transmitted inside the fiber. This, therefore, enables a tapping Eve to reconstruct the common features of legitimate users from its received signals, and further decrypt the featured-based secret keys. To implement this idea, we designed two Eve schemes against polarization mode distortion (PMD) based PL-SKG and the two-way cross multiplication based PL-SKG. The simulation results show that our proposed Eves can successfully reconstruct the legitimate common feature and the secret key relied upon, leading to secret key rate (SKR) reductions of between three and four orders of magnitude in the PL-SKG schemes studied. As a result, we reveal and demonstrate a novel eavesdropping potential to provide challenges for current physical layer secret key designs. We hope to provide more insightful vision and critical evaluation on the design of new physical layer secret key schemes in optical fiber links, to provide more comprehensively secure, and intelligent optical networks.

Key-Recovery Attacks on ASASA

The $$\mathsf {ASASA}$$ construction is a new design scheme introduced at Asiacrypt 2014 by Biryukov, Bouillaguet and Khovratovich. Its versatility was illustrated by building two public-key encryption schemes, a secret-key scheme, as well as super S-box subcomponents of a white-box scheme. However, one of the two public-key cryptosystems was recently broken at Crypto 2015 by Gilbert, Plut and Treger. As our main contribution, we propose a new algebraic key-recovery attack able to break at once the secret-key scheme as well as the remaining public-key scheme, in time complexity $$2^{63}$$ and $$2^{39}$$ , respectively (the security parameter is 128 bits in both cases). Furthermore, we present a second attack of independent interest on the same public-key scheme, which heuristically reduces the problem of breaking the scheme to an $$\mathsf {LPN}$$ instance with tractable parameters. This allows key recovery in time complexity $$2^{56}$$ . Finally, as a side result, we outline a very efficient heuristic attack on the white-box scheme, which breaks instances claiming 64 bits of security under one minute on a laptop computer.

Mirror theory and cryptography

“Mirror Theory” is the theory that evaluates the number of solutions of affine systems of equalities $$({=})$$ and non equalities ( $$\ne $$ ) in finite groups. It is deeply related to the security and attacks of many generic cryptographic secret key schemes, for example random Feistel schemes (balanced or unbalanced), Misty schemes, Xor of two pseudo-random bijections to generate a pseudo-random function etc. In this paper we will assume that the groups are abelian. Most of time in cryptography the group is $$((\mathbb {Z}/2\mathbb {Z})^n, \oplus )$$ and we will concentrate this paper on these cases. We will present here general definitions, some theorems, and many examples and computer simulations.

A Secure Information Transmission Scheme With a Secret Key Based on Polar Coding

In this letter, a new secure information transmission scheme based on polar codes with a pre-shared secret key is proposed. In polar codes, after the channel polarization is induced, good split channels are used to transmit the user message and bad channels are utilized to support the reconstruction of the message by sharing fixed information. If the fixed information in bad channels is secret, an adversary gets difficulty in reconstructing the user message in good channels without knowledge of the fixed information. From this observation, we construct a secure information transmission scheme. By appending pre-/post-processing that imposes a dependency between the transmitted message sub-blocks, the adversary's difficulty can be changed to an intractability, since only partial information can be decodable by attackers. A new class of secret key scheme is developed in such a way.

Weaknesses of North American wireless authentication protocol

Security for cellular and PCS systems in the United States will be based on secret key schemes for authentication and encryption. The effectiveness of security for wireless, as in other applications of cryptography, will depend on the ability of the basic cryptographic algorithms to withstand attacks and on sound protocol design. We show the IS-41 authentication protocol to be unsound by pointing to multiple flaws in the protocol which allow a network impersonator to gain service without "breaking the CAVE algorithm". These flaws effectively nullify authentication.