S-box

Abstract: Compact and high-speed hardware architectures and logic optimization methods for the AES algorithm Rijndael are described. Encryption and decryption data paths are combined and all arithmetic components are reused. By introducing a new composite field, the S-Box structure is also optimized. An extremely small size of 5.4 Kgates is obtained for a 128-bit key Rijndael circuit using a 0.11-µm CMOS standard cell library. It requires only 0.052 mm2 of area to support both encryption and decryption with 311 Mbps throughput. By making effective use of the SPN parallel feature, the throughput can be boosted up to 2.6 Gbps for a high-speed implementation whose size is 21.3 Kgates.

Abstract: Cryptography is ubiquitous and plays a key role in ensuring data secrecy and integrity as well as in securing computer systems more broadly. Introduction to Modern Cryptography provides a rigorous yet accessible treatment of this fascinating subject. The authors introduce the core principles of modern cryptography, with an emphasis on formal definitions, clear assumptions, and rigorous proofs of security. The book begins by focusing on private-key cryptography, including an extensive treatment of private-key encryption, message authentication codes, and hash functions. The authors also present design principles for widely used stream ciphers and block ciphers including RC4, DES, and AES, plus provide provable constructions of stream ciphers and block ciphers from lower-level primitives. The second half of the book covers public-key cryptography, beginning with a self-contained introduction to the number theory needed to understand the RSA, Diffie-Hellman, and El Gamal cryptosystems (and others), followed by a thorough treatment of several standardized public-key encryption and digital signature schemes. Integrating a more practical perspective without sacrificing rigor, this widely anticipated Second Edition offers improved treatment of: Stream ciphers and block ciphers, including modes of operation and design principles Authenticated encryption and secure communication sessions Hash functions, including hash-function applications and design principles Attacks on poorly implemented cryptography, including attacks on chained-CBC encryption, padding-oracle attacks, and timing attacks The random-oracle model and its application to several standardized, widely used public-key encryption and signature schemes Elliptic-curve cryptography and associated standards such as DSA/ECDSA and DHIES/ECIES Containing updated exercises and worked examples, Introduction to Modern Cryptography, Second Edition can serve as a textbook for undergraduate- or graduate-level courses in cryptography, a valuable reference for researchers and practitioners, or a general introduction suitable for self-study.

Abstract: This paper is devoted to the analysis of the impact of chaos-based techniques on block encryption ciphers. We present several chaos based ciphers. Using the well-known principles in the cryptanalysis we show that these ciphers do not behave worse than the standard ones, opening in this way a novel approach to the design of block encryption ciphers.

Abstract: A key step in the Advanced Encryption Standard (AES) algorithm is the “S-box.” Many implementations of AES have been proposed, for various goals, that effect the S-box in various ways. In particular, the most compact implementations to date of Satoh et al.[14] and Mentens et al.[6] perform the 8-bit Galois field inversion of the S-box using subfields of 4 bits and of 2 bits. Our work refines this approach to achieve a more compact S-box. We examined many choices of basis for each subfield, not only polynomial bases as in previous work, but also normal bases, giving 432 cases. The isomorphism bit matrices are fully optimized, improving on the “greedy algorithm.” Introducing some NOR gates gives further savings. The best case improves on [14] by 20%. This decreased size could help for area-limited hardware implementations, e.g., smart cards, and to allow more copies of the S-box for parallelism and/or pipelining of AES.