Improving the Performance of the SYND Stream Cipher

International audience. In 2007, Gaborit et al. proposed the stream cipher SYND as an improvement of the pseudo random number generator due to Fischer and Stern. This work shows how to improve considerably the e ciency the SYND cipher without using the so-called regular encoding and without compromising the security of the modi ed SYND stream cipher. Our proposal, called XSYND, uses a generic state transformation which is reducible to the Regular Syndrome Decoding problem (RSD), but has better computational characteristics than the regular encoding. A rst implementation shows that XSYND runs much faster than SYND for a comparative security level (being more than three times faster for a security level of 128 bits, and more than 6 times faster for 400-bit security), though it is still only half as fast as AES in counter mode. Parallel computation may yet improve the speed of our proposal, and we leave it as future research to improve the e ciency of our implementation

Timing attacks: symbolic framework and proof techniques

We propose a framework for timing attacks, based on (a variant of) the applied-pi calculus. Since many privacy properties, as well as strong secrecy and game-based security properties, are stated as process equivalences, we focus on (time) trace equivalence. We show that actually, considering timing attacks does not add any complexity: time trace equivalence can be reduced to length trace equivalence, where the attacker no longer has access to execution times but can still compare the length of messages. We therefore deduce from a previous decidability result for length equivalence that time trace equivalence is decidable for bounded processes and the standard cryptographic primitives. As an application, we study several protocols that aim for privacy. In particular, we (automatically) detect an existing timing attack against the biometric passport and new timing attacks against the Private Authentication protocol

Faster and timing-attack resistant AES-GCM

We present a bitsliced implementation of AES encryption in counter mode for 64-bit Intel processors. Running at 7.59 cycles/byte on a Core 2, it is up to 25% faster than previous implementations, while simultaneously offering protection against timing attacks. In particular, it is the only cache-timing-attack resistant implementation offering competitive speeds for stream as well as for packet encryption: for 576-byte packets, we improve performance over previous bitsliced implementations by more than a factor of 2. We also report more than 30% improved speeds for lookup-table based Galois/Counter mode authentication, achieving 10.68 cycles/byte for authenticated encryption. Furthermore, we present the first constant-time implementation of AES-GCM that has a reasonable speed of 21.99 cycles/byte, thus offering a full suite of timing-analysis resistant software for authenticated encryption

A new combinational logic minimization technique with applications to cryptology

to cryptology

hacspec: Towards Verifiable Crypto Standards

International audienceWe present hacspec, a collaborative effort to design a formal specification language for cryptographic primitives. Specifications (specs) written in hacspec are succinct, easy to read and implement, and lend themselves to formal verification using a variety of existing tools. The syntax of hacspec is similar to the pseudocode used in cryptographic standards but is equipped with a static type system and syntax checking tools that can find errors. Specs written in hacspec are executable and can hence be tested against test vectors taken from standards and specified in a common format. Finally, hacspec is designed to be compilable to other formal specification languages like F⋆, EasyCrypt, Coq, and cryptol, so that it can be used as the basis for formal proofs of functional correctness and cryptographic security using various verification frameworks. This paper presents the syntax, design, and tool architecture of hacspec. We demonstrate the use of the language to specify popular cryptographic algorithms, and describe preliminary compilers from hacspec to F⋆ and to EasyCrypt. Our goal is to invite authors of cryptographic standards to write their pseudocode in hacspec and to help the formal verification community develop the language and tools that are needed to promote high-assurance cryptographic software backed by mathematical proofs

All the AES You Need on Cortex-M3 and M4

Contains fulltext : 178459.pdf (preprint version ) (Open Access) Contains fulltext : 178459pub.pdf (publisher's version ) (Closed access)nul

Assembly or Optimized C for Lightweight Cryptography on RISC-V?

Item does not contain fulltextCANS 202

Faster ECC over F2521−1\mathbb{F}_{2^{521}-1}

In this paper we present a new multiplication algorithm for residues modulo the Mersenne prime $2^{521}−1$. Using this approach, on an Intel Haswell Core i7-4770, constant-time variable-base scalar multiplication on NIST’s (and SECG’s) curve P-521 requires 1,108,000 cycles, while on the recently proposed Edwards curve E-521 it requires just 943,000 cycles. As a comparison, on the same architecture openSSL’s ECDH speed test for curve P-521 requires 1,319,000 cycles. Furthermore, our code was written entirely in C and so is robust across different platforms. The basic observation behind these speedups is that the form of the modulus allows one to multiply residues with as few word-by-word multiplications as is needed for squaring, while incurring very little overhead from extra additions, in contrast to the usual Karatsuba methods