SPHINCS+^+ post-quantum digital signature scheme with Streebog hash function

Many commonly used public key cryptosystems will become insecure once a scalable quantum computer is built. New cryptographic schemes that can guarantee protection against attacks with quantum computers, so-called post-quantum algorithms, have emerged in recent decades. One of the most promising candidates for a post-quantum signature scheme is SPHINCS$^+$, which is based on cryptographic hash functions. In this contribution, we analyze the use of the new Russian standardized hash function, known as Streebog, for the implementation of the SPHINCS$^+$ signature scheme. We provide a performance comparison with SHA-256-based instantiation and give benchmarks for various sets of parameters.Comment: 5 pages, 2 figures, 3 table

A proposed hybrid cryptography algorithm based on GOST and salsa (20)

Security concepts are frequently used interchangeably. These concepts are interrelated and share similar objectives for the protection of privacy, credibility, and access to information; however, there are some slight differences between them. Such variations lie mostly in the subject matter approach, the approaches used, and the focus fields. With the intention of protecting data in contradiction of unauthorized or unintentional disclosure, cryptography is used during transit (electronic or physical) and when data is stored. In the course of the past few years, some block ciphers and stream ciphers have been proposed. These block ciphers take encryption method that uses Substitution-Permutation and Feistel network structure while stream ciphers choose a onetime method. GOST encryption is based on the confidentiality of the secret key. However, it leads to the same ciphertext being generated when the encryption program is used with the same key for the plain text. Reproduction of messages can thus easily be identified by an opponent that is a weak link in any communication. In this paper, proposed a hybrid encryption method based on GOST block cipher and Salsa stream cipher to provide proper security with as high hardness randomly enhances the five standard tests and modifies key schedule as secure operations. The downside of the GOST algorithm is a simple key schedule so that in certain circumstances be the weak point of the method of cryptanalysis as related-key cryptanalysis. However, this resolved by the proposed method by passing the keys of GOST to Salsa stream to have the right combination and more robustness security. Its need for 2256 probable keys to breaking keys that, because of its uncomfortable procedure in this situation, is to be not used brute force attack. Correspondingly, five standard tests successfully surpassed the randomness of a proposed method

Improved Cryptanalysis on Reduced-Round GOST and Whirlpool Hash Function (Full Version)

The GOST hash function family has served as the new Russian national hash standard (GOST R 34.11-2012) since January 1, 2013, and it has two members, $i.e.$, GOST-256 and GOST-512 which correspond to two different output lengths. Most of the previous analyses of GOST emphasize on the compression function rather than the hash function. In this paper, we focus on security properties of GOST under the hash function setting. First we give two improved preimage attacks on 6-round GOST-512 compared with the previous preimage attack, $i.e.$, a time-reduced attack with the same memory requirements and a memoryless attack with almost identical time. Then we improve the best collision attack on reduced GOST-256 (resp. GOST-512) from 5 rounds to 6.5 (resp. 7.5) rounds. Finally, we construct a limited-birthday distinguisher on 9.5-round GOST using the limited-birthday distinguisher on hash functions proposed at ASIACRYPT 2013. An essential technique used in our distinguisher is the carefully chosen differential trail, which can further exploit freedom degrees in the inbound phase when launching rebound attacks on the GOST compression function. This technique helps us to reduce the time complexity of the distinguisher significantly. We apply this strategy to Whirlpool, an ISO standardized hash function, as well. As a result, we construct a limited-birthday distinguisher on 9-round Whirlpool out of 10 rounds, and reduce the time complexity of the previous 7-round distinguisher. To the best of our knowledge, all of our results are the best cryptanalytic results on GOST and Whirlpool in terms of the number of rounds analyzed under the hash function setting

Advanced truncated differential cryptanalysis of GOST block cipher

n this paper, we use the ideas presented by Courtois and Mourouzis to study the security of two variants of GOST, which are considered as the simpler and most secure variants [9]; the one with the S-boxes replaced by the Identity Map and the ISO version which is assumed to be the strongest one. The advanced differential attacks we present are of the form of Depth-First Key search, which uses a 20 round distinguisher in the middle (or equivalently 26-round distinguisher for the simpler version of GOST with Identity Map) [11]. The main idea is that we consider a partition of the 32 rounds by placing in the middle the constructed distinguisher. Then, based on the weak diffusion we can extend these very strong statistical distinguishers to efficiently good filters for some external rounds. Then, by guessing some key bits for external rounds and determining some plaintext and ciphertext pairs of specified input-output differences we can extend the construction to an attack against the full block cipher. Thus, the technique we apply is a generic cryptanalytic framework of First-Search key search type which involves several optimization tasks obtained from the specific structure of the given encryption algorithm

Integral Distinguishers for Reduced-round Stribog

In January 2013, the Stribog hash function officially replaced GOST R 34.11-94 as the new Russian cryptographic hash standard GOST R 34.11-2012. Stribog is an AES-based primitive and is considered as an asymmetric reply to the new SHA-3 selected by NIST. In this paper we investigate the structural integral properties of reduced version of the Stribog compression function and its internal permutation. Specifically, we present a forward and backward higher order integrals that can be used to distinguish 4 and 3.5 rounds, respectively. Moreover, using the start from the middle approach, we combine the two proposed integrals to get 6.5-round and 7.5-round distinguishers for the internal permutation and 6-round and 7-round distinguishers for the compression function

Improved (Pseudo) Preimage Attacks on Reduced-Round GOST and Grøstl-256 and Studies on Several Truncation Patterns for AES-like Compression Functions (Full Version)

In this paper, we present improved preimage attacks on the reduced-round \texttt{GOST} hash function family, which serves as the new Russian hash standard, with the aid of techniques such as the rebound attack, the Meet-in-the-Middle preimage attack and the multicollisions. Firstly, the preimage attack on 5-round \texttt{GOST-256} is proposed which is the first preimage attack for \texttt{GOST-256} at the hash function level. Then we extend the (previous) attacks on 5-round \texttt{GOST-256} and 6-round \texttt{GOST-512} to 6.5 and 7.5 rounds respectively by exploiting the involution property of the \texttt{GOST} transposition operation. Secondly, inspired by the preimage attack on \texttt{GOST-256}, we also study the impacts of four representative truncation patterns on the resistance of the Meet-in-the-Middle preimage attack against \texttt{AES}-like compression functions, and propose two stronger truncation patterns which make it more difficult to launch this type of attack. Based on our investigations, we are able to slightly improve the previous pseudo preimage attacks on reduced-round \texttt{Grøstl-256}

An Improved Differential Attack on Full GOST

GOST 28147-89 is a well-known block cipher. Its large key size of 256 bits and incredibly low implementation cost make it a plausible alternative for AES-256 and triple DES. Until 2010 \despite considerable cryptanalytic efforts spent in the past 20 years", GOST was not broken see [30]. Accordingly, in 2010 GOST was submitted to ISO 18033 to become a worldwide industrial encryption standard. In paper we focus on the question of how far one can go in a dedicated Depth-First-Search approach with several stages of progressive guessing and filtering with successive distinguishers. We want to design and optimized guess-then-truncated differential attack on full 32-bit GOST and make as as efficient as we can. The main result of this paper is a single key attack against full 32-round 256-bit GOST with time complexity of 2^179 which is substantially faster than any other known single key attack on GOS

Cryptanalysis of Some AES-based Cryptographic Primitives

Current information security systems rely heavily on symmetric key cryptographic primitives as one of their basic building blocks. In order to boost the efficiency of the security systems, designers of the underlying primitives often tend to avoid the use of provably secure designs. In fact, they adopt ad hoc designs with claimed security assumptions in the hope that they resist known cryptanalytic attacks. Accordingly, the security evaluation of such primitives continually remains an open field. In this thesis, we analyze the security of two cryptographic hash functions and one block cipher. We primarily focus on the recent AES-based designs used in the new Russian Federation cryptographic hashing and encryption suite GOST because the majority of our work was carried out during the open research competition run by the Russian standardization body TC26 for the analysis of their new cryptographic hash function Streebog. Although, there exist security proofs for the resistance of AES- based primitives against standard differential and linear attacks, other cryptanalytic techniques such as integral, rebound, and meet-in-the-middle attacks have proven to be effective. The results presented in this thesis can be summarized as follows: Initially, we analyze various security aspects of the Russian cryptographic hash function GOST R 34.11-2012, also known as Streebog or Stribog. In particular, our work investigates five security aspects of Streebog. Firstly, we present a collision analysis of the compression function and its in- ternal cipher in the form of a series of modified rebound attacks. Secondly, we propose an integral distinguisher for the 7- and 8-round compression function. Thirdly, we investigate the one wayness of Streebog with respect to two approaches of the meet-in-the-middle attack, where we present a preimage analysis of the compression function and combine the results with a multicollision attack to generate a preimage of the hash function output. Fourthly, we investigate Streebog in the context of malicious hashing and by utilizing a carefully tailored differential path, we present a backdoored version of the hash function where collisions can be generated with practical complexity. Lastly, we propose a fault analysis attack which retrieves the inputs of the compression function and utilize it to recover the secret key when Streebog is used in the keyed simple prefix and secret-IV MACs, HMAC, or NMAC. All the presented results are on reduced round variants of the function except for our analysis of the malicious version of Streebog and our fault analysis attack where both attacks cover the full round hash function. Next, we examine the preimage resistance of the AES-based Maelstrom-0 hash function which is designed to be a lightweight alternative to the ISO standardized hash function Whirlpool. One of the distinguishing features of the Maelstrom-0 design is the proposal of a new chaining construction called 3CM which is based on the 3C/3C+ family. In our analysis, we employ a 4-stage approach that uses a modified technique to defeat the 3CM chaining construction and generates preimages of the 6-round reduced Maelstrom-0 hash function. Finally, we provide a key recovery attack on the new Russian encryption standard GOST R 34.12- 2015, also known as Kuznyechik. Although Kuznyechik adopts an AES-based design, it exhibits a faster diffusion rate as it employs an optimal diffusion transformation. In our analysis, we propose a meet-in-the-middle attack using the idea of efficient differential enumeration where we construct a three round distinguisher and consequently are able to recover 16-bytes of the master key of the reduced 5-round cipher. We also present partial sequence matching, by which we generate, store, and match parts of the compared parameters while maintaining negligible probability of matching error, thus the overall online time complexity of the attack is reduced