Rebound attacks on stribog

Abstract. In August 2012, the Stribog hash function was selected as the new Russian 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. In this paper we investigate the collision resistance of the Stribog compression function and its internal cipher. Specifically, we present a message differential path for the internal block cipher that allows us to efficiently obtain a 5-round free-start collision and a 7.75 free-start near collision for the internal cipher with complexities 2 8 and 2 40 , respectively. Finally, the compression function is analyzed and a 7.75 round semi freestart collision, 8.75 and 9.75 round semi free-start near collisions are presented along with an example for 4.75 round 50 out of 64 bytes near colliding message pair

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

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

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

Streebog compression function as PRF in secret-key settings

Security of the many keyed hash-based cryptographic constructions (such as HMAC) depends on the fact that the underlying compression function $g(H,M)$ is a pseudorandom function (PRF). This paper presents key-recovery algorithms for 7 rounds (of 12) of Streebog compression function. Two cases were considered, as a secret key can be used: the previous state $H$ or the message block $M$. The proposed methods implicitly show that Streebog compression function has a large security margin as PRF in the above-mentioned secret-key settings

Related-key attacks on the compression function of Streebog

Related-key attacks against block ciphers are often considered unrealistic. In practice, as far as possible, the existence of a known relation between the secret encryption keys is avoided. Despite this, related keys arise directly in some widely used keyed hash functions. This is especially true for HMAC-Streebog, where known constants and manipulated parameters are added to the secret key. The relation is determined by addition modulo $2$ and $2^{n}$. The security of HMAC reduces to the properties of the underlying compression function. Therefore, as an initial analysis we propose key-recovery methods for 10 and 11 rounds (out of 12) of Streebog compression function in the related-key setting. The result shows that Streebog successfully resists attacks even in the model with such powerful adversaries

Keyed Streebog is a secure PRF and MAC

One of the most popular ways to turn a keyless hash function into a keyed one is the HMAC algorithm. This approach is too expensive in some cases due to double hashing. Excessive overhead can sometimes be avoided by using certain features of the hash function itself. The paper presents a simple and safe way to create a keyed cryptoalgorithm (conventionally called Streebog-K ) from hash function Streebog $\mathsf{H}(M)$. Let $K$ be a secret key, then $\mathsf{KH}(K,M)=\mathsf{H}(K||M)$ is a secure pseudorandom function (PRF) and, therefore, a good message authentification code (MAC). The proof is obtained by reduction of the security of the presented construction to the resistance of the underlying compression function to the related key attacks (PRF-RKA). The security bounds of Streebog-K are essentially the same as those of HMAC-Streebog, but the computing speed doubles when short messages are used

The Usage of Counter Revisited: Second-Preimage Attack on New Russian Standardized Hash Function

International audienceStreebog is a new Russian hash function standard. It follows the HAIFA framework as domain extension algorithm and claims to resist recent generic second-preimage attacks with long messages. However, we demonstrate in this article that the specific instantiation of the HAIFA framework used in Streebog makes it weak against such attacks. More precisely, we observe that Streebog makes a rather poor usage of the HAIFA counter input in the compression function, which allows to con-struct second-preimages on the full Streebog-512 with a complexity as low as n × 2 n/2 (namely 2 266) compression function evaluations for long messages. This complexity has to be compared with the expected 2 512 computations bound that an ideal hash function should provide. Our work is a good example that one must be careful when using a design framework for which not all instances are secure. HAIFA helps designers to build a secure hash function, but one should pay attention to the way the counter is handled inside the compression function

About “kk-bit security” of MACs based on hash function Streebog

Various message authentication codes (MACs), including HMAC-Streebog and Streebog-K, are based on the keyless hash function Streebog. Under the assumption that the compression function of Streebog is resistant to the related key attacks, the security proofs of these algorithms were recently presented at CTCrypt 2022. We carefully detail the resources of the adversary in the related key settings, revisit the proof, and obtain tight security bounds. Let $n$ be the bit length of the hash function state. If the amount of processed data is less than about $2^{n-k}$ blocks, then for HMAC-Streebog-512 and Streebog-K, the only effective method of forgery (or distinguishing) is guessing the $k$-bit secret key or the tag if it is shorter than the key. So, we can speak about ``$k$-bit security\u27\u27 without specifying the amount of material, if the key length is no longer than half of a state. The bound for HMAC-Streebog-256 is worse and equal to $2^{\frac{n}{2}-k}$ blocks

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}