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2019-07-21T04:08:24Z

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'''Streebog''' is a family of two hash functions, Streebog-256 and Streebog-512, that produce output 256-bit or 512-bit hash respectively from a bit string of arbitrary size using the [[Merkle–Damgård construction]]. The high-level structure of the new hash function resembles the one from GOST R 34.11-94, however, the compression function was changed significantly. The compression function operates in [[Miyaguchi–Preneel]] mode and employs a 12-round [[Advanced Encryption Standard|AES]]-like cipher.

The function was named '''Streebog''' after [[Stribog]], the god of rash wind in ancient Slavic mythology,

==Examples of Streebog hashes==
Hash values of empty string.
Streebog-256("")
0x 3f539a213e97c802cc229d474c6aa32a825a360b2a933a949fd925208d9ce1bb
Streebog-512("")
0x 8e945da209aa869f0455928529bcae4679e9873ab707b55315f56ceb98bef0a7 \
362f715528356ee83cda5f2aac4c6ad2ba3a715c1bcd81cb8e9f90bf4c1c1a8a

Even a small change in the message will (with overwhelming probability) result in a mostly different hash, due to the [[avalanche effect]]. For example, adding a period to the end of the sentence:
Streebog-256("[[The quick brown fox jumps over the lazy dog]]")
0x 3e7dea7f2384b6c5a3d0e24aaa29c05e89ddd762145030ec22c71a6db8b2c1f4
Streebog-256("[[The quick brown fox jumps over the lazy dog]].")
0x 36816a824dcbe7d6171aa58500741f2ea2757ae2e1784ab72c5c3c6c198d71da
Streebog-512("[[The quick brown fox jumps over the lazy dog]]")
0x d2b793a0bb6cb5904828b5b6dcfb443bb8f33efc06ad09368878ae4cdc8245b9 \
7e60802469bed1e7c21a64ff0b179a6a1e0bb74d92965450a0adab69162c00fe
Streebog-512("[[The quick brown fox jumps over the lazy dog]].")
0x fe0c42f267d921f940faa72bd9fcf84f9f1bd7e9d055e9816e4c2ace1ec83be8 \
2d2957cd59b86e123d8f5adee80b3ca08a017599a9fc1a14d940cf87c77df070

==Cryptanalysis==
In 2013 the Russian Technical Committee for Standardization "Cryptography and Security Mechanisms" (TC 26) with the participation of Academy of Cryptography of the Russian Federation declared an open competition for cryptanalysis of Streebog hash function, which attracted the international attention to the function.

Ma, ''et al'', describe a [[preimage attack]] that takes 2496 time and 264 memory or 2504 time and 211 memory to find a single preimage of GOST-512 reduced to 6 rounds. They also describe a [[collision attack]] with 2181 [[time complexity]] and 264 memory requirement in the same paper.

Guo, ''et al'', describe a [[second preimage attack]] on full Streebog-512 with total time complexity equivalent to 2266 compression function evaluations, if the message has more than 2259 blocks.

AlTawy and Youssef published an attack to a modified version of Streebog with different round constants. While this attack may not have a direct impact on the security of the original Streebog hash function, it raised a question about the origin of the used parameters in the function. The designers published a paper explaining that these are pseudorandom constants generated with Streebog-like hash function, provided with 12 different natural language input messages.

AlTawy, ''et al'', found 5-round free-start collision and a 7.75 free-start near collision for the internal cipher with complexities 28 and 240, respectively, as well as attacks on the compression function with 7.75 round semi free-start collision with time complexity 2184 and memory complexity 28, 8.75 and 9.75 round semi free-start near collisions with time complexities 2120 and 2196, respectively.

Wang, ''et al'', describe a collision attack on the compression function reduced to 9.5 rounds with 2176 time complexity and 2128 memory complexity.

== See also ==
* [[Hash function security summary]]

==Source==

[http://wikipedia.org/ http://wikipedia.org/]

[[Category:Cryptography]]
[[Category:Cryptographic algorithms]]

Streebog - Revision history

Admin: Created page with "'''Streebog''' is a family of two hash functions, Streebog-256 and Streebog-512, that produce output 256-bit or 512-bit hash respectively from a bit string of arbitrary size u..."