The many faces of GOST R 34.11-94
I somehow prepared tests for a system, one of the modules of which, among other things, calculated the value of the hash function for the downloaded file. The necessary algorithm was also specified in the statement of work - GOST R 34.11-94. As a standard, I took the value of the hash calculated by the third-party utility Rhash .
f86c9ecfb6e63726b35ebc79528d013d52b781e06e29d7eb0c9d1cb256efb7c1Realizing that the function is calculated by the standard library, I sent a request to clean up my conscience that corresponds to loading the file into the module. But the fate of man is full of surprises. And you just have to relax, as you see something like this:
964ba8755ca782ec3c5e0f98c93347f9b96d9f39cf5c7fdef43a23273fe8868aWho is wrong - the developer of the module or utility?
It turned out neither one nor the other.
The fact is that GOST R 34.11-94 implies the use of parameters - the so-called replacement nodes and the starting hash vector. But it does not regulate specific values. Nevertheless, in the appendix to GOST there are examples of these values and a recommendation:
Use only in test cases for this standard.
After studying the subject area, it turned out that there are two RFCs. RFC 4357 , which uses the parameters created by CryptoPro, and RFC 5831 with the same values from GOST. Rhash by default considers a hash according to RFC 5831. The use of CryptoPro parameters must be explicitly specified: It would seem that the problem has been solved. But to make it even more interesting, the standard does not define a hash output format. And so the question is with byte order . For the uninitiated, there are two main ways of presenting data. From high byte to low (Big-endian), and vice versa (Little-endian). Consider an example. For clarity, bytes are highlighted. Big-endian byte order: Little-endian order:
rhash --gost-cryptopro <Имя файла>
rhash --gost-cryptopro --gost-reverse <Имя файла>
8a86e83f27233af4de7f5ccf399f6db9f94733c9980f5e3cec82a75c75a84b96rhash --gost-cryptopro <Имя файла>
964ba8755ca782ec3c5e0f98c93347f9b96d9f39cf5c7fdef43a23273fe8868aThus, there is no contradiction - all of the above values, and also comply with GOST R 34.11-94. Links: Wikipedia Detailed Description
rhash --gost --gost-reverse <Имя файла>
c1b7ef56b21c9d0cebd7296ee081b7523d018d5279bc5eb32637e6b6cf9e6cf8
