[PATCH 0/5] GOST 28147-89 support

GOST 28147-89 is the data encryption standard for Russia (old, but still used). English translation is provided in RFC 5830. It defines a 64-bit cipher, ECB, CFB and counter (CNT) modes on top of it and a special mode of basic transformation that is used for MAC construction called "Imitovstavka" (IMIT).

For GOST 28147-89 several S-boxes are defined (standard itself has defined "test" S-box, another "test" S-box is defined in GOST R 34.11-94 (RFC 5831), RFC 4357 defines several CryptoPro S-Boxes and finally TC26 has defined TC26-Z S-Box (RFC 7836)).

Before finalizing documentation I'd like to hear your opinion on the GOST 28147-89 cipher and MAC interface.