kuznechik 0.1.1

# Synchronous encryption algorithm "Kuznechik" (GOST R 34.12-2015, GOST R 34.13-2015)

Implementation of the block synchronous encryption algorithm "Kuznechik" in Rust lang.

## Encryption modes

| Struct |            Title            | Reduction |
|:------:|:--------------------------- |:---------:|
| AlgEcb | Electronic Codebook         |    ЕСВ    |
| AlgCtr | Counter                     |    CTR    |
| AlgOfb | Output Feedback             |    OFB    |
| AlgCbc | Cipher Block Chaining       |    СВС    |
| AlgCfb | Cipher Feedback             |    CFB    |
| AlgMac | Message Authentication Code |    MAC    |

# Usage (AlgOfb):
The following example encrypts and decrypts a 64-byte data block `data` using the OFB method. Encryption by other methods is similar, in some the gamma is not required (more details in [tests.rs](https://github.com/DmitryNX/Kuznechik/blob/master/src/tests.rs)).

```
extern crate kuznechik;

use self::kuznechik::{Kuznechik, Algorithm, AlgOfb};

fn main() {
    // Initialization
    let gamma = vec![0x12, 0x34, 0x56, 0x78, 0x90, 0xab, 0xce, 0xf0, 0xa1, 0xb2, 0xc3, 0xd4, 0xe5, 0xf0, 0x01, 0x12,
                     0x23, 0x34, 0x45, 0x56, 0x67, 0x78, 0x89, 0x90, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19];

    let master_key = [0x88, 0x99, 0xaa, 0xbb, 0xcc, 0xdd, 0xee, 0xff, 0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77,
        0xfe, 0xdc, 0xba, 0x98, 0x76, 0x54, 0x32, 0x10, 0x01, 0x23, 0x45, 0x67, 0x89, 0xab, 0xcd, 0xef];

    let kuz = Kuznechik::new_with_master_key(master_key);
    let mut alg = AlgOfb::new(&kuz);
    alg.gamma = gamma.clone();

    let data = vec![0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77, 0x00, 0xff, 0xee, 0xdd, 0xcc, 0xbb, 0xaa, 0x99, 0x88,
                    0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77, 0x88, 0x99, 0xaa, 0xbb, 0xcc, 0xee, 0xff, 0x0a,
                    0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77, 0x88, 0x99, 0xaa, 0xbb, 0xcc, 0xee, 0xff, 0x0a, 0x00,
                    0x22, 0x33, 0x44, 0x55, 0x66, 0x77, 0x88, 0x99, 0xaa, 0xbb, 0xcc, 0xee, 0xff, 0x0a, 0x00, 0x11];

    // Encryption
    let enc_data = alg.encrypt(data.clone());

    assert_eq!(enc_data, vec![0x81, 0x80, 0x0a, 0x59, 0xb1, 0x84, 0x2b, 0x24, 0xff, 0x1f, 0x79, 0x5e, 0x89, 0x7a, 0xbd, 0x95,
                              0xed, 0x5b, 0x47, 0xa7, 0x04, 0x8c, 0xfa, 0xb4, 0x8f, 0xb5, 0x21, 0x36, 0x9d, 0x93, 0x26, 0xbf,
                              0x66, 0xa2, 0x57, 0xac, 0x3c, 0xa0, 0xb8, 0xb1, 0xc8, 0x0f, 0xe7, 0xfc, 0x10, 0x28, 0x8a, 0x13,
                              0x20, 0x3e, 0xbb, 0xc0, 0x66, 0x13, 0x86, 0x60, 0xa0, 0x29, 0x22, 0x43, 0xf6, 0x90, 0x31, 0x50]);

    // Decryption
    alg.gamma = gamma;
    let dec_data = alg.decrypt(enc_data);

    assert_eq!(dec_data, data);
}
```