BLAKE及BLAKE2算法详解

1 简介

哈希算法 (Hash Algorithm) 是将任意长度的数据映射为固定长度数据的算法，也称为消息摘要。
一般情况下，哈希算法有两个特点：

1. 原始数据的细微变化（比如一个位翻转）会导致结果产生巨大差距
2. 运算过程不可逆，理论上无法从结果还原输入数据

因此，哈希算法主要用于数据完整性校验和加密/签名。而哈希算法的安全性就在于碰撞难易度，即已知结果，构建出具有相同结果的输入数据的难易度。

2 BLAKE

BLAKE算法于2008年提出，它包含两个版本，一种基于32位word用于产生最长256位的哈希结果，一种基于64位word用于产生最长512位的哈希结果，BLAKE算法核心操作是不断地将8个散列中间结果和16个输入word进行组合，从而产生下一轮组合的8个中间结果。按照最终截断的哈希长度，BLAKE-256和BLAKE-224使用32位字分别产生256位和224位的哈希结果（也称消息摘要），而BLAKE-512和BLAKE-384使用64位字并产生512位和384位哈希结果。算法核心变量如下：

 1 typedef struct
 2 {
 3   uint32_t h[8], s[4], t[2];
 4   int buflen, nullt;
 5   uint8_t  buf[64];
 6 } state256;
 7 
 8 typedef state256 state224;
 9 
10 typedef struct
11 {
12   uint64_t h[8], s[4], t[2];
13   int buflen, nullt;
14   uint8_t buf[128];
15 } state512;
16 
17 typedef state512 state384;
18 
19 const uint8_t sigma[][16] =
20 {
21   { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 },
22   {14, 10, 4, 8, 9, 15, 13, 6, 1, 12, 0, 2, 11, 7, 5, 3 },
23   {11, 8, 12, 0, 5, 2, 15, 13, 10, 14, 3, 6, 7, 1, 9, 4 },
24   { 7, 9, 3, 1, 13, 12, 11, 14, 2, 6, 5, 10, 4, 0, 15, 8 },
25   { 9, 0, 5, 7, 2, 4, 10, 15, 14, 1, 11, 12, 6, 8, 3, 13 },
26   { 2, 12, 6, 10, 0, 11, 8, 3, 4, 13, 7, 5, 15, 14, 1, 9 },
27   {12, 5, 1, 15, 14, 13, 4, 10, 0, 7, 6, 3, 9, 2, 8, 11 },
28   {13, 11, 7, 14, 12, 1, 3, 9, 5, 0, 15, 4, 8, 6, 2, 10 },
29   { 6, 15, 14, 9, 11, 3, 0, 8, 12, 2, 13, 7, 1, 4, 10, 5 },
30   {10, 2, 8, 4, 7, 6, 1, 5, 15, 11, 9, 14, 3, 12, 13 , 0 },
31   { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 },
32   {14, 10, 4, 8, 9, 15, 13, 6, 1, 12, 0, 2, 11, 7, 5, 3 },
33   {11, 8, 12, 0, 5, 2, 15, 13, 10, 14, 3, 6, 7, 1, 9, 4 },
34   { 7, 9, 3, 1, 13, 12, 11, 14, 2, 6, 5, 10, 4, 0, 15, 8 },
35   { 9, 0, 5, 7, 2, 4, 10, 15, 14, 1, 11, 12, 6, 8, 3, 13 },
36   { 2, 12, 6, 10, 0, 11, 8, 3, 4, 13, 7, 5, 15, 14, 1, 9 }
37 };
38 
39 const uint32_t u256[16] =
40 {
41   0x243f6a88, 0x85a308d3, 0x13198a2e, 0x03707344,
42   0xa4093822, 0x299f31d0, 0x082efa98, 0xec4e6c89,
43   0x452821e6, 0x38d01377, 0xbe5466cf, 0x34e90c6c,
44   0xc0ac29b7, 0xc97c50dd, 0x3f84d5b5, 0xb5470917
45 };
46 
47 const uint64_t u512[16] =
48 {
49   0x243f6a8885a308d3ULL, 0x13198a2e03707344ULL, 
50   0xa4093822299f31d0ULL, 0x082efa98ec4e6c89ULL,
51   0x452821e638d01377ULL, 0xbe5466cf34e90c6cULL, 
52   0xc0ac29b7c97c50ddULL, 0x3f84d5b5b5470917ULL,
53   0x9216d5d98979fb1bULL, 0xd1310ba698dfb5acULL, 
54   0x2ffd72dbd01adfb7ULL, 0xb8e1afed6a267e96ULL,
55   0xba7c9045f12c7f99ULL, 0x24a19947b3916cf7ULL, 
56   0x0801f2e2858efc16ULL, 0x636920d871574e69ULL
57 };
58 
59 
60 static const uint8_t padding[129] =
61 {
62   0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
63   0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
64   0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
65   0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
66   0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
67   0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
68   0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
69   0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
70 };

blake