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1 // Copyright (c) 2012, the Dart project authors. Please see the AUTHORS file | |
2 // for details. All rights reserved. Use of this source code is governed by a | |
3 // BSD-style license that can be found in the LICENSE file. | |
4 | |
5 part of dart.crypto; | |
6 | |
7 // The SHA256 hasher is used to compute an SHA256 message digest. | |
8 class _SHA256 extends _HashBase implements SHA256 { | |
9 // Construct a SHA256 hasher object. | |
10 _SHA256() : _w = new List(64), super(16, 8, true) { | |
11 // Initial value of the hash parts. First 32 bits of the fractional parts | |
12 // of the square roots of the first 8 prime numbers. | |
13 _h[0] = 0x6a09e667; | |
14 _h[1] = 0xbb67ae85; | |
15 _h[2] = 0x3c6ef372; | |
16 _h[3] = 0xa54ff53a; | |
17 _h[4] = 0x510e527f; | |
18 _h[5] = 0x9b05688c; | |
19 _h[6] = 0x1f83d9ab; | |
20 _h[7] = 0x5be0cd19; | |
21 } | |
22 | |
23 // Returns a new instance of this Hash. | |
24 SHA256 newInstance() { | |
25 return new SHA256(); | |
26 } | |
27 | |
28 // Table of round constants. First 32 bits of the fractional | |
29 // parts of the cube roots of the first 64 prime numbers. | |
30 static const List<int> _K = | |
31 const [ 0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5, 0x3956c25b, | |
32 0x59f111f1, 0x923f82a4, 0xab1c5ed5, 0xd807aa98, 0x12835b01, | |
33 0x243185be, 0x550c7dc3, 0x72be5d74, 0x80deb1fe, 0x9bdc06a7, | |
34 0xc19bf174, 0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc, | |
35 0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da, 0x983e5152, | |
36 0xa831c66d, 0xb00327c8, 0xbf597fc7, 0xc6e00bf3, 0xd5a79147, | |
37 0x06ca6351, 0x14292967, 0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, | |
38 0x53380d13, 0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85, | |
39 0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3, 0xd192e819, | |
40 0xd6990624, 0xf40e3585, 0x106aa070, 0x19a4c116, 0x1e376c08, | |
41 0x2748774c, 0x34b0bcb5, 0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, | |
42 0x682e6ff3, 0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208, | |
43 0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2 ]; | |
44 | |
45 // Helper functions as defined in http://tools.ietf.org/html/rfc6234 | |
46 _rotr32(n, x) => (x >> n) | ((x << (32 - n)) & _MASK_32); | |
47 _ch(x, y, z) => (x & y) ^ ((~x & _MASK_32) & z); | |
48 _maj(x, y, z) => (x & y) ^ (x & z) ^ (y & z); | |
49 _bsig0(x) => _rotr32(2, x) ^ _rotr32(13, x) ^ _rotr32(22, x); | |
50 _bsig1(x) => _rotr32(6, x) ^ _rotr32(11, x) ^ _rotr32(25, x); | |
51 _ssig0(x) => _rotr32(7, x) ^ _rotr32(18, x) ^ (x >> 3); | |
52 _ssig1(x) => _rotr32(17, x) ^ _rotr32(19, x) ^ (x >> 10); | |
53 | |
54 // Compute one iteration of the SHA256 algorithm with a chunk of | |
55 // 16 32-bit pieces. | |
56 void _updateHash(List<int> M) { | |
57 assert(M.length == 16); | |
58 | |
59 // Prepare message schedule. | |
60 var i = 0; | |
61 for (; i < 16; i++) { | |
62 _w[i] = M[i]; | |
63 } | |
64 for (; i < 64; i++) { | |
65 _w[i] = _add32(_add32(_ssig1(_w[i - 2]), _w[i - 7]), | |
66 _add32(_ssig0(_w[i - 15]), _w[i - 16])); | |
67 } | |
68 | |
69 // Shuffle around the bits. | |
70 var a = _h[0]; | |
71 var b = _h[1]; | |
72 var c = _h[2]; | |
73 var d = _h[3]; | |
74 var e = _h[4]; | |
75 var f = _h[5]; | |
76 var g = _h[6]; | |
77 var h = _h[7]; | |
78 | |
79 for (var t = 0; t < 64; t++) { | |
80 var t1 = _add32(_add32(h, _bsig1(e)), | |
81 _add32(_ch(e, f, g), _add32(_K[t], _w[t]))); | |
82 var t2 = _add32(_bsig0(a), _maj(a, b, c)); | |
83 h = g; | |
84 g = f; | |
85 f = e; | |
86 e = _add32(d, t1); | |
87 d = c; | |
88 c = b; | |
89 b = a; | |
90 a = _add32(t1, t2); | |
91 } | |
92 | |
93 // Update hash values after iteration. | |
94 _h[0] = _add32(a, _h[0]); | |
95 _h[1] = _add32(b, _h[1]); | |
96 _h[2] = _add32(c, _h[2]); | |
97 _h[3] = _add32(d, _h[3]); | |
98 _h[4] = _add32(e, _h[4]); | |
99 _h[5] = _add32(f, _h[5]); | |
100 _h[6] = _add32(g, _h[6]); | |
101 _h[7] = _add32(h, _h[7]); | |
102 } | |
103 | |
104 List<int> _w; | |
105 } | |
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