| // Copyright (c) 2012, the Dart project authors. Please see the AUTHORS file |
| // for details. All rights reserved. Use of this source code is governed by a |
| // BSD-style license that can be found in the LICENSE file. |
| |
| library crypto.sha256; |
| |
| import 'dart:typed_data'; |
| |
| import 'hash.dart'; |
| import 'hash_base.dart'; |
| import 'utils.dart'; |
| |
| /// An implementation of the [SHA-256][rfc] hash function. |
| /// |
| /// [rfc]: http://tools.ietf.org/html/rfc6234 |
| abstract class SHA256 implements Hash { |
| factory SHA256() = _SHA256; |
| |
| SHA256 newInstance(); |
| } |
| |
| /// Data from a non-linear function that functions as reproducible noise. |
| const List<int> _noise = const [ |
| 0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5, 0x3956c25b, 0x59f111f1, |
| 0x923f82a4, 0xab1c5ed5, 0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3, |
| 0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174, 0xe49b69c1, 0xefbe4786, |
| 0x0fc19dc6, 0x240ca1cc, 0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da, |
| 0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7, 0xc6e00bf3, 0xd5a79147, |
| 0x06ca6351, 0x14292967, 0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13, |
| 0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85, 0xa2bfe8a1, 0xa81a664b, |
| 0xc24b8b70, 0xc76c51a3, 0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070, |
| 0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5, 0x391c0cb3, 0x4ed8aa4a, |
| 0x5b9cca4f, 0x682e6ff3, 0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208, |
| 0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2 |
| ]; |
| |
| /// The concrete implementation of [SHA256]. |
| /// |
| /// This is separate so that it can extend [HashBase] without leaking additional |
| /// public memebers. |
| class _SHA256 extends HashBase implements SHA256 { |
| final digest = new Uint32List(8); |
| |
| /// The sixteen words from the original chunk, extended to 64 words. |
| /// |
| /// This is an instance variable to avoid re-allocating, but its data isn't |
| /// used across invocations of [updateHash]. |
| final Uint32List _extended; |
| |
| _SHA256() |
| : _extended = new Uint32List(64), |
| super(16) { |
| // Initial value of the hash parts. First 32 bits of the fractional parts |
| // of the square roots of the first 8 prime numbers. |
| digest[0] = 0x6a09e667; |
| digest[1] = 0xbb67ae85; |
| digest[2] = 0x3c6ef372; |
| digest[3] = 0xa54ff53a; |
| digest[4] = 0x510e527f; |
| digest[5] = 0x9b05688c; |
| digest[6] = 0x1f83d9ab; |
| digest[7] = 0x5be0cd19; |
| } |
| |
| SHA256 newInstance() => new _SHA256(); |
| |
| // The following helper functions are taken directly from |
| // http://tools.ietf.org/html/rfc6234. |
| |
| _rotr32(int n, int x) => (x >> n) | ((x << (32 - n)) & mask32); |
| _ch(int x, int y, int z) => (x & y) ^ ((~x & mask32) & z); |
| _maj(int x, int y, int z) => (x & y) ^ (x & z) ^ (y & z); |
| _bsig0(int x) => _rotr32(2, x) ^ _rotr32(13, x) ^ _rotr32(22, x); |
| _bsig1(int x) => _rotr32(6, x) ^ _rotr32(11, x) ^ _rotr32(25, x); |
| _ssig0(int x) => _rotr32(7, x) ^ _rotr32(18, x) ^ (x >> 3); |
| _ssig1(int x) => _rotr32(17, x) ^ _rotr32(19, x) ^ (x >> 10); |
| |
| void updateHash(Uint32List chunk) { |
| assert(chunk.length == 16); |
| |
| // Prepare message schedule. |
| for (var i = 0; i < 16; i++) { |
| _extended[i] = chunk[i]; |
| } |
| for (var i = 16; i < 64; i++) { |
| _extended[i] = add32( |
| add32(_ssig1(_extended[i - 2]), _extended[i - 7]), |
| add32(_ssig0(_extended[i - 15]), _extended[i - 16])); |
| } |
| |
| // Shuffle around the bits. |
| var a = digest[0]; |
| var b = digest[1]; |
| var c = digest[2]; |
| var d = digest[3]; |
| var e = digest[4]; |
| var f = digest[5]; |
| var g = digest[6]; |
| var h = digest[7]; |
| |
| for (var i = 0; i < 64; i++) { |
| var temp1 = add32( |
| add32(h, _bsig1(e)), |
| add32( |
| _ch(e, f, g), |
| add32(_noise[i], _extended[i]))); |
| var temp2 = add32(_bsig0(a), _maj(a, b, c)); |
| h = g; |
| g = f; |
| f = e; |
| e = add32(d, temp1); |
| d = c; |
| c = b; |
| b = a; |
| a = add32(temp1, temp2); |
| } |
| |
| // Update hash values after iteration. |
| digest[0] = add32(a, digest[0]); |
| digest[1] = add32(b, digest[1]); |
| digest[2] = add32(c, digest[2]); |
| digest[3] = add32(d, digest[3]); |
| digest[4] = add32(e, digest[4]); |
| digest[5] = add32(f, digest[5]); |
| digest[6] = add32(g, digest[6]); |
| digest[7] = add32(h, digest[7]); |
| } |
| } |