Code:
/ FX-1434 / FX-1434 / 1.0 / untmp / whidbey / REDBITS / ndp / clr / src / BCL / System / Security / Cryptography / SHA256Managed.cs / 1 / SHA256Managed.cs
// ==++== // // Copyright (c) Microsoft Corporation. All rights reserved. // // ==--== // // SHA256Managed.cs // // C# implementation of the proposed SHA-256 hash algorithm // namespace System.Security.Cryptography { using System; [System.Runtime.InteropServices.ComVisible(true)] public class SHA256Managed : SHA256 { private byte[] _buffer; private long _count; // Number of bytes in the hashed message private UInt32[] _stateSHA256; private UInt32[] _W; // // public constructors // public SHA256Managed() { if (Utils.FipsAlgorithmPolicy == 1) throw new InvalidOperationException(Environment.GetResourceString("Cryptography_NonCompliantFIPSAlgorithm")); _stateSHA256 = new UInt32[8]; _buffer = new byte[64]; _W = new UInt32[64]; InitializeState(); } // // public methods // public override void Initialize() { InitializeState(); // Zeroize potentially sensitive information. Array.Clear(_buffer, 0, _buffer.Length); Array.Clear(_W, 0, _W.Length); } protected override void HashCore(byte[] rgb, int ibStart, int cbSize) { _HashData(rgb, ibStart, cbSize); } protected override byte[] HashFinal() { return _EndHash(); } // // private methods // private void InitializeState() { _count = 0; _stateSHA256[0] = 0x6a09e667; _stateSHA256[1] = 0xbb67ae85; _stateSHA256[2] = 0x3c6ef372; _stateSHA256[3] = 0xa54ff53a; _stateSHA256[4] = 0x510e527f; _stateSHA256[5] = 0x9b05688c; _stateSHA256[6] = 0x1f83d9ab; _stateSHA256[7] = 0x5be0cd19; } /* SHA256 block update operation. Continues an SHA message-digest operation, processing another message block, and updating the context. */ private unsafe void _HashData(byte[] partIn, int ibStart, int cbSize) { int bufferLen; int partInLen = cbSize; int partInBase = ibStart; /* Compute length of buffer */ bufferLen = (int) (_count & 0x3f); /* Update number of bytes */ _count += partInLen; fixed (uint* stateSHA256 = _stateSHA256) { fixed (byte* buffer = _buffer) { fixed (uint* expandedBuffer = _W) { if ((bufferLen > 0) && (bufferLen + partInLen >= 64)) { Buffer.InternalBlockCopy(partIn, partInBase, _buffer, bufferLen, 64 - bufferLen); partInBase += (64 - bufferLen); partInLen -= (64 - bufferLen); SHATransform(expandedBuffer, stateSHA256, buffer); bufferLen = 0; } /* Copy input to temporary buffer and hash */ while (partInLen >= 64) { Buffer.InternalBlockCopy(partIn, partInBase, _buffer, 0, 64); partInBase += 64; partInLen -= 64; SHATransform(expandedBuffer, stateSHA256, buffer); } if (partInLen > 0) { Buffer.InternalBlockCopy(partIn, partInBase, _buffer, bufferLen, partInLen); } } } } } /* SHA256 finalization. Ends an SHA256 message-digest operation, writing the message digest. */ private byte[] _EndHash() { byte[] pad; int padLen; long bitCount; byte[] hash = new byte[32]; // HashSizeValue = 256 /* Compute padding: 80 00 00 ... 00 00*/ padLen = 64 - (int)(_count & 0x3f); if (padLen <= 8) padLen += 64; pad = new byte[padLen]; pad[0] = 0x80; // Convert count to bit count bitCount = _count * 8; pad[padLen-8] = (byte) ((bitCount >> 56) & 0xff); pad[padLen-7] = (byte) ((bitCount >> 48) & 0xff); pad[padLen-6] = (byte) ((bitCount >> 40) & 0xff); pad[padLen-5] = (byte) ((bitCount >> 32) & 0xff); pad[padLen-4] = (byte) ((bitCount >> 24) & 0xff); pad[padLen-3] = (byte) ((bitCount >> 16) & 0xff); pad[padLen-2] = (byte) ((bitCount >> 8) & 0xff); pad[padLen-1] = (byte) ((bitCount >> 0) & 0xff); /* Digest padding */ _HashData(pad, 0, pad.Length); /* Store digest */ Utils.DWORDToBigEndian (hash, _stateSHA256, 8); HashValue = hash; return hash; } private readonly static UInt32[] _K = { 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 }; private static unsafe void SHATransform (uint* expandedBuffer, uint* state, byte* block) { UInt32 a, b, c, d, e, f, h, g; UInt32 aa, bb, cc, dd, ee, ff, hh, gg; UInt32 T1; a = state[0]; b = state[1]; c = state[2]; d = state[3]; e = state[4]; f = state[5]; g = state[6]; h = state[7]; // fill in the first 16 bytes of W. Utils.DWORDFromBigEndian(expandedBuffer, 16, block); SHA256Expand(expandedBuffer); /* Apply the SHA256 compression function */ // We are trying to be smart here and avoid as many copies as we can // The perf gain with this method over the straightforward modify and shift // forward is >= 20%, so it's worth the pain for (int j=0; j<64; ) { T1 = h + Sigma_1(e) + Ch(e,f,g) + _K[j] + expandedBuffer[j]; ee = d + T1; aa = T1 + Sigma_0(a) + Maj(a,b,c); j++; T1 = g + Sigma_1(ee) + Ch(ee,e,f) + _K[j] + expandedBuffer[j]; ff = c + T1; bb = T1 + Sigma_0(aa) + Maj(aa,a,b); j++; T1 = f + Sigma_1(ff) + Ch(ff,ee,e) + _K[j] + expandedBuffer[j]; gg = b + T1; cc = T1 + Sigma_0(bb) + Maj(bb,aa,a); j++; T1 = e + Sigma_1(gg) + Ch(gg,ff,ee) + _K[j] + expandedBuffer[j]; hh = a + T1; dd = T1 + Sigma_0(cc) + Maj(cc,bb,aa); j++; T1 = ee + Sigma_1(hh) + Ch(hh,gg,ff) + _K[j] + expandedBuffer[j]; h = aa + T1; d = T1 + Sigma_0(dd) + Maj(dd,cc,bb); j++; T1 = ff + Sigma_1(h) + Ch(h,hh,gg) + _K[j] + expandedBuffer[j]; g = bb + T1; c = T1 + Sigma_0(d) + Maj(d,dd,cc); j++; T1 = gg + Sigma_1(g) + Ch(g,h,hh) + _K[j] + expandedBuffer[j]; f = cc + T1; b = T1 + Sigma_0(c) + Maj(c,d,dd); j++; T1 = hh + Sigma_1(f) + Ch(f,g,h) + _K[j] + expandedBuffer[j]; e = dd + T1; a = T1 + Sigma_0(b) + Maj(b,c,d); j++; } state[0] += a; state[1] += b; state[2] += c; state[3] += d; state[4] += e; state[5] += f; state[6] += g; state[7] += h; } private static UInt32 RotateRight(UInt32 x, int n) { return (((x) >> (n)) | ((x) << (32-(n)))); } private static UInt32 Ch(UInt32 x, UInt32 y, UInt32 z) { return ((x & y) ^ ((x ^ 0xffffffff) & z)); } private static UInt32 Maj(UInt32 x, UInt32 y, UInt32 z) { return ((x & y) ^ (x & z) ^ (y & z)); } private static UInt32 sigma_0(UInt32 x) { return (RotateRight(x,7) ^ RotateRight(x,18) ^ (x >> 3)); } private static UInt32 sigma_1(UInt32 x) { return (RotateRight(x,17) ^ RotateRight(x,19) ^ (x >> 10)); } private static UInt32 Sigma_0(UInt32 x) { return (RotateRight(x,2) ^ RotateRight(x,13) ^ RotateRight(x,22)); } private static UInt32 Sigma_1(UInt32 x) { return (RotateRight(x,6) ^ RotateRight(x,11) ^ RotateRight(x,25)); } /* This function creates W_16,...,W_63 according to the formula W_j <- sigma_1(W_{j-2}) + W_{j-7} + sigma_0(W_{j-15}) + W_{j-16}; */ private static unsafe void SHA256Expand (uint* x) { for (int i = 16; i < 64; i++) { x[i] = sigma_1(x[i-2]) + x[i-7] + sigma_0(x[i-15]) + x[i-16]; } } } }
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