class/corlib/System.Security.Cryptography/SHA256Managed.cs

   1 //
   2 // System.Security.Cryptography.SHA256Managed.cs
   3 //
   4 // Author:
   5 //   Matthew S. Ford (Matthew.S.Ford@Rose-Hulman.Edu)
   6 //
   7 // (C) 2001
   8 // Copyright (C) 2004, 2005 Novell, Inc (http://www.novell.com)
   9 //
  10 // Permission is hereby granted, free of charge, to any person obtaining
  11 // a copy of this software and associated documentation files (the
  12 // "Software"), to deal in the Software without restriction, including
  13 // without limitation the rights to use, copy, modify, merge, publish,
  14 // distribute, sublicense, and/or sell copies of the Software, and to
  15 // permit persons to whom the Software is furnished to do so, subject to
  16 // the following conditions:
  17 //
  18 // The above copyright notice and this permission notice shall be
  19 // included in all copies or substantial portions of the Software.
  20 //
  21 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  22 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  23 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  24 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  25 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  26 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  27 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  28 //
  29
  30 using System.Runtime.InteropServices;
  31
  32 namespace System.Security.Cryptography {
  33
  34         [ComVisible (true)]
  35         public class SHA256Managed : SHA256 {
  36
  37                 private const int BLOCK_SIZE_BYTES =  64;
  38                 private uint[] _H;
  39                 private ulong count;
  40                 private byte[] _ProcessingBuffer;   // Used to start data when passed less than a block worth.
  41                 private int _ProcessingBufferCount; // Counts how much data we have stored that still needs processed.
  42                 private uint[] buff;
  43
  44                 public SHA256Managed ()
  45                 {
  46                         _H = new uint [8];
  47                         _ProcessingBuffer = new byte [BLOCK_SIZE_BYTES];
  48                         buff = new uint[64];
  49                         Initialize ();
  50                 }
  51
  52                 protected override void HashCore (byte[] rgb, int ibStart, int cbSize)
  53                 {
  54                         int i;
  55                         State = 1;
  56
  57                         if (_ProcessingBufferCount != 0) {
  58                                 if (cbSize < (BLOCK_SIZE_BYTES - _ProcessingBufferCount)) {
  59                                         System.Buffer.BlockCopy (rgb, ibStart, _ProcessingBuffer, _ProcessingBufferCount, cbSize);
  60                                         _ProcessingBufferCount += cbSize;
  61                                         return;
  62                                 }
  63                                 else {
  64                                         i = (BLOCK_SIZE_BYTES - _ProcessingBufferCount);
  65                                         System.Buffer.BlockCopy (rgb, ibStart, _ProcessingBuffer, _ProcessingBufferCount, i);
  66                                         ProcessBlock (_ProcessingBuffer, 0);
  67                                         _ProcessingBufferCount = 0;
  68                                         ibStart += i;
  69                                         cbSize -= i;
  70                                 }
  71                         }
  72
  73                         for (i = 0; i < cbSize - cbSize % BLOCK_SIZE_BYTES; i += BLOCK_SIZE_BYTES) {
  74                                 ProcessBlock (rgb, ibStart + i);
  75                         }
  76
  77                         if (cbSize % BLOCK_SIZE_BYTES != 0) {
  78                                 System.Buffer.BlockCopy (rgb, cbSize - cbSize % BLOCK_SIZE_BYTES + ibStart, _ProcessingBuffer, 0, cbSize % BLOCK_SIZE_BYTES);
  79                                 _ProcessingBufferCount = cbSize % BLOCK_SIZE_BYTES;
  80                         }
  81                 }
  82
  83                 protected override byte[] HashFinal ()
  84                 {
  85                         byte[] hash = new byte[32];
  86                         int i, j;
  87
  88                         ProcessFinalBlock (_ProcessingBuffer, 0, _ProcessingBufferCount);
  89
  90                         for (i=0; i<8; i++) {
  91                                 for (j=0; j<4; j++) {
  92                                         hash[i*4+j] = (byte)(_H[i] >> (24-j*8));
  93                                 }
  94                         }
  95
  96                         State = 0;
  97                         return hash;
  98                 }
  99
 100                 public override void Initialize ()
 101                 {
 102                         count = 0;
 103                         _ProcessingBufferCount = 0;
 104
 105                         _H[0] = 0x6A09E667;
 106                         _H[1] = 0xBB67AE85;
 107                         _H[2] = 0x3C6EF372;
 108                         _H[3] = 0xA54FF53A;
 109                         _H[4] = 0x510E527F;
 110                         _H[5] = 0x9B05688C;
 111                         _H[6] = 0x1F83D9AB;
 112                         _H[7] = 0x5BE0CD19;
 113                 }
 114
 115                 private void ProcessBlock (byte[] inputBuffer, int inputOffset)
 116                 {
 117                         uint a, b, c, d, e, f, g, h;
 118                         uint t1, t2;
 119                         int i;
 120                         uint[] K1 = SHAConstants.K1;
 121                         uint[] buff = this.buff;
 122
 123                         count += BLOCK_SIZE_BYTES;
 124
 125                         for (i=0; i<16; i++) {
 126                                 buff[i] = (uint)(((inputBuffer[inputOffset + 4 * i]) << 24)
 127                                         | ((inputBuffer[inputOffset + 4 * i + 1]) << 16)
 128                                         | ((inputBuffer[inputOffset + 4 * i + 2]) << 8)
 129                                         | ((inputBuffer[inputOffset + 4 * i + 3])));
 130                         }
 131
 132
 133                         for (i=16; i<64; i++) {
 134                                 t1 = buff[i - 15];
 135                                 t1 = (((t1 >> 7) | (t1 << 25)) ^ ((t1 >> 18) | (t1 << 14)) ^ (t1 >> 3));
 136
 137                                 t2 = buff[i - 2];
 138                                 t2 = (((t2 >> 17) | (t2 << 15)) ^ ((t2 >> 19) | (t2 << 13)) ^ (t2 >> 10));
 139                                 buff[i] = t2 + buff[i - 7] + t1 + buff[i - 16];
 140                         }
 141
 142                         a = _H[0];
 143                         b = _H[1];
 144                         c = _H[2];
 145                         d = _H[3];
 146                         e = _H[4];
 147                         f = _H[5];
 148                         g = _H[6];
 149                         h = _H[7];
 150
 151                         for (i=0; i<64; i++) {
 152                                 t1 = h + (((e >> 6) | (e << 26)) ^ ((e >> 11) | (e << 21)) ^ ((e >> 25) | (e << 7))) + ((e & f) ^ (~e & g)) + K1[i] + buff[i];
 153
 154                                 t2 = (((a >> 2) | (a << 30)) ^ ((a >> 13) | (a << 19)) ^ ((a >> 22) | (a << 10)));
 155                                 t2 = t2 + ((a & b) ^ (a & c) ^ (b & c));
 156                                 h = g;
 157                                 g = f;
 158                                 f = e;
 159                                 e = d + t1;
 160                                 d = c;
 161                                 c = b;
 162                                 b = a;
 163                                 a = t1 + t2;
 164                         }
 165
 166                         _H[0] += a;
 167                         _H[1] += b;
 168                         _H[2] += c;
 169                         _H[3] += d;
 170                         _H[4] += e;
 171                         _H[5] += f;
 172                         _H[6] += g;
 173                         _H[7] += h;
 174                 }
 175
 176                 private void ProcessFinalBlock (byte[] inputBuffer, int inputOffset, int inputCount)
 177                 {
 178                         ulong total = count + (ulong)inputCount;
 179                         int paddingSize = (56 - (int)(total % BLOCK_SIZE_BYTES));
 180
 181                         if (paddingSize < 1)
 182                                 paddingSize += BLOCK_SIZE_BYTES;
 183
 184                         byte[] fooBuffer = new byte[inputCount+paddingSize+8];
 185
 186                         for (int i=0; i<inputCount; i++) {
 187                                 fooBuffer[i] = inputBuffer[i+inputOffset];
 188                         }
 189
 190                         fooBuffer[inputCount] = 0x80;
 191                         for (int i=inputCount+1; i<inputCount+paddingSize; i++) {
 192                                 fooBuffer[i] = 0x00;
 193                         }
 194
 195                         // I deal in bytes. The algorithm deals in bits.
 196                         ulong size = total << 3;
 197                         AddLength (size, fooBuffer, inputCount+paddingSize);
 198                         ProcessBlock (fooBuffer, 0);
 199
 200                         if (inputCount+paddingSize+8 == 128) {
 201                                 ProcessBlock(fooBuffer, 64);
 202                         }
 203                 }
 204
 205                 internal void AddLength (ulong length, byte[] buffer, int position)
 206                 {
 207                         buffer [position++] = (byte)(length >> 56);
 208                         buffer [position++] = (byte)(length >> 48);
 209                         buffer [position++] = (byte)(length >> 40);
 210                         buffer [position++] = (byte)(length >> 32);
 211                         buffer [position++] = (byte)(length >> 24);
 212                         buffer [position++] = (byte)(length >> 16);
 213                         buffer [position++] = (byte)(length >>  8);
 214                         buffer [position]   = (byte)(length);
 215                 }
 216         }
 217 }
 218