gost.cpp Source File

00001 #include "pch.h"
00002 #include "gost.h"
00003 
00004 NAMESPACE_BEGIN(CryptoPP)
00005 
00006 // these are the S-boxes given in Applied Cryptography 2nd Ed., p. 333
00007 const byte GOST::sBox[8][16]={
00008         {4, 10, 9, 2, 13, 8, 0, 14, 6, 11, 1, 12, 7, 15, 5, 3},
00009         {14, 11, 4, 12, 6, 13, 15, 10, 2, 3, 8, 1, 0, 7, 5, 9},
00010         {5, 8, 1, 13, 10, 3, 4, 2, 14, 15, 12, 7, 6, 0, 9, 11},
00011         {7, 13, 10, 1, 0, 8, 9, 15, 14, 4, 6, 12, 11, 2, 5, 3},
00012         {6, 12, 7, 1, 5, 15, 13, 8, 4, 10, 9, 14, 0, 3, 11, 2},
00013         {4, 11, 10, 0, 7, 2, 1, 13, 3, 6, 8, 5, 9, 12, 15, 14},
00014         {13, 11, 4, 1, 3, 15, 5, 9, 0, 10, 14, 7, 6, 8, 2, 12},
00015         {1, 15, 13, 0, 5, 7, 10, 4, 9, 2, 3, 14, 6, 11, 8, 12}};
00016 
00017 /*      // these are the S-boxes given in the GOST source code listing in Applied
00018         // Cryptography 2nd Ed., p. 644.  they appear to be from the DES S-boxes
00019         {13,  2,  8,  4,  6, 15, 11,  1, 10,  9,  3, 14,  5,  0, 12,  7 },
00020         { 4, 11,  2, 14, 15,  0,  8, 13,  3, 12,  9,  7,  5, 10,  6,  1 },
00021         {12,  1, 10, 15,  9,  2,  6,  8,  0, 13,  3,  4, 14,  7,  5, 11 },
00022         { 2, 12,  4,  1,  7, 10, 11,  6,  8,  5,  3, 15, 13,  0, 14,  9 },
00023         { 7, 13, 14,  3,  0,  6,  9, 10,  1,  2,  8,  5, 11, 12,  4, 15 },
00024         {10,  0,  9, 14,  6,  3, 15,  5,  1, 13, 12,  7, 11,  4,  2,  8 },
00025         {15,  1,  8, 14,  6, 11,  3,  4,  9,  7,  2, 13, 12,  0,  5, 10 },
00026         {14,  4, 13,  1,  2, 15, 11,  8,  3, 10,  6, 12,  5,  9,  0,  7 }}; 
00027 */
00028 
00029 bool GOST::sTableCalculated = false;
00030 word32 GOST::sTable[4][256];
00031 
00032 GOST::GOST(const byte *userKey, CipherDir)
00033         : key(8)
00034 {
00035         PrecalculateSTable();
00036 
00037         GetUserKeyLittleEndian(key.ptr, 8, userKey, KEYLENGTH);
00038 }
00039 
00040 void GOST::PrecalculateSTable()
00041 {
00042         if (!sTableCalculated)
00043         {
00044                 for (unsigned i = 0; i < 4; i++)
00045                         for (unsigned j = 0; j < 256; j++) 
00046                         {
00047                                 word32 temp = sBox[2*i][j%16] | (sBox[2*i+1][j/16] << 4);
00048                                 sTable[i][j] = rotlMod(temp, 11+8*i);
00049                         }
00050 
00051                 sTableCalculated=true;
00052         }
00053 }
00054 
00055 #define f(x)  ( t=x,                                                                                            \
00056                                 sTable[3][GETBYTE(t, 3)] ^ sTable[2][GETBYTE(t, 2)]     \
00057                           ^ sTable[1][GETBYTE(t, 1)] ^ sTable[0][GETBYTE(t, 0)] )
00058 
00059 void GOSTEncryption::ProcessBlock(const byte *inBlock, byte * outBlock) const
00060 {
00061         word32 n1, n2, t;
00062 
00063         GetBlockLittleEndian(inBlock, n1, n2);
00064 
00065         for (unsigned int i=0; i<3; i++)
00066         {
00067                 n2 ^= f(n1+key[0]);
00068                 n1 ^= f(n2+key[1]);
00069                 n2 ^= f(n1+key[2]);
00070                 n1 ^= f(n2+key[3]);
00071                 n2 ^= f(n1+key[4]);
00072                 n1 ^= f(n2+key[5]);
00073                 n2 ^= f(n1+key[6]);
00074                 n1 ^= f(n2+key[7]);
00075         }
00076 
00077         n2 ^= f(n1+key[7]);
00078         n1 ^= f(n2+key[6]);
00079         n2 ^= f(n1+key[5]);
00080         n1 ^= f(n2+key[4]);
00081         n2 ^= f(n1+key[3]);
00082         n1 ^= f(n2+key[2]);
00083         n2 ^= f(n1+key[1]);
00084         n1 ^= f(n2+key[0]);
00085 
00086         PutBlockLittleEndian(outBlock, n2, n1);
00087 }
00088 
00089 void GOSTDecryption::ProcessBlock(const byte *inBlock, byte * outBlock) const
00090 {
00091         word32 n1, n2, t;
00092 
00093         GetBlockLittleEndian(inBlock, n1, n2);
00094 
00095         n2 ^= f(n1+key[0]);
00096         n1 ^= f(n2+key[1]);
00097         n2 ^= f(n1+key[2]);
00098         n1 ^= f(n2+key[3]);
00099         n2 ^= f(n1+key[4]);
00100         n1 ^= f(n2+key[5]);
00101         n2 ^= f(n1+key[6]);
00102         n1 ^= f(n2+key[7]);
00103 
00104         for (unsigned int i=0; i<3; i++)
00105         {
00106                 n2 ^= f(n1+key[7]);
00107                 n1 ^= f(n2+key[6]);
00108                 n2 ^= f(n1+key[5]);
00109                 n1 ^= f(n2+key[4]);
00110                 n2 ^= f(n1+key[3]);
00111                 n1 ^= f(n2+key[2]);
00112                 n2 ^= f(n1+key[1]);
00113                 n1 ^= f(n2+key[0]);
00114         }
00115 
00116         PutBlockLittleEndian(outBlock, n2, n1);
00117 }
00118 
00119 NAMESPACE_END