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#include "pch.h"
#include "gost.h"
#include "misc.h"
NAMESPACE_BEGIN(CryptoPP)
// these are the S-boxes given in Applied Cryptography 2nd Ed., p. 333
const byte GOST::Base::sBox[8][16]={
{4, 10, 9, 2, 13, 8, 0, 14, 6, 11, 1, 12, 7, 15, 5, 3},
{14, 11, 4, 12, 6, 13, 15, 10, 2, 3, 8, 1, 0, 7, 5, 9},
{5, 8, 1, 13, 10, 3, 4, 2, 14, 15, 12, 7, 6, 0, 9, 11},
{7, 13, 10, 1, 0, 8, 9, 15, 14, 4, 6, 12, 11, 2, 5, 3},
{6, 12, 7, 1, 5, 15, 13, 8, 4, 10, 9, 14, 0, 3, 11, 2},
{4, 11, 10, 0, 7, 2, 1, 13, 3, 6, 8, 5, 9, 12, 15, 14},
{13, 11, 4, 1, 3, 15, 5, 9, 0, 10, 14, 7, 6, 8, 2, 12},
{1, 15, 13, 0, 5, 7, 10, 4, 9, 2, 3, 14, 6, 11, 8, 12}};
/* // these are the S-boxes given in the GOST source code listing in Applied
// Cryptography 2nd Ed., p. 644. they appear to be from the DES S-boxes
{13, 2, 8, 4, 6, 15, 11, 1, 10, 9, 3, 14, 5, 0, 12, 7 },
{ 4, 11, 2, 14, 15, 0, 8, 13, 3, 12, 9, 7, 5, 10, 6, 1 },
{12, 1, 10, 15, 9, 2, 6, 8, 0, 13, 3, 4, 14, 7, 5, 11 },
{ 2, 12, 4, 1, 7, 10, 11, 6, 8, 5, 3, 15, 13, 0, 14, 9 },
{ 7, 13, 14, 3, 0, 6, 9, 10, 1, 2, 8, 5, 11, 12, 4, 15 },
{10, 0, 9, 14, 6, 3, 15, 5, 1, 13, 12, 7, 11, 4, 2, 8 },
{15, 1, 8, 14, 6, 11, 3, 4, 9, 7, 2, 13, 12, 0, 5, 10 },
{14, 4, 13, 1, 2, 15, 11, 8, 3, 10, 6, 12, 5, 9, 0, 7 }};
*/
volatile bool GOST::Base::sTableCalculated = false;
word32 GOST::Base::sTable[4][256];
void GOST::Base::UncheckedSetKey(const byte *userKey, unsigned int length, const NameValuePairs &)
{
AssertValidKeyLength(length);
PrecalculateSTable();
GetUserKey(LITTLE_ENDIAN_ORDER, m_key.begin(), 8, userKey, KEYLENGTH);
}
void GOST::Base::PrecalculateSTable()
{
if (!sTableCalculated)
{
for (unsigned i = 0; i < 4; i++)
for (unsigned j = 0; j < 256; j++)
{
word32 temp = sBox[2*i][j%16] | (sBox[2*i+1][j/16] << 4);
sTable[i][j] = rotlMod(temp, 11+8*i);
}
sTableCalculated=true;
}
}
#define f(x) ( t=x, \
sTable[3][GETBYTE(t, 3)] ^ sTable[2][GETBYTE(t, 2)] \
^ sTable[1][GETBYTE(t, 1)] ^ sTable[0][GETBYTE(t, 0)] )
typedef BlockGetAndPut<word32, LittleEndian> Block;
void GOST::Enc::ProcessAndXorBlock(const byte *inBlock, const byte *xorBlock, byte *outBlock) const
{
word32 n1, n2, t;
Block::Get(inBlock)(n1)(n2);
for (unsigned int i=0; i<3; i++)
{
n2 ^= f(n1+m_key[0]);
n1 ^= f(n2+m_key[1]);
n2 ^= f(n1+m_key[2]);
n1 ^= f(n2+m_key[3]);
n2 ^= f(n1+m_key[4]);
n1 ^= f(n2+m_key[5]);
n2 ^= f(n1+m_key[6]);
n1 ^= f(n2+m_key[7]);
}
n2 ^= f(n1+m_key[7]);
n1 ^= f(n2+m_key[6]);
n2 ^= f(n1+m_key[5]);
n1 ^= f(n2+m_key[4]);
n2 ^= f(n1+m_key[3]);
n1 ^= f(n2+m_key[2]);
n2 ^= f(n1+m_key[1]);
n1 ^= f(n2+m_key[0]);
Block::Put(xorBlock, outBlock)(n2)(n1);
}
void GOST::Dec::ProcessAndXorBlock(const byte *inBlock, const byte *xorBlock, byte *outBlock) const
{
word32 n1, n2, t;
Block::Get(inBlock)(n1)(n2);
n2 ^= f(n1+m_key[0]);
n1 ^= f(n2+m_key[1]);
n2 ^= f(n1+m_key[2]);
n1 ^= f(n2+m_key[3]);
n2 ^= f(n1+m_key[4]);
n1 ^= f(n2+m_key[5]);
n2 ^= f(n1+m_key[6]);
n1 ^= f(n2+m_key[7]);
for (unsigned int i=0; i<3; i++)
{
n2 ^= f(n1+m_key[7]);
n1 ^= f(n2+m_key[6]);
n2 ^= f(n1+m_key[5]);
n1 ^= f(n2+m_key[4]);
n2 ^= f(n1+m_key[3]);
n1 ^= f(n2+m_key[2]);
n2 ^= f(n1+m_key[1]);
n1 ^= f(n2+m_key[0]);
}
Block::Put(xorBlock, outBlock)(n2)(n1);
}
NAMESPACE_END
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