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/*************************************************
* GOST Source File *
* (C) 1999-2007 The Botan Project *
*************************************************/
#include <botan/gost.h>
#include <botan/bit_ops.h>
namespace Botan {
/*************************************************
* GOST Encryption *
*************************************************/
void GOST::enc(const byte in[], byte out[]) const
{
u32bit N1 = make_u32bit(in[3], in[2], in[1], in[0]),
N2 = make_u32bit(in[7], in[6], in[5], in[4]);
for(u32bit j = 0; j != 32; j += 2)
{
u32bit T0;
T0 = N1 + EK[j];
N2 ^= SBOX1[get_byte(0, T0)] | SBOX2[get_byte(1, T0)] |
SBOX3[get_byte(2, T0)] | SBOX4[get_byte(3, T0)];
T0 = N2 + EK[j+1];
N1 ^= SBOX1[get_byte(0, T0)] | SBOX2[get_byte(1, T0)] |
SBOX3[get_byte(2, T0)] | SBOX4[get_byte(3, T0)];
}
out[0] = get_byte(3, N2); out[1] = get_byte(2, N2);
out[2] = get_byte(1, N2); out[3] = get_byte(0, N2);
out[4] = get_byte(3, N1); out[5] = get_byte(2, N1);
out[6] = get_byte(1, N1); out[7] = get_byte(0, N1);
}
/*************************************************
* GOST Decryption *
*************************************************/
void GOST::dec(const byte in[], byte out[]) const
{
u32bit N1 = make_u32bit(in[3], in[2], in[1], in[0]),
N2 = make_u32bit(in[7], in[6], in[5], in[4]);
for(u32bit j = 0; j != 32; j += 2)
{
u32bit T0;
T0 = N1 + EK[31-j];
N2 ^= SBOX1[get_byte(0, T0)] | SBOX2[get_byte(1, T0)] |
SBOX3[get_byte(2, T0)] | SBOX4[get_byte(3, T0)];
T0 = N2 + EK[30-j];
N1 ^= SBOX1[get_byte(0, T0)] | SBOX2[get_byte(1, T0)] |
SBOX3[get_byte(2, T0)] | SBOX4[get_byte(3, T0)];
}
out[0] = get_byte(3, N2); out[1] = get_byte(2, N2);
out[2] = get_byte(1, N2); out[3] = get_byte(0, N2);
out[4] = get_byte(3, N1); out[5] = get_byte(2, N1);
out[6] = get_byte(1, N1); out[7] = get_byte(0, N1);
}
/*************************************************
* GOST Key Schedule *
*************************************************/
void GOST::key(const byte key[], u32bit)
{
for(u32bit j = 0; j != 8; ++j)
{
u32bit K = make_u32bit(key[4*j+3], key[4*j+2], key[4*j+1], key[4*j]);
EK[j] = EK[j+8] = EK[j+16] = K;
}
for(u32bit j = 24; j != 32; ++j)
EK[j] = EK[7-(j-24)];
}
}
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