void BlowFish::InitTables()
{
for ( int tempKey = 0; tempKey < CRYPT_GAMEKEY_COUNT; tempKey++ )
{
memcpy( p_table[tempKey], p_box, sizeof( p_box ) );
memcpy( s_table[tempKey], s_box, sizeof( s_box ) );
unsigned char *pAct = key_table[tempKey];
int j = 0;
for ( int i = 0; i < 18; i++ )
{
unsigned int mask = 0x00000000;
for ( int k = 0; k < 4; ++k )
{
mask = ( mask << 8 ) | *pAct++;
if ( ++j >= CRYPT_GAMEKEY_LENGTH )
{
j = 0;
pAct = key_table[tempKey];
}
}
p_table[tempKey][i] ^= mask;
}
unsigned int value[2];
value[0] = value[1] = 0;
for ( int i = 0; i < 18; i += 2 )
{
RawDecrypt( value, tempKey );
p_table[tempKey][i] = value[0];
p_table[tempKey][i + 1] = value[1];
}
for ( int i = 0; i < 1024; i += 2 )
{
RawDecrypt( value, tempKey );
s_table[tempKey][i] = value[0];
s_table[tempKey][i + 1] = value[1];
}
}
tables_ready = true;
}
unsigned int ElGamalDecryptor::Decrypt(const byte *cipherText, byte *plainText)
{
Integer a(cipherText, modulusLen);
Integer b(cipherText+modulusLen, modulusLen);
Integer m;
RawDecrypt(a, b, m);
m.Encode(plainText, 1);
unsigned int plainTextLength = plainText[0];
if (plainTextLength > MaxPlainTextLength())
return 0;
m >>= 8;
m.Encode(plainText, plainTextLength);
return plainTextLength;
}
void BlowFish::Decrypt( unsigned char * in, unsigned char * out, int len )
{
if ( stream_pos + len > CRYPT_GAMETABLE_TRIGGER )
{
int len_rem = CRYPT_GAMETABLE_TRIGGER - stream_pos;
Decrypt( in, out, len_rem );
table_index = ( table_index + CRYPT_GAMETABLE_STEP ) % CRYPT_GAMETABLE_MODULO;
memcpy( game_seed, seed_table[1][table_index][0], CRYPT_GAMESEED_LENGTH );
stream_pos = 0;
block_pos = 0;
in += len_rem;
out += len_rem;
len -= len_rem;
}
for ( int tempPos = 0; tempPos < len; tempPos++ )
{
if ( !block_pos )
{
unsigned int values[2];
unsigned char *pKey = game_seed;
N2L( pKey, values[0] );
N2L( pKey, values[1] );
RawDecrypt( (unsigned int *)values, table_index );
pKey = game_seed;
L2N( values[0], pKey );
L2N( values[1], pKey );
}
block_pos &= 0x07;
unsigned char c = *in++;
*out++ = game_seed[block_pos] ^ c;
game_seed[block_pos] = c;
block_pos = ( block_pos + 1 ) & 0x07;
}
stream_pos += len;
}
