// Дешифрование одного блока
private ulong Decrypt(ulong textBit64, uint[] roundsKeys)
{
ulong[] L = new ulong[18];
ulong[] R = new ulong[18];
// тут наоборот в отличии от Encrypt
L[17] = (textBit64 >> 32);
R[17] = WorkWithBits.GetLowBits(textBit64, 32);
R[16] = R[17] ^ roundsKeys[16];
L[16] = L[17] ^ roundsKeys[17];
uint tmp = (uint)R[16];
R[16] = L[16];
L[16] = tmp;
// тут тоже наоборот
for (int i = 15; i >= 0; i--)
{
R[i] = L[i + 1] ^ F_Transformation((uint)(roundsKeys[i] ^ R[i + 1]));
L[i] = R[i + 1];
}
ulong answer = (L[0] << 32) | R[0];
return(answer);
}
// Шифрование одного блока
private ulong Encrypt(ulong textBit64, uint[] roundsKeys)
{
// правая-левая части
ulong[] L = new ulong[18];
ulong[] R = new ulong[18];
L[0] = (textBit64 >> 32);
R[0] = WorkWithBits.GetLowBits(textBit64, 32);
// цикл раундов
for (int i = 0; i < 16; i++)
{
L[i + 1] = R[i] ^ F_Transformation((uint)(roundsKeys[i] ^ L[i]));
R[i + 1] = L[i];
}
uint tmp = (uint)R[16];
R[16] = L[16];
L[16] = tmp;
R[17] = R[16] ^ roundsKeys[16];
L[17] = L[16] ^ roundsKeys[17];
// склеиваем половинки
ulong answer = (L[17] << 32) | R[17];
return(answer);
}
// F преобразование
private uint F_Transformation(uint block)
{
uint answer = BlowfishSumWithMod(_Sblocks[0][WorkWithBits.CutBitsWithBeginningAndEndingPlaces(block, 0, 7)],
_Sblocks[1][WorkWithBits.CutBitsWithBeginningAndEndingPlaces(block, 8, 15)]);
answer = answer ^ (uint)_Sblocks[2][WorkWithBits.CutBitsWithBeginningAndEndingPlaces(block, 16, 23)];
answer = BlowfishSumWithMod(answer, _Sblocks[3][WorkWithBits.CutBitsWithBeginningAndEndingPlaces(block, 24, 31)]);
return(answer);
}
