public void ShiftLeftWrapped(BLOCK8BYTE S, int iBitShift)
{
// this shift is only applied to the first 32 bits, and parity bit is ignored
// Declaration of local variables
int iByteOffset = 0;
bool bBit = false;
// Copy byte and shift regardless
for (iByteOffset = 0; iByteOffset < 4; iByteOffset++)
{
m_data[iByteOffset] = Convert.ToByte((S.m_data[iByteOffset] << iBitShift) & 0xFF);
}
// if shifting by 1...
if (iBitShift == 1)
{
// repair bits on right of BYTE
for (iByteOffset = 0; iByteOffset < 3; iByteOffset++)
{
// get repairing bit offsets
bBit = S.GetBit(iByteOffset + 1, 7);
this.SetBit(iByteOffset, 1, bBit);
}
// wrap around the final bit
this.SetBit(3, 1, S.GetBit(0, 7));
}
else if (iBitShift == 2)
{
// repair bits on right of BYTE
for (iByteOffset = 0; iByteOffset < 3; iByteOffset++)
{
// get repairing bit offsets
bBit = S.GetBit(iByteOffset + 1, 7);
this.SetBit(iByteOffset, 2, bBit);
bBit = S.GetBit(iByteOffset + 1, 6);
this.SetBit(iByteOffset, 1, bBit);
}
// wrap around the final bit
this.SetBit(3, 2, S.GetBit(0, 7));
this.SetBit(3, 1, S.GetBit(0, 6));
}
#if DEBUG
else
{
Debug.Assert(false);
}
#endif // #if DEBUG
}
public void ShiftLeftWrapped(BLOCK8BYTE S, int iBitShift)
{
// this shift is only applied to the first 32 bits, and parity bit is ignored
// Declaration of local variables
int iByteOffset = 0;
bool bBit = false;
// Copy byte and shift regardless
for (iByteOffset = 0; iByteOffset < 4; iByteOffset++)
m_data[iByteOffset] = Convert.ToByte((S.m_data[iByteOffset] << iBitShift) & 0xFF);
// if shifting by 1...
if (iBitShift == 1)
{
// repair bits on right of BYTE
for (iByteOffset = 0; iByteOffset < 3; iByteOffset++)
{
// get repairing bit offsets
bBit = S.GetBit(iByteOffset + 1, 7);
this.SetBit(iByteOffset, 1, bBit);
}
// wrap around the final bit
this.SetBit(3, 1, S.GetBit(0, 7));
}
else if (iBitShift == 2)
{
// repair bits on right of BYTE
for (iByteOffset = 0; iByteOffset < 3; iByteOffset++)
{
// get repairing bit offsets
bBit = S.GetBit(iByteOffset + 1, 7);
this.SetBit(iByteOffset, 2, bBit);
bBit = S.GetBit(iByteOffset + 1, 6);
this.SetBit(iByteOffset, 1, bBit);
}
// wrap around the final bit
this.SetBit(3, 2, S.GetBit(0, 7));
this.SetBit(3, 1, S.GetBit(0, 6));
}
#if DEBUG
else
Debug.Assert(false);
#endif // #if DEBUG
}
private static KEY_SET _expandKey(byte[] Key, int iOffset)
{
//
// Expand an 8 byte DES key into a set of permuted keys
//
// Declare return variable
KEY_SET Ftmp = new KEY_SET();
// Declaration of local variables
int iTableOffset, iArrayOffset, iPermOffset, iByteOffset, iBitOffset;
bool bBit;
// Put key into an 8-bit block
BLOCK8BYTE K = new BLOCK8BYTE();
K.Set(Key, iOffset);
// Permutate Kp with PC1
BLOCK8BYTE Kp = new BLOCK8BYTE();
for (iArrayOffset = 0; iArrayOffset < bytePC1.Length; iArrayOffset++)
{
// Get permute offset
iPermOffset = bytePC1[iArrayOffset];
iPermOffset--;
// Get and set bit
Kp.SetBit(
_bitAddressToByteOffset(iArrayOffset, 7),
_bitAddressToBitOffset(iArrayOffset, 7),
K.GetBit(
_bitAddressToByteOffset(iPermOffset, 8),
_bitAddressToBitOffset(iPermOffset, 8)
)
);
}
// Create 17 blocks of C and D from Kp
BLOCK8BYTE[] KpCn = new BLOCK8BYTE[17];
BLOCK8BYTE[] KpDn = new BLOCK8BYTE[17];
for (iArrayOffset = 0; iArrayOffset < 17; iArrayOffset++)
{
KpCn[iArrayOffset] = new BLOCK8BYTE();
KpDn[iArrayOffset] = new BLOCK8BYTE();
}
for (iArrayOffset = 0; iArrayOffset < 32; iArrayOffset++)
{
// Set bit in KpCn
iByteOffset = _bitAddressToByteOffset(iArrayOffset, 8);
iBitOffset = _bitAddressToBitOffset(iArrayOffset, 8);
bBit = Kp.GetBit(iByteOffset, iBitOffset);
KpCn[0].SetBit(iByteOffset, iBitOffset, bBit);
// Set bit in KpDn
bBit = Kp.GetBit(iByteOffset + 4, iBitOffset);
KpDn[0].SetBit(iByteOffset, iBitOffset, bBit);
}
for (iArrayOffset = 1; iArrayOffset < 17; iArrayOffset++)
{
// Shift left wrapped
KpCn[iArrayOffset].ShiftLeftWrapped(KpCn[iArrayOffset - 1], byteShifts[iArrayOffset - 1]);
KpDn[iArrayOffset].ShiftLeftWrapped(KpDn[iArrayOffset - 1], byteShifts[iArrayOffset - 1]);
}
// Create 17 keys Kn
for (iArrayOffset = 0; iArrayOffset < 17; iArrayOffset++)
{
// Loop through the bits
for (iTableOffset = 0; iTableOffset < 48; iTableOffset++)
{
// Get address if bit
iPermOffset = bytePC2[iTableOffset];
iPermOffset--;
// Convert to byte and bit offsets
iByteOffset = _bitAddressToByteOffset(iPermOffset, 7);
iBitOffset = _bitAddressToBitOffset(iPermOffset, 7);
// Get bit
if (iByteOffset < 4)
bBit = KpCn[iArrayOffset].GetBit(iByteOffset, iBitOffset);
else
bBit = KpDn[iArrayOffset].GetBit(iByteOffset - 4, iBitOffset);
// Set bit
iByteOffset = _bitAddressToByteOffset(iTableOffset, 6);
iBitOffset = _bitAddressToBitOffset(iTableOffset, 6);
Ftmp.GetAt(iArrayOffset).SetBit(iByteOffset, iBitOffset, bBit);
}
}
// Return variable
return Ftmp;
}
private static KEY_SET _expandKey(byte[] Key, int iOffset)
{
//
// Expand an 8 byte DES key into a set of permuted keys
//
// Declare return variable
KEY_SET Ftmp = new KEY_SET();
// Declaration of local variables
int iTableOffset, iArrayOffset, iPermOffset, iByteOffset, iBitOffset;
bool bBit;
// Put key into an 8-bit block
BLOCK8BYTE K = new BLOCK8BYTE();
K.Set(Key, iOffset);
// Permutate Kp with PC1
BLOCK8BYTE Kp = new BLOCK8BYTE();
for (iArrayOffset = 0; iArrayOffset < bytePC1.Length; iArrayOffset++)
{
// Get permute offset
iPermOffset = bytePC1[iArrayOffset];
iPermOffset--;
// Get and set bit
Kp.SetBit(
_bitAddressToByteOffset(iArrayOffset, 7),
_bitAddressToBitOffset(iArrayOffset, 7),
K.GetBit(
_bitAddressToByteOffset(iPermOffset, 8),
_bitAddressToBitOffset(iPermOffset, 8)
)
);
}
// Create 17 blocks of C and D from Kp
BLOCK8BYTE[] KpCn = new BLOCK8BYTE[17];
BLOCK8BYTE[] KpDn = new BLOCK8BYTE[17];
for (iArrayOffset = 0; iArrayOffset < 17; iArrayOffset++)
{
KpCn[iArrayOffset] = new BLOCK8BYTE();
KpDn[iArrayOffset] = new BLOCK8BYTE();
}
for (iArrayOffset = 0; iArrayOffset < 32; iArrayOffset++)
{
// Set bit in KpCn
iByteOffset = _bitAddressToByteOffset(iArrayOffset, 8);
iBitOffset = _bitAddressToBitOffset(iArrayOffset, 8);
bBit = Kp.GetBit(iByteOffset, iBitOffset);
KpCn[0].SetBit(iByteOffset, iBitOffset, bBit);
// Set bit in KpDn
bBit = Kp.GetBit(iByteOffset + 4, iBitOffset);
KpDn[0].SetBit(iByteOffset, iBitOffset, bBit);
}
for (iArrayOffset = 1; iArrayOffset < 17; iArrayOffset++)
{
// Shift left wrapped
KpCn[iArrayOffset].ShiftLeftWrapped(KpCn[iArrayOffset - 1], byteShifts[iArrayOffset - 1]);
KpDn[iArrayOffset].ShiftLeftWrapped(KpDn[iArrayOffset - 1], byteShifts[iArrayOffset - 1]);
}
// Create 17 keys Kn
for (iArrayOffset = 0; iArrayOffset < 17; iArrayOffset++)
{
// Loop through the bits
for (iTableOffset = 0; iTableOffset < 48; iTableOffset++)
{
// Get address if bit
iPermOffset = bytePC2[iTableOffset];
iPermOffset--;
// Convert to byte and bit offsets
iByteOffset = _bitAddressToByteOffset(iPermOffset, 7);
iBitOffset = _bitAddressToBitOffset(iPermOffset, 7);
// Get bit
if (iByteOffset < 4)
{
bBit = KpCn[iArrayOffset].GetBit(iByteOffset, iBitOffset);
}
else
{
bBit = KpDn[iArrayOffset].GetBit(iByteOffset - 4, iBitOffset);
}
// Set bit
iByteOffset = _bitAddressToByteOffset(iTableOffset, 6);
iBitOffset = _bitAddressToBitOffset(iTableOffset, 6);
Ftmp.GetAt(iArrayOffset).SetBit(iByteOffset, iBitOffset, bBit);
}
}
// Return variable
return(Ftmp);
}