In DES the least significant bit of each key byte is used as parity bit and does not affect the en-/decryption process.
0xcc in binary is 11001100 while 0xcd is 11001101. Only the last bit (least significant bit) is different and therefore both produce the same result.
Edit: DES keys are still being provided with 64 bits but 8 of them are ignored making the effective key size 56 bits.
0xcc in binary is 11001100 while 0xcd is 11001101. Only the last bit (least significant bit) is different and therefore both produce the same result.
Edit: DES keys are still being provided with 64 bits but 8 of them are ignored making the effective key size 56 bits.