def PC_2(CiDi):
'''
Permutation Choice 2.
Drop 8 bits and permute the remaining 48 input bits.
56-bit -> 48-bit
'''
return (Permute(CiDi, PC_2_table)) # ok
def PC_1(key):
'''
Permutation Choice 1
Discard the parity check bits, which cuts the 64-bit key into 56-bit key and then permute.
64-bit -> 56-bit
'''
return (Permute(key, PC_1_table)) # ok
def IP(block):
'''
Initial permutation
'''
return Permute(block, IP_table) # ok
def Permutation(HalfBlock):
'''
Rearrange the 32 outputs from the S-boxes according to a fixed permutation
'''
return Permute(HalfBlock, Permutation_table) # ok
def Expansion(HalfBlock):
'''
Expand 32-bit half-block to 48 bits using the expansion permutation.
32-bit -> 48-bit
'''
return Permute(HalfBlock, Expansion_table) # ok
def FP(block):
'''
Final permutation
'''
return Permute(block, FP_table) # ok