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"""
Lilliput TBC
"""
from .constants import BLOCK_BYTES, Sbox
from .multiplications import ALPHAS
permutation = [14, 11, 12, 10, 8, 9, 13, 15, 3, 1, 4, 5, 6, 0, 2, 7]
permutationInv = [13, 9, 14, 8, 10, 11, 12, 15, 4, 5, 3, 1, 2, 6 ,0 ,7]
################################################################################
def BuildTweakey(tweak, key):
return tweak+key
#############################
def _lane(TK, j):
return TK[j*8:(j+1)*8]
def RoundTweakeySchedule(tweakey):
p = len(tweakey)//8
multiplied_lanes = (
ALPHAS[j](_lane(tweakey, j)) for j in range(p)
)
return [byte for lane in multiplied_lanes for byte in lane]
def SubTweakeyExtract(tweakey, Ci):
RTKi = [0]*8
for j, byte in enumerate(tweakey):
RTKi[j%8] ^= byte
RTKi[0] ^= Ci
return RTKi
def TweakeyScheduleWhole(tweakey, r):
# store main tweakey in TKs[0]
# and corresponding round tweakey in RTKs[0]
TKs = [tweakey]
RTKs = [SubTweakeyExtract(TKs[0], 0)]
for i in range(1, r):
TKs.append(RoundTweakeySchedule(TKs[i-1]))
RTKs.append(SubTweakeyExtract(TKs[i], i))
return RTKs
################################################################################
def NonLinearLayer(state, subtweakey):
variables_xored = [0 for byte in range(0, 8)]
for byte in range(0,8):
variables_xored[byte] = state[byte] ^ subtweakey[byte]
variables_sboxed = [0 for byte in range(0, 8)]
for byte in range(0, 8):
variables_sboxed[byte] = Sbox[variables_xored[byte]]
state_output = [0 for byte in range(0, BLOCK_BYTES)]
for byte in range(0,BLOCK_BYTES):
state_output[byte] = state[byte]
for byte in range(0, 8):
state_output[15 - byte] ^= variables_sboxed[byte]
return state_output
def LinearLayer(state):
state_output = [0 for byte in range(0, BLOCK_BYTES)]
for byte in range(0, BLOCK_BYTES):
state_output[byte] = state[byte]
for byte in range(1, 8):
state_output[15] ^= state[byte]
for byte in range(9, 15):
state_output[byte] ^= state[7]
return state_output
def PermutationLayerEnc(state):
state_output = [0 for byte in range(0, BLOCK_BYTES)]
for byte in range(0, BLOCK_BYTES):
state_output[byte] = state[permutation[byte]]
return state_output
def PermutationLayerDec(state):
state_output = [0 for byte in range(0, BLOCK_BYTES)]
for byte in range(0, BLOCK_BYTES):
state_output[byte] = state[permutationInv[byte]]
return state_output
def OneRoundEGFNEnc(state, subtweakey):
state_non_linear = NonLinearLayer(state, subtweakey)
state_linear = LinearLayer(state_non_linear)
state_permutation = PermutationLayerEnc(state_linear)
return state_permutation
def LastRoundEGFN(state, subtweakey):
state_non_linear = NonLinearLayer(state, subtweakey)
state_linear = LinearLayer(state_non_linear)
return state_linear
def OneRoundEGFNDec(state, subtweakey):
state_non_linear = NonLinearLayer(state, subtweakey)
state_linear = LinearLayer(state_non_linear)
state_permutation = PermutationLayerDec(state_linear)
return state_permutation
def _rounds(key_bytes):
rounds = {
128: 32,
192: 36,
256: 42
}
return rounds[key_bytes*8]
################################################################################
# Lilliput TBC
def encrypt(tweak, key, message):
r = _rounds(len(key))
tweakey = BuildTweakey(tweak, key)
RTKs = TweakeyScheduleWhole(tweakey, r)
state = [0 for byte in range(0, BLOCK_BYTES)]
for byte in range(0, BLOCK_BYTES):
state[byte] = message[byte]
for i in range(0, r-1):
state_output = OneRoundEGFNEnc(state, RTKs[i])
for byte in range(0, BLOCK_BYTES):
state[byte] = state_output[byte]
state_output = LastRoundEGFN(state, RTKs[r-1])
return state_output
def decrypt(tweak, key, cipher):
r = _rounds(len(key))
tweakey = BuildTweakey(tweak, key)
RTKs = TweakeyScheduleWhole(tweakey, r)
state = [0 for byte in range(0, BLOCK_BYTES)]
for byte in range(0, BLOCK_BYTES):
state[byte] = cipher[byte]
for i in range(0, r-1):
state_output = OneRoundEGFNDec(state, RTKs[r-i-1])
for byte in range(0, BLOCK_BYTES):
state[byte] = state_output[byte]
state_output = LastRoundEGFN(state, RTKs[0])
return state_output
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