1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
|
# Implementation of the Lilliput-AE tweakable block cipher.
#
# Authors, hereby denoted as "the implementer":
# Kévin Le Gouguec,
# Léo Reynaud
# 2019.
#
# For more information, feedback or questions, refer to our website:
# https://paclido.fr/lilliput-ae
#
# To the extent possible under law, the implementer has waived all copyright
# and related or neighboring rights to the source code in this file.
# http://creativecommons.org/publicdomain/zero/1.0/
"""Lilliput-TBC tweakable block cipher.
This module provides functions to encrypt and decrypt blocks of 128 bits.
"""
from .constants import BLOCK_BYTES, SBOX
from .helpers import xor
from .multiplications import ALPHAS
_PERMUTATION = [14, 11, 12, 10, 8, 9, 13, 15, 3, 1, 4, 5, 6, 0, 2, 7]
_PERMUTATION_INV = [13, 9, 14, 8, 10, 11, 12, 15, 4, 5, 3, 1, 2, 6 ,0 ,7]
_ROUNDS = {
128: 32,
192: 36,
256: 42
}
def _build_tweakey(tweak, key):
return tweak+key
def _lane(TK, j):
return TK[j*8:(j+1)*8]
def _round_tweakey_schedule(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 _subtweakey_extract(tweakey, Ci):
RTKi = [0]*8
for j, byte in enumerate(tweakey):
RTKi[j%8] ^= byte
RTKi[0] ^= Ci
return RTKi
def _tweakey_schedule_whole(tweakey, r):
TKs = [tweakey]
RTKs = [_subtweakey_extract(TKs[0], 0)]
for i in range(1, r):
TKs.append(_round_tweakey_schedule(TKs[i-1]))
RTKs.append(_subtweakey_extract(TKs[i], i))
return RTKs
def _non_linear_layer(state, subtweakey):
variables_xored = xor(state, subtweakey)
variables_sboxed = [
SBOX[variables_xored[i]] for i in range(8)
]
state_output = state
for i in range(8):
state_output[15-i] ^= variables_sboxed[i]
return state_output
def _linear_layer(state):
state_output = state
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 _permutation_layer(state, p):
return [
state[p[i]] for i in range(BLOCK_BYTES)
]
def _one_round_egfn_enc(state, subtweakey):
state_non_linear = _non_linear_layer(state, subtweakey)
state_linear = _linear_layer(state_non_linear)
state_permutation = _permutation_layer(state_linear, _PERMUTATION)
return state_permutation
def _last_round_egfn(state, subtweakey):
state_non_linear = _non_linear_layer(state, subtweakey)
state_linear = _linear_layer(state_non_linear)
return state_linear
def _one_round_egfn_dec(state, subtweakey):
state_non_linear = _non_linear_layer(state, subtweakey)
state_linear = _linear_layer(state_non_linear)
state_permutation = _permutation_layer(state_linear, _PERMUTATION_INV)
return state_permutation
def encrypt(tweak, key, message):
r = _ROUNDS[8*len(key)]
tweakey = _build_tweakey(tweak, key)
RTKs = _tweakey_schedule_whole(tweakey, r)
state = message
for i in range(r-1):
state = _one_round_egfn_enc(state, RTKs[i])
return _last_round_egfn(state, RTKs[r-1])
def decrypt(tweak, key, cipher):
r = _ROUNDS[8*len(key)]
tweakey = _build_tweakey(tweak, key)
RTKs = _tweakey_schedule_whole(tweakey, r)
state = cipher
for i in range(r-1):
state = _one_round_egfn_dec(state, RTKs[r-i-1])
return _last_round_egfn(state, RTKs[0])
|
