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
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
|
"""
OCB 3 for lilliput ae i
"""
import lilliput_tbc as ltbc
from helpers import ArrayToBlockbytesMatrix, BlockbytesMatrixToBytes
BLOCK_BITS = 128
KEY_BITS = 128
TWEAK_BITS = 192
TWEAKEY_BITS = KEY_BITS + TWEAK_BITS
LANE_BITS = 64
LANES = int((TWEAKEY_BITS) / LANE_BITS)
ROUNDS = 32
BLOCK_BYTES = int(BLOCK_BITS / 8)
KEY_BYTES = int(KEY_BITS / 8)
TWEAK_BYTES = int(TWEAK_BITS / 8)
TWEAKEY_BYTES = int(TWEAKEY_BITS / 8)
A_BITS = BLOCK_BITS
M_BITS = BLOCK_BITS
N_BITS = 120
N_BYTES = int(N_BITS / 8)
def InitParameters(key_bits = 128, tweak_bits = 192, rounds = 32) :
global KEY_BITS
global KEY_BYTES
global TWEAK_BITS
global TWEAK_BYTES
global TWEAKEY_BITS
global TWEAKEY_BYTES
global LANES
global ROUNDS
KEY_BITS = key_bits
TWEAK_BITS = tweak_bits
TWEAKEY_BITS = KEY_BITS + TWEAK_BITS
LANES = int((TWEAKEY_BITS) / LANE_BITS)
ROUNDS = rounds
KEY_BYTES = int(KEY_BITS / 8)
TWEAK_BYTES = int(TWEAK_BITS / 8)
TWEAKEY_BYTES = int(TWEAKEY_BITS / 8)
###############################################################################
def XorState(state1, state2) :
state_output = [state1[byte] ^ state2[byte] for byte in range(0, len(state1))]
return state_output
def Padding10LSB(array, number_bits) :
shifted = 0
for byte in range(0, len(array)) :
shifted |= (array[byte] << (8 * byte))
shifted = (shifted << (BLOCK_BITS - number_bits)) & 0xffffffffffffffffffffffffffffffff
padded = shifted | (0x1 << (BLOCK_BITS - number_bits - 1))
array_padded = [0 for byte in range(0, BLOCK_BYTES)]
for byte in range(0, BLOCK_BYTES) :
array_padded[byte] = (padded & (0xff << (8 * byte))) >> (8 * byte)
return array_padded
def LowPart(array, number_bits) :
shifted = 0
for byte in range(0, len(array)) :
shifted |= (array[byte] << (8 * byte))
mask = 0
for bit in range(0, number_bits) :
mask |= (0x1 << bit)
lower_part = shifted & mask
will_padd = 0
if (number_bits % 8) != 0 :
will_padd = 1
lower_part_byte = [0 for byte in range(0, int(number_bits / 8) + will_padd)]
for byte in range(0, int(number_bits / 8) + will_padd) :
lower_part_byte[byte] = lower_part & 0xff
lower_part = lower_part >> 8
return lower_part_byte
###############################################################################
def TweakAssociatedData(i, padded = 0) :
tweak = [0 for byte in range(0, TWEAK_BYTES)]
mask = 0xff
for byte in range(0, TWEAK_BYTES - 1) :
tweak[byte] = (i & mask) >> (byte * 8)
mask = mask << 8
mask = (0xf << (8 * (TWEAK_BYTES - 1)))
tweak[TWEAK_BYTES - 1] = (i & mask) >> ((TWEAK_BYTES - 1) * 8)
if padded == 0 :
tweak[TWEAK_BYTES - 1] |= 0x20
else :
tweak[TWEAK_BYTES - 1] |= 0x60
return tweak
def BuildAuth(A, key) :
Auth = [0 for byte in range(0, BLOCK_BYTES)]
l_a = int(A_BITS / BLOCK_BITS)
if int(A_BITS % BLOCK_BITS) > 0 :
will_padd = 1
else :
will_padd = 0
for i in range(0, l_a) :
tweak = TweakAssociatedData(i, padded = 0)
enc = ltbc.LilliputTBCEnc(tweak, key, A[i])
Auth = XorState(Auth, enc)
if (A_BITS % BLOCK_BITS) == 0 :
return Auth
tweak = TweakAssociatedData(l_a, padded = 1)
ad_padded = Padding10LSB(A[l_a], (A_BITS % BLOCK_BITS))
enc = ltbc.LilliputTBCEnc(tweak, key, ad_padded)
Auth = XorState(Auth, enc)
return Auth
################################################################################
def TweakMessage(N, j, null = 0, padded = 0, final_padded = 0) :
tweak = [0 for byte in range(0, TWEAK_BYTES)]
for byte in range(N_BYTES - 1, -1, -1) :
tweak[byte + (TWEAK_BYTES - N_BYTES)] |= (N[byte] & 0xf0) >> 4
tweak[byte + (TWEAK_BYTES - N_BYTES - 1)] |= (N[byte] & 0x0f) << 4
tweak[TWEAK_BYTES - N_BYTES - 1] |= ((j >> 64) & 0xf)
for byte in range(TWEAK_BYTES - N_BYTES - 2, -1, -1) :
tweak[byte] = (j >> (8 * byte)) & 0xff
if null == 1 :
tweak[TWEAK_BYTES - 1] |= 0x10
if padded == 1 :
tweak[TWEAK_BYTES - 1] |= 0x40
if final_padded == 1 :
tweak[TWEAK_BYTES - 1] |= 0x50
return tweak
def TreatMessageEnc(M, N, key) :
checksum = [0 for byte in range(0, BLOCK_BYTES)]
l = int(M_BITS / BLOCK_BITS)
if int(M_BITS % BLOCK_BITS) > 0 :
will_padd = 1
else :
will_padd = 0
C = [[0 for byte in range(0, BLOCK_BYTES)] for j in range(0, l + will_padd)]
for j in range(0, l) :
checksum = XorState(checksum, M[j])
tweak = TweakMessage(N, j, padded = 0)
C[j] = ltbc.LilliputTBCEnc(tweak, key, M[j])
if will_padd == 0 :
tweak = TweakMessage(N, l, null = 1)
Final = ltbc.LilliputTBCEnc(tweak, key, checksum)
else :
m_padded = Padding10LSB(M[l], M_BITS % BLOCK_BITS)
checksum = XorState(checksum, m_padded)
tweak = TweakMessage(N, l, padded = 1)
pad = ltbc.LilliputTBCEnc(tweak, key, [0 for byte in range(0, BLOCK_BYTES)])
lower_part = LowPart(pad, M_BITS % BLOCK_BITS)
C[l] = XorState(M[l], lower_part)
tweak_final = TweakMessage(N, l+1, final_padded = 1)
Final = ltbc.LilliputTBCEnc(tweak_final, key, checksum)
return (Final, C)
def TreatMessageDec(C, N, key) :
checksum = [0 for byte in range(0, BLOCK_BYTES)]
l = int(M_BITS / BLOCK_BITS)
if int(M_BITS % BLOCK_BITS) > 0 :
will_padd = 1
else :
will_padd = 0
M = [[0 for byte in range(0, BLOCK_BYTES)] for j in range(0, l + will_padd)]
for j in range(0, l) :
tweak = TweakMessage(N, j, padded = 0)
M[j] = ltbc.LilliputTBCDec(tweak, key, C[j])
checksum = XorState(checksum, M[j])
if will_padd == 0 :
tweak = TweakMessage(N, l, null = 1)
Final = ltbc.LilliputTBCEnc(tweak, key, checksum)
else :
tweak = TweakMessage(N, l, padded = 1)
pad = ltbc.LilliputTBCEnc(tweak, key, [0 for byte in range(0, BLOCK_BYTES)])
lower_part = LowPart(pad, M_BITS % BLOCK_BITS)
M[l] = XorState(C[l], lower_part)
m_padded = Padding10LSB(M[l], M_BITS % BLOCK_BITS)
checksum = XorState(checksum, m_padded)
tweak_final = TweakMessage(N, l+1, final_padded = 1)
Final = ltbc.LilliputTBCEnc(tweak_final, key, checksum)
return (Final, M)
################################################################################
def OCB3Enc(A, M, N, key, tweak_bits, rounds) :
InitParameters(len(key)*8, tweak_bits, rounds)
global A_BITS
global M_BITS
A_BITS = len(A)*8
M_BITS = len(M)*8
A = ArrayToBlockbytesMatrix(A)
M = ArrayToBlockbytesMatrix(M)
ltbc.KEY_BITS = KEY_BITS
ltbc.ROUNDS = ROUNDS
ltbc.TWEAK_BITS = TWEAK_BITS
ltbc.LANES = LANES
ltbc.TWEAKEY_BITS = TWEAKEY_BITS
ltbc.KEY_BYTES = KEY_BYTES
ltbc.TWEAK_BYTES = TWEAK_BYTES
ltbc.TWEAKEY_BYTES = TWEAKEY_BYTES
ltbc.TKs = [[0 for byte in range(0, TWEAKEY_BYTES)] for round in range(0, ROUNDS)]
ltbc.RTKs = [[0 for byte in range(0, 8)] for round in range(0, ROUNDS)]
ltbc.States = [[0 for byte in range(0, BLOCK_BYTES)] for round in range(0, ROUNDS)]
Auth = BuildAuth(A, key)
(Final, C) = TreatMessageEnc(M, N, key)
tag = XorState(Auth, Final)
return BlockbytesMatrixToBytes(C), bytes(tag)
def OCB3Dec(A, C, N, tag, key, tweak_bits, rounds) :
InitParameters(len(key)*8, tweak_bits, rounds)
global A_BITS
global M_BITS
A_BITS = len(A)*8
M_BITS = len(C)*8
A = ArrayToBlockbytesMatrix(A)
C = ArrayToBlockbytesMatrix(C)
ltbc.KEY_BITS = KEY_BITS
ltbc.ROUNDS = ROUNDS
ltbc.TWEAK_BITS = TWEAK_BITS
ltbc.LANES = LANES
ltbc.TWEAKEY_BITS = TWEAKEY_BITS
ltbc.KEY_BYTES = KEY_BYTES
ltbc.TWEAK_BYTES = TWEAK_BYTES
ltbc.TWEAKEY_BYTES = TWEAKEY_BYTES
ltbc.TKs = [[0 for byte in range(0, TWEAKEY_BYTES)] for round in range(0, ROUNDS)]
ltbc.RTKs = [[0 for byte in range(0, 8)] for round in range(0, ROUNDS)]
ltbc.States = [[0 for byte in range(0, BLOCK_BYTES)] for round in range(0, ROUNDS)]
Auth = BuildAuth(A, key)
(Final, M) = TreatMessageDec(C, N, key)
tag2 = XorState(Auth, Final)
if(tag == tag2) :
return BlockbytesMatrixToBytes(M)
|
