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
|
; Copyright (c) 2015 Egor Tensin <Egor.Tensin@gmail.com>
; This file is part of the "AES tools" project.
; For details, see https://github.com/egor-tensin/aes-tools.
; Distributed under the MIT License.
.586
.xmm
.model flat
.code
@aes_AES128_encrypt_block_@20 proc
pxor xmm0, [ecx]
aesenc xmm0, [ecx + 10h]
aesenc xmm0, [ecx + 20h]
aesenc xmm0, [ecx + 30h]
aesenc xmm0, [ecx + 40h]
aesenc xmm0, [ecx + 50h]
aesenc xmm0, [ecx + 60h]
aesenc xmm0, [ecx + 70h]
aesenc xmm0, [ecx + 80h]
aesenc xmm0, [ecx + 90h]
aesenclast xmm0, [ecx + 0A0h]
ret
@aes_AES128_encrypt_block_@20 endp
@aes_AES128_decrypt_block_@20 proc
pxor xmm0, [ecx]
aesdec xmm0, [ecx + 10h]
aesdec xmm0, [ecx + 20h]
aesdec xmm0, [ecx + 30h]
aesdec xmm0, [ecx + 40h]
aesdec xmm0, [ecx + 50h]
aesdec xmm0, [ecx + 60h]
aesdec xmm0, [ecx + 70h]
aesdec xmm0, [ecx + 80h]
aesdec xmm0, [ecx + 90h]
aesdeclast xmm0, [ecx + 0A0h]
ret
@aes_AES128_decrypt_block_@20 endp
@aes_AES128_expand_key_@20 proc
; A "word" (in terms of the FIPS 187 standard) is a 32-bit block.
; Words are denoted by `w[N]`.
;
; A key schedule is composed of 10 "regular" keys and a dumb key for
; the "whitening" step.
;
; A key schedule is thus composed of 44 "words".
; The FIPS standard includes an algorithm to calculate these words via
; a simple loop:
;
; i = 4
; while i < 44:
; temp = w[i - 1]
; if i % 4 == 0:
; temp = SubWord(RotWord(temp))^Rcon
; w[i] = w[i - 4]^temp
; i = i + 1
;
; The loop above may be unrolled like this:
;
; w[4] = SubWord(RotWord(w[3]))^Rcon^w[0]
; w[5] = w[4]^w[1]
; = SubWord(RotWord(w[3]))^Rcon^w[1]^w[0]
; w[6] = w[5]^w[2]
; = SubWord(RotWord(w[3]))^Rcon^w[2]^w[1]^w[0]
; w[7] = w[6]^w[3]
; = SubWord(RotWord(w[3]))^Rcon^w[3]^w[2]^w[1]^w[0]
; w[8] = SubWord(RotWord(w[7]))^Rcon^w[4]
; w[9] = w[8]^w[5]
; = SubWord(RotWord(w[7]))^Rcon^w[5]^w[4]
; w[10] = w[9]^w[6]
; = SubWord(RotWord(w[7]))^Rcon^w[6]^w[5]^w[4]
; w[11] = w[10]^w[7]
; = SubWord(RotWord(w[7]))^Rcon^w[7]^w[6]^w[5]^w[4]
;
; ... and so on.
;
; The Intel AES-NI instruction set facilitates calculating SubWord
; and RotWord using `aeskeygenassist`, which is used in this routine.
;
; Preconditions:
; * xmm0[127:96] == w[3],
; * xmm0[95:64] == w[2],
; * xmm0[63:32] == w[1],
; * xmm0[31:0] == w[0].
movdqa [ecx], xmm0 ; sets w[0], w[1], w[2], w[3]
add ecx, 10h ; ecx = &w[4]
aeskeygenassist xmm5, xmm0, 01h ; xmm5[127:96] = RotWord(SubWord(w[3]))^Rcon
call aes128_keygen_assist ; sets w[4], w[5], w[6], w[7]
aeskeygenassist xmm5, xmm0, 02h ; xmm5[127:96] = RotWord(SubWord(w[7]))^Rcon
call aes128_keygen_assist ; sets w[8], w[9], w[10], w[11]
aeskeygenassist xmm5, xmm0, 04h ; xmm5[127:96] = RotWord(SubWord(w[11]))^Rcon
call aes128_keygen_assist ; sets w[12], w[13], w[14], w[15]
aeskeygenassist xmm5, xmm0, 08h ; xmm5[127:96] = RotWord(SubWord(w[15]))^Rcon
call aes128_keygen_assist ; sets w[16], w[17], w[18], w[19]
aeskeygenassist xmm5, xmm0, 10h ; xmm5[127:96] = RotWord(SubWord(w[19]))^Rcon
call aes128_keygen_assist ; sets w[20], w[21], w[22], w[23]
aeskeygenassist xmm5, xmm0, 20h ; xmm5[127:96] = RotWord(SubWord(w[23]))^Rcon
call aes128_keygen_assist ; sets w[24], w[25], w[26], w[27]
aeskeygenassist xmm5, xmm0, 40h ; xmm5[127:96] = RotWord(SubWord(w[27]))^Rcon
call aes128_keygen_assist ; sets w[28], w[29], w[30], w[31]
aeskeygenassist xmm5, xmm0, 80h ; xmm5[127:96] = RotWord(SubWord(w[31]))^Rcon
call aes128_keygen_assist ; sets w[32], w[33], w[34], w[35]
aeskeygenassist xmm5, xmm0, 1Bh ; xmm5[127:96] = RotWord(SubWord(w[35]))^Rcon
call aes128_keygen_assist ; sets w[36], w[37], w[38], w[39]
aeskeygenassist xmm5, xmm0, 36h ; xmm5[127:96] = RotWord(SubWord(w[39]))^Rcon
call aes128_keygen_assist ; sets w[40], w[41], w[42], w[43]
ret
aes128_keygen_assist:
; Preconditions:
; * xmm0[127:96] == w[i+3],
; * xmm0[95:64] == w[i+2],
; * xmm0[63:32] == w[i+1],
; * xmm0[31:0] == w[i],
; * xmm5[127:96] == RotWord(SubWord(w[i+3]))^Rcon,
; * ecx == &w[i+4].
;
; Postconditions:
; * xmm0[127:96] == w[i+7] == RotWord(SubWord(w[i+3]))^Rcon^w[i+3]^w[i+2]^w[i+1]^w[i],
; * xmm0[95:64] == w[i+6] == RotWord(SubWord(w[i+3]))^Rcon^w[i+2]^w[i+1]^w[i],
; * xmm0[63:32] == w[i+5] == RotWord(SubWord(w[i+3]))^Rcon^w[i+1]^w[i],
; * xmm0[31:0] == w[i+4] == RotWord(SubWord(w[i+3]))^Rcon^w[i],
; * ecx == &w[i+8],
; * the value in xmm4 is also modified.
; Calculate
; w[i+3]^w[i+2]^w[i+1]^w[i],
; w[i+2]^w[i+1]^w[i],
; w[i+1]^w[i] and
; w[i].
movdqa xmm4, xmm0 ; xmm4 = xmm0
pslldq xmm4, 4 ; xmm4 <<= 32
pxor xmm0, xmm4 ; xmm0 ^= xmm4
pslldq xmm4, 4 ; xmm4 <<= 32
pxor xmm0, xmm4 ; xmm0 ^= xmm4
pslldq xmm4, 4 ; xmm4 <<= 32
pxor xmm0, xmm4 ; xmm0 ^= xmm4
; xmm0[127:96] == w[i+3]^w[i+2]^w[i+1]^w[i]
; xmm0[95:64] == w[i+2]^w[i+1]^w[i]
; xmm0[63:32] == w[i+1]^w[i]
; xmm0[31:0] == w[i]
; Calculate
; w[i+7] == RotWord(SubWord(w[i+3]))^Rcon^w[i+3]^w[i+2]^w[i+1]^w[i],
; w[i+6] == RotWord(SubWord(w[i+3]))^Rcon^w[i+2]^w[i+1]^w[i],
; w[i+5] == RotWord(SubWord(w[i+3]))^Rcon^w[i+1]^w[i] and
; w[i+4] == RotWord(SubWord(w[i+3]))^Rcon^w[i].
pshufd xmm4, xmm5, 0FFh ; xmm4[127:96] = xmm4[95:64] = xmm4[63:32] = xmm4[31:0] = xmm5[127:96]
pxor xmm0, xmm4 ; xmm0 ^= xmm4
; xmm0[127:96] == w[i+7] == RotWord(SubWord(w[i+3]))^Rcon^w[i+3]^w[i+2]^w[i+1]^w[i]
; xmm0[95:64] == w[i+6] == RotWord(SubWord(w[i+3]))^Rcon^w[i+2]^w[i+1]^w[i]
; xmm0[63:32] == w[i+5] == RotWord(SubWord(w[i+3]))^Rcon^w[i+1]^w[i]
; xmm0[31:0] == w[i+4] == RotWord(SubWord(w[i+3]))^Rcon^w[i]
; Set w[i+4], w[i+5], w[i+6] and w[i+7].
movdqa [ecx], xmm0 ; w[i+7] = RotWord(SubWord(w[i+3]))^Rcon^w[i+3]^w[i+2]^w[i+1]^w[i]
; w[i+6] = RotWord(SubWord(w[i+3]))^Rcon^w[i+2]^w[i+1]^w[i]
; w[i+5] = RotWord(SubWord(w[i+3]))^Rcon^w[i+1]^w[i]
; w[i+4] = RotWord(SubWord(w[i+3]))^Rcon^w[i]
add ecx, 10h ; ecx = &w[i+8]
ret
@aes_AES128_expand_key_@20 endp
@aes_AES128_derive_decryption_keys_@8 proc
movdqa xmm5, [ecx]
movdqa xmm4, [ecx + 0A0h]
movdqa [edx], xmm4
movdqa [edx + 0A0h], xmm5
aesimc xmm5, [ecx + 10h]
aesimc xmm4, [ecx + 90h]
movdqa [edx + 10h], xmm4
movdqa [edx + 90h], xmm5
aesimc xmm5, [ecx + 20h]
aesimc xmm4, [ecx + 80h]
movdqa [edx + 20h], xmm4
movdqa [edx + 80h], xmm5
aesimc xmm5, [ecx + 30h]
aesimc xmm4, [ecx + 70h]
movdqa [edx + 30h], xmm4
movdqa [edx + 70h], xmm5
aesimc xmm5, [ecx + 40h]
aesimc xmm4, [ecx + 60h]
movdqa [edx + 40h], xmm4
movdqa [edx + 60h], xmm5
aesimc xmm5, [ecx + 50h]
movdqa [edx + 50h], xmm5
ret
@aes_AES128_derive_decryption_keys_@8 endp
end
|
