1*0957b409SSimon J. Gerraty /*
2*0957b409SSimon J. Gerraty * Copyright (c) 2016 Thomas Pornin <pornin@bolet.org>
3*0957b409SSimon J. Gerraty *
4*0957b409SSimon J. Gerraty * Permission is hereby granted, free of charge, to any person obtaining
5*0957b409SSimon J. Gerraty * a copy of this software and associated documentation files (the
6*0957b409SSimon J. Gerraty * "Software"), to deal in the Software without restriction, including
7*0957b409SSimon J. Gerraty * without limitation the rights to use, copy, modify, merge, publish,
8*0957b409SSimon J. Gerraty * distribute, sublicense, and/or sell copies of the Software, and to
9*0957b409SSimon J. Gerraty * permit persons to whom the Software is furnished to do so, subject to
10*0957b409SSimon J. Gerraty * the following conditions:
11*0957b409SSimon J. Gerraty *
12*0957b409SSimon J. Gerraty * The above copyright notice and this permission notice shall be
13*0957b409SSimon J. Gerraty * included in all copies or substantial portions of the Software.
14*0957b409SSimon J. Gerraty *
15*0957b409SSimon J. Gerraty * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
16*0957b409SSimon J. Gerraty * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
17*0957b409SSimon J. Gerraty * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
18*0957b409SSimon J. Gerraty * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
19*0957b409SSimon J. Gerraty * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
20*0957b409SSimon J. Gerraty * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
21*0957b409SSimon J. Gerraty * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
22*0957b409SSimon J. Gerraty * SOFTWARE.
23*0957b409SSimon J. Gerraty */
24*0957b409SSimon J. Gerraty
25*0957b409SSimon J. Gerraty #include "inner.h"
26*0957b409SSimon J. Gerraty
27*0957b409SSimon J. Gerraty /* see inner.h */
28*0957b409SSimon J. Gerraty void
br_aes_ct_bitslice_invSbox(uint32_t * q)29*0957b409SSimon J. Gerraty br_aes_ct_bitslice_invSbox(uint32_t *q)
30*0957b409SSimon J. Gerraty {
31*0957b409SSimon J. Gerraty /*
32*0957b409SSimon J. Gerraty * AES S-box is:
33*0957b409SSimon J. Gerraty * S(x) = A(I(x)) ^ 0x63
34*0957b409SSimon J. Gerraty * where I() is inversion in GF(256), and A() is a linear
35*0957b409SSimon J. Gerraty * transform (0 is formally defined to be its own inverse).
36*0957b409SSimon J. Gerraty * Since inversion is an involution, the inverse S-box can be
37*0957b409SSimon J. Gerraty * computed from the S-box as:
38*0957b409SSimon J. Gerraty * iS(x) = B(S(B(x ^ 0x63)) ^ 0x63)
39*0957b409SSimon J. Gerraty * where B() is the inverse of A(). Indeed, for any y in GF(256):
40*0957b409SSimon J. Gerraty * iS(S(y)) = B(A(I(B(A(I(y)) ^ 0x63 ^ 0x63))) ^ 0x63 ^ 0x63) = y
41*0957b409SSimon J. Gerraty *
42*0957b409SSimon J. Gerraty * Note: we reuse the implementation of the forward S-box,
43*0957b409SSimon J. Gerraty * instead of duplicating it here, so that total code size is
44*0957b409SSimon J. Gerraty * lower. By merging the B() transforms into the S-box circuit
45*0957b409SSimon J. Gerraty * we could make faster CBC decryption, but CBC decryption is
46*0957b409SSimon J. Gerraty * already quite faster than CBC encryption because we can
47*0957b409SSimon J. Gerraty * process two blocks in parallel.
48*0957b409SSimon J. Gerraty */
49*0957b409SSimon J. Gerraty uint32_t q0, q1, q2, q3, q4, q5, q6, q7;
50*0957b409SSimon J. Gerraty
51*0957b409SSimon J. Gerraty q0 = ~q[0];
52*0957b409SSimon J. Gerraty q1 = ~q[1];
53*0957b409SSimon J. Gerraty q2 = q[2];
54*0957b409SSimon J. Gerraty q3 = q[3];
55*0957b409SSimon J. Gerraty q4 = q[4];
56*0957b409SSimon J. Gerraty q5 = ~q[5];
57*0957b409SSimon J. Gerraty q6 = ~q[6];
58*0957b409SSimon J. Gerraty q7 = q[7];
59*0957b409SSimon J. Gerraty q[7] = q1 ^ q4 ^ q6;
60*0957b409SSimon J. Gerraty q[6] = q0 ^ q3 ^ q5;
61*0957b409SSimon J. Gerraty q[5] = q7 ^ q2 ^ q4;
62*0957b409SSimon J. Gerraty q[4] = q6 ^ q1 ^ q3;
63*0957b409SSimon J. Gerraty q[3] = q5 ^ q0 ^ q2;
64*0957b409SSimon J. Gerraty q[2] = q4 ^ q7 ^ q1;
65*0957b409SSimon J. Gerraty q[1] = q3 ^ q6 ^ q0;
66*0957b409SSimon J. Gerraty q[0] = q2 ^ q5 ^ q7;
67*0957b409SSimon J. Gerraty
68*0957b409SSimon J. Gerraty br_aes_ct_bitslice_Sbox(q);
69*0957b409SSimon J. Gerraty
70*0957b409SSimon J. Gerraty q0 = ~q[0];
71*0957b409SSimon J. Gerraty q1 = ~q[1];
72*0957b409SSimon J. Gerraty q2 = q[2];
73*0957b409SSimon J. Gerraty q3 = q[3];
74*0957b409SSimon J. Gerraty q4 = q[4];
75*0957b409SSimon J. Gerraty q5 = ~q[5];
76*0957b409SSimon J. Gerraty q6 = ~q[6];
77*0957b409SSimon J. Gerraty q7 = q[7];
78*0957b409SSimon J. Gerraty q[7] = q1 ^ q4 ^ q6;
79*0957b409SSimon J. Gerraty q[6] = q0 ^ q3 ^ q5;
80*0957b409SSimon J. Gerraty q[5] = q7 ^ q2 ^ q4;
81*0957b409SSimon J. Gerraty q[4] = q6 ^ q1 ^ q3;
82*0957b409SSimon J. Gerraty q[3] = q5 ^ q0 ^ q2;
83*0957b409SSimon J. Gerraty q[2] = q4 ^ q7 ^ q1;
84*0957b409SSimon J. Gerraty q[1] = q3 ^ q6 ^ q0;
85*0957b409SSimon J. Gerraty q[0] = q2 ^ q5 ^ q7;
86*0957b409SSimon J. Gerraty }
87*0957b409SSimon J. Gerraty
88*0957b409SSimon J. Gerraty static void
add_round_key(uint32_t * q,const uint32_t * sk)89*0957b409SSimon J. Gerraty add_round_key(uint32_t *q, const uint32_t *sk)
90*0957b409SSimon J. Gerraty {
91*0957b409SSimon J. Gerraty int i;
92*0957b409SSimon J. Gerraty
93*0957b409SSimon J. Gerraty for (i = 0; i < 8; i ++) {
94*0957b409SSimon J. Gerraty q[i] ^= sk[i];
95*0957b409SSimon J. Gerraty }
96*0957b409SSimon J. Gerraty }
97*0957b409SSimon J. Gerraty
98*0957b409SSimon J. Gerraty static void
inv_shift_rows(uint32_t * q)99*0957b409SSimon J. Gerraty inv_shift_rows(uint32_t *q)
100*0957b409SSimon J. Gerraty {
101*0957b409SSimon J. Gerraty int i;
102*0957b409SSimon J. Gerraty
103*0957b409SSimon J. Gerraty for (i = 0; i < 8; i ++) {
104*0957b409SSimon J. Gerraty uint32_t x;
105*0957b409SSimon J. Gerraty
106*0957b409SSimon J. Gerraty x = q[i];
107*0957b409SSimon J. Gerraty q[i] = (x & 0x000000FF)
108*0957b409SSimon J. Gerraty | ((x & 0x00003F00) << 2) | ((x & 0x0000C000) >> 6)
109*0957b409SSimon J. Gerraty | ((x & 0x000F0000) << 4) | ((x & 0x00F00000) >> 4)
110*0957b409SSimon J. Gerraty | ((x & 0x03000000) << 6) | ((x & 0xFC000000) >> 2);
111*0957b409SSimon J. Gerraty }
112*0957b409SSimon J. Gerraty }
113*0957b409SSimon J. Gerraty
114*0957b409SSimon J. Gerraty static inline uint32_t
rotr16(uint32_t x)115*0957b409SSimon J. Gerraty rotr16(uint32_t x)
116*0957b409SSimon J. Gerraty {
117*0957b409SSimon J. Gerraty return (x << 16) | (x >> 16);
118*0957b409SSimon J. Gerraty }
119*0957b409SSimon J. Gerraty
120*0957b409SSimon J. Gerraty static void
inv_mix_columns(uint32_t * q)121*0957b409SSimon J. Gerraty inv_mix_columns(uint32_t *q)
122*0957b409SSimon J. Gerraty {
123*0957b409SSimon J. Gerraty uint32_t q0, q1, q2, q3, q4, q5, q6, q7;
124*0957b409SSimon J. Gerraty uint32_t r0, r1, r2, r3, r4, r5, r6, r7;
125*0957b409SSimon J. Gerraty
126*0957b409SSimon J. Gerraty q0 = q[0];
127*0957b409SSimon J. Gerraty q1 = q[1];
128*0957b409SSimon J. Gerraty q2 = q[2];
129*0957b409SSimon J. Gerraty q3 = q[3];
130*0957b409SSimon J. Gerraty q4 = q[4];
131*0957b409SSimon J. Gerraty q5 = q[5];
132*0957b409SSimon J. Gerraty q6 = q[6];
133*0957b409SSimon J. Gerraty q7 = q[7];
134*0957b409SSimon J. Gerraty r0 = (q0 >> 8) | (q0 << 24);
135*0957b409SSimon J. Gerraty r1 = (q1 >> 8) | (q1 << 24);
136*0957b409SSimon J. Gerraty r2 = (q2 >> 8) | (q2 << 24);
137*0957b409SSimon J. Gerraty r3 = (q3 >> 8) | (q3 << 24);
138*0957b409SSimon J. Gerraty r4 = (q4 >> 8) | (q4 << 24);
139*0957b409SSimon J. Gerraty r5 = (q5 >> 8) | (q5 << 24);
140*0957b409SSimon J. Gerraty r6 = (q6 >> 8) | (q6 << 24);
141*0957b409SSimon J. Gerraty r7 = (q7 >> 8) | (q7 << 24);
142*0957b409SSimon J. Gerraty
143*0957b409SSimon J. Gerraty q[0] = q5 ^ q6 ^ q7 ^ r0 ^ r5 ^ r7 ^ rotr16(q0 ^ q5 ^ q6 ^ r0 ^ r5);
144*0957b409SSimon J. Gerraty q[1] = q0 ^ q5 ^ r0 ^ r1 ^ r5 ^ r6 ^ r7 ^ rotr16(q1 ^ q5 ^ q7 ^ r1 ^ r5 ^ r6);
145*0957b409SSimon J. Gerraty q[2] = q0 ^ q1 ^ q6 ^ r1 ^ r2 ^ r6 ^ r7 ^ rotr16(q0 ^ q2 ^ q6 ^ r2 ^ r6 ^ r7);
146*0957b409SSimon J. Gerraty q[3] = q0 ^ q1 ^ q2 ^ q5 ^ q6 ^ r0 ^ r2 ^ r3 ^ r5 ^ rotr16(q0 ^ q1 ^ q3 ^ q5 ^ q6 ^ q7 ^ r0 ^ r3 ^ r5 ^ r7);
147*0957b409SSimon J. Gerraty q[4] = q1 ^ q2 ^ q3 ^ q5 ^ r1 ^ r3 ^ r4 ^ r5 ^ r6 ^ r7 ^ rotr16(q1 ^ q2 ^ q4 ^ q5 ^ q7 ^ r1 ^ r4 ^ r5 ^ r6);
148*0957b409SSimon J. Gerraty q[5] = q2 ^ q3 ^ q4 ^ q6 ^ r2 ^ r4 ^ r5 ^ r6 ^ r7 ^ rotr16(q2 ^ q3 ^ q5 ^ q6 ^ r2 ^ r5 ^ r6 ^ r7);
149*0957b409SSimon J. Gerraty q[6] = q3 ^ q4 ^ q5 ^ q7 ^ r3 ^ r5 ^ r6 ^ r7 ^ rotr16(q3 ^ q4 ^ q6 ^ q7 ^ r3 ^ r6 ^ r7);
150*0957b409SSimon J. Gerraty q[7] = q4 ^ q5 ^ q6 ^ r4 ^ r6 ^ r7 ^ rotr16(q4 ^ q5 ^ q7 ^ r4 ^ r7);
151*0957b409SSimon J. Gerraty }
152*0957b409SSimon J. Gerraty
153*0957b409SSimon J. Gerraty /* see inner.h */
154*0957b409SSimon J. Gerraty void
br_aes_ct_bitslice_decrypt(unsigned num_rounds,const uint32_t * skey,uint32_t * q)155*0957b409SSimon J. Gerraty br_aes_ct_bitslice_decrypt(unsigned num_rounds,
156*0957b409SSimon J. Gerraty const uint32_t *skey, uint32_t *q)
157*0957b409SSimon J. Gerraty {
158*0957b409SSimon J. Gerraty unsigned u;
159*0957b409SSimon J. Gerraty
160*0957b409SSimon J. Gerraty add_round_key(q, skey + (num_rounds << 3));
161*0957b409SSimon J. Gerraty for (u = num_rounds - 1; u > 0; u --) {
162*0957b409SSimon J. Gerraty inv_shift_rows(q);
163*0957b409SSimon J. Gerraty br_aes_ct_bitslice_invSbox(q);
164*0957b409SSimon J. Gerraty add_round_key(q, skey + (u << 3));
165*0957b409SSimon J. Gerraty inv_mix_columns(q);
166*0957b409SSimon J. Gerraty }
167*0957b409SSimon J. Gerraty inv_shift_rows(q);
168*0957b409SSimon J. Gerraty br_aes_ct_bitslice_invSbox(q);
169*0957b409SSimon J. Gerraty add_round_key(q, skey);
170*0957b409SSimon J. Gerraty }
171