1/*
2 * Copyright (c) 2016 Thomas Pornin <pornin@bolet.org>
3 *
4 * Permission is hereby granted, free of charge, to any person obtaining
5 * a copy of this software and associated documentation files (the
6 * "Software"), to deal in the Software without restriction, including
7 * without limitation the rights to use, copy, modify, merge, publish,
8 * distribute, sublicense, and/or sell copies of the Software, and to
9 * permit persons to whom the Software is furnished to do so, subject to
10 * the following conditions:
11 *
12 * The above copyright notice and this permission notice shall be
13 * included in all copies or substantial portions of the Software.
14 *
15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
16 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
17 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
18 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
19 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
20 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
21 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
22 * SOFTWARE.
23 */
24
25#include "inner.h"
26
27/* see inner.h */
28void
29br_aes_ct_bitslice_Sbox(uint32_t *q)
30{
31	/*
32	 * This S-box implementation is a straightforward translation of
33	 * the circuit described by Boyar and Peralta in "A new
34	 * combinational logic minimization technique with applications
35	 * to cryptology" (https://eprint.iacr.org/2009/191.pdf).
36	 *
37	 * Note that variables x* (input) and s* (output) are numbered
38	 * in "reverse" order (x0 is the high bit, x7 is the low bit).
39	 */
40
41	uint32_t x0, x1, x2, x3, x4, x5, x6, x7;
42	uint32_t y1, y2, y3, y4, y5, y6, y7, y8, y9;
43	uint32_t y10, y11, y12, y13, y14, y15, y16, y17, y18, y19;
44	uint32_t y20, y21;
45	uint32_t z0, z1, z2, z3, z4, z5, z6, z7, z8, z9;
46	uint32_t z10, z11, z12, z13, z14, z15, z16, z17;
47	uint32_t t0, t1, t2, t3, t4, t5, t6, t7, t8, t9;
48	uint32_t t10, t11, t12, t13, t14, t15, t16, t17, t18, t19;
49	uint32_t t20, t21, t22, t23, t24, t25, t26, t27, t28, t29;
50	uint32_t t30, t31, t32, t33, t34, t35, t36, t37, t38, t39;
51	uint32_t t40, t41, t42, t43, t44, t45, t46, t47, t48, t49;
52	uint32_t t50, t51, t52, t53, t54, t55, t56, t57, t58, t59;
53	uint32_t t60, t61, t62, t63, t64, t65, t66, t67;
54	uint32_t s0, s1, s2, s3, s4, s5, s6, s7;
55
56	x0 = q[7];
57	x1 = q[6];
58	x2 = q[5];
59	x3 = q[4];
60	x4 = q[3];
61	x5 = q[2];
62	x6 = q[1];
63	x7 = q[0];
64
65	/*
66	 * Top linear transformation.
67	 */
68	y14 = x3 ^ x5;
69	y13 = x0 ^ x6;
70	y9 = x0 ^ x3;
71	y8 = x0 ^ x5;
72	t0 = x1 ^ x2;
73	y1 = t0 ^ x7;
74	y4 = y1 ^ x3;
75	y12 = y13 ^ y14;
76	y2 = y1 ^ x0;
77	y5 = y1 ^ x6;
78	y3 = y5 ^ y8;
79	t1 = x4 ^ y12;
80	y15 = t1 ^ x5;
81	y20 = t1 ^ x1;
82	y6 = y15 ^ x7;
83	y10 = y15 ^ t0;
84	y11 = y20 ^ y9;
85	y7 = x7 ^ y11;
86	y17 = y10 ^ y11;
87	y19 = y10 ^ y8;
88	y16 = t0 ^ y11;
89	y21 = y13 ^ y16;
90	y18 = x0 ^ y16;
91
92	/*
93	 * Non-linear section.
94	 */
95	t2 = y12 & y15;
96	t3 = y3 & y6;
97	t4 = t3 ^ t2;
98	t5 = y4 & x7;
99	t6 = t5 ^ t2;
100	t7 = y13 & y16;
101	t8 = y5 & y1;
102	t9 = t8 ^ t7;
103	t10 = y2 & y7;
104	t11 = t10 ^ t7;
105	t12 = y9 & y11;
106	t13 = y14 & y17;
107	t14 = t13 ^ t12;
108	t15 = y8 & y10;
109	t16 = t15 ^ t12;
110	t17 = t4 ^ t14;
111	t18 = t6 ^ t16;
112	t19 = t9 ^ t14;
113	t20 = t11 ^ t16;
114	t21 = t17 ^ y20;
115	t22 = t18 ^ y19;
116	t23 = t19 ^ y21;
117	t24 = t20 ^ y18;
118
119	t25 = t21 ^ t22;
120	t26 = t21 & t23;
121	t27 = t24 ^ t26;
122	t28 = t25 & t27;
123	t29 = t28 ^ t22;
124	t30 = t23 ^ t24;
125	t31 = t22 ^ t26;
126	t32 = t31 & t30;
127	t33 = t32 ^ t24;
128	t34 = t23 ^ t33;
129	t35 = t27 ^ t33;
130	t36 = t24 & t35;
131	t37 = t36 ^ t34;
132	t38 = t27 ^ t36;
133	t39 = t29 & t38;
134	t40 = t25 ^ t39;
135
136	t41 = t40 ^ t37;
137	t42 = t29 ^ t33;
138	t43 = t29 ^ t40;
139	t44 = t33 ^ t37;
140	t45 = t42 ^ t41;
141	z0 = t44 & y15;
142	z1 = t37 & y6;
143	z2 = t33 & x7;
144	z3 = t43 & y16;
145	z4 = t40 & y1;
146	z5 = t29 & y7;
147	z6 = t42 & y11;
148	z7 = t45 & y17;
149	z8 = t41 & y10;
150	z9 = t44 & y12;
151	z10 = t37 & y3;
152	z11 = t33 & y4;
153	z12 = t43 & y13;
154	z13 = t40 & y5;
155	z14 = t29 & y2;
156	z15 = t42 & y9;
157	z16 = t45 & y14;
158	z17 = t41 & y8;
159
160	/*
161	 * Bottom linear transformation.
162	 */
163	t46 = z15 ^ z16;
164	t47 = z10 ^ z11;
165	t48 = z5 ^ z13;
166	t49 = z9 ^ z10;
167	t50 = z2 ^ z12;
168	t51 = z2 ^ z5;
169	t52 = z7 ^ z8;
170	t53 = z0 ^ z3;
171	t54 = z6 ^ z7;
172	t55 = z16 ^ z17;
173	t56 = z12 ^ t48;
174	t57 = t50 ^ t53;
175	t58 = z4 ^ t46;
176	t59 = z3 ^ t54;
177	t60 = t46 ^ t57;
178	t61 = z14 ^ t57;
179	t62 = t52 ^ t58;
180	t63 = t49 ^ t58;
181	t64 = z4 ^ t59;
182	t65 = t61 ^ t62;
183	t66 = z1 ^ t63;
184	s0 = t59 ^ t63;
185	s6 = t56 ^ ~t62;
186	s7 = t48 ^ ~t60;
187	t67 = t64 ^ t65;
188	s3 = t53 ^ t66;
189	s4 = t51 ^ t66;
190	s5 = t47 ^ t65;
191	s1 = t64 ^ ~s3;
192	s2 = t55 ^ ~t67;
193
194	q[7] = s0;
195	q[6] = s1;
196	q[5] = s2;
197	q[4] = s3;
198	q[3] = s4;
199	q[2] = s5;
200	q[1] = s6;
201	q[0] = s7;
202}
203
204/* see inner.h */
205void
206br_aes_ct_ortho(uint32_t *q)
207{
208#define SWAPN(cl, ch, s, x, y)   do { \
209		uint32_t a, b; \
210		a = (x); \
211		b = (y); \
212		(x) = (a & (uint32_t)cl) | ((b & (uint32_t)cl) << (s)); \
213		(y) = ((a & (uint32_t)ch) >> (s)) | (b & (uint32_t)ch); \
214	} while (0)
215
216#define SWAP2(x, y)   SWAPN(0x55555555, 0xAAAAAAAA, 1, x, y)
217#define SWAP4(x, y)   SWAPN(0x33333333, 0xCCCCCCCC, 2, x, y)
218#define SWAP8(x, y)   SWAPN(0x0F0F0F0F, 0xF0F0F0F0, 4, x, y)
219
220	SWAP2(q[0], q[1]);
221	SWAP2(q[2], q[3]);
222	SWAP2(q[4], q[5]);
223	SWAP2(q[6], q[7]);
224
225	SWAP4(q[0], q[2]);
226	SWAP4(q[1], q[3]);
227	SWAP4(q[4], q[6]);
228	SWAP4(q[5], q[7]);
229
230	SWAP8(q[0], q[4]);
231	SWAP8(q[1], q[5]);
232	SWAP8(q[2], q[6]);
233	SWAP8(q[3], q[7]);
234}
235
236static const unsigned char Rcon[] = {
237	0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1B, 0x36
238};
239
240static uint32_t
241sub_word(uint32_t x)
242{
243	uint32_t q[8];
244	int i;
245
246	for (i = 0; i < 8; i ++) {
247		q[i] = x;
248	}
249	br_aes_ct_ortho(q);
250	br_aes_ct_bitslice_Sbox(q);
251	br_aes_ct_ortho(q);
252	return q[0];
253}
254
255/* see inner.h */
256unsigned
257br_aes_ct_keysched(uint32_t *comp_skey, const void *key, size_t key_len)
258{
259	unsigned num_rounds;
260	int i, j, k, nk, nkf;
261	uint32_t tmp;
262	uint32_t skey[120];
263
264	switch (key_len) {
265	case 16:
266		num_rounds = 10;
267		break;
268	case 24:
269		num_rounds = 12;
270		break;
271	case 32:
272		num_rounds = 14;
273		break;
274	default:
275		/* abort(); */
276		return 0;
277	}
278	nk = (int)(key_len >> 2);
279	nkf = (int)((num_rounds + 1) << 2);
280	tmp = 0;
281	for (i = 0; i < nk; i ++) {
282		tmp = br_dec32le((const unsigned char *)key + (i << 2));
283		skey[(i << 1) + 0] = tmp;
284		skey[(i << 1) + 1] = tmp;
285	}
286	for (i = nk, j = 0, k = 0; i < nkf; i ++) {
287		if (j == 0) {
288			tmp = (tmp << 24) | (tmp >> 8);
289			tmp = sub_word(tmp) ^ Rcon[k];
290		} else if (nk > 6 && j == 4) {
291			tmp = sub_word(tmp);
292		}
293		tmp ^= skey[(i - nk) << 1];
294		skey[(i << 1) + 0] = tmp;
295		skey[(i << 1) + 1] = tmp;
296		if (++ j == nk) {
297			j = 0;
298			k ++;
299		}
300	}
301	for (i = 0; i < nkf; i += 4) {
302		br_aes_ct_ortho(skey + (i << 1));
303	}
304	for (i = 0, j = 0; i < nkf; i ++, j += 2) {
305		comp_skey[i] = (skey[j + 0] & 0x55555555)
306			| (skey[j + 1] & 0xAAAAAAAA);
307	}
308	return num_rounds;
309}
310
311/* see inner.h */
312void
313br_aes_ct_skey_expand(uint32_t *skey,
314	unsigned num_rounds, const uint32_t *comp_skey)
315{
316	unsigned u, v, n;
317
318	n = (num_rounds + 1) << 2;
319	for (u = 0, v = 0; u < n; u ++, v += 2) {
320		uint32_t x, y;
321
322		x = y = comp_skey[u];
323		x &= 0x55555555;
324		skey[v + 0] = x | (x << 1);
325		y &= 0xAAAAAAAA;
326		skey[v + 1] = y | (y >> 1);
327	}
328}
329