_ Git - BearSSL/blob - src/symcipher/aes_ct.c

   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 */
  28 void
  29 br_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 */
 205 void
 206 br_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
 236 static const unsigned char Rcon[] = {
 237         0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1B, 0x36
 238 };
 239
 240 static uint32_t
 241 sub_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 */
 256 unsigned
 257 br_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 */
 312 void
 313 br_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 }