_ Git - BearSSL/blob - src/symcipher/aes_ct64_ctr.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 bearssl_block.h */
  28 void
  29 br_aes_ct64_ctr_init(br_aes_ct64_ctr_keys *ctx,
  30         const void *key, size_t len)
  31 {
  32         ctx->vtable = &br_aes_ct64_ctr_vtable;
  33         ctx->num_rounds = br_aes_ct64_keysched(ctx->skey, key, len);
  34 }
  35
  36 static void
  37 xorbuf(void *dst, const void *src, size_t len)
  38 {
  39         unsigned char *d;
  40         const unsigned char *s;
  41
  42         d = dst;
  43         s = src;
  44         while (len -- > 0) {
  45                 *d ++ ^= *s ++;
  46         }
  47 }
  48
  49 /* see bearssl_block.h */
  50 uint32_t
  51 br_aes_ct64_ctr_run(const br_aes_ct64_ctr_keys *ctx,
  52         const void *iv, uint32_t cc, void *data, size_t len)
  53 {
  54         unsigned char *buf;
  55         uint32_t ivw[16];
  56         uint64_t sk_exp[120];
  57
  58         br_aes_ct64_skey_expand(sk_exp, ctx->num_rounds, ctx->skey);
  59         br_range_dec32le(ivw, 3, iv);
  60         memcpy(ivw + 4, ivw, 3 * sizeof(uint32_t));
  61         memcpy(ivw + 8, ivw, 3 * sizeof(uint32_t));
  62         memcpy(ivw + 12, ivw, 3 * sizeof(uint32_t));
  63         buf = data;
  64         while (len > 0) {
  65                 uint64_t q[8];
  66                 uint32_t w[16];
  67                 unsigned char tmp[64];
  68                 int i;
  69
  70                 /*
  71                  * TODO: see if we can save on the first br_aes_ct64_ortho()
  72                  * call, since iv0/iv1/iv2 are constant for the whole run.
  73                  */
  74                 memcpy(w, ivw, sizeof ivw);
  75                 w[3] = br_swap32(cc);
  76                 w[7] = br_swap32(cc + 1);
  77                 w[11] = br_swap32(cc + 2);
  78                 w[15] = br_swap32(cc + 3);
  79                 for (i = 0; i < 4; i ++) {
  80                         br_aes_ct64_interleave_in(
  81                                 &q[i], &q[i + 4], w + (i << 2));
  82                 }
  83                 br_aes_ct64_ortho(q);
  84                 br_aes_ct64_bitslice_encrypt(ctx->num_rounds, sk_exp, q);
  85                 br_aes_ct64_ortho(q);
  86                 for (i = 0; i < 4; i ++) {
  87                         br_aes_ct64_interleave_out(
  88                                 w + (i << 2), q[i], q[i + 4]);
  89                 }
  90                 br_range_enc32le(tmp, w, 16);
  91                 if (len <= 64) {
  92                         xorbuf(buf, tmp, len);
  93                         cc += (uint32_t)len >> 4;
  94                         break;
  95                 }
  96                 xorbuf(buf, tmp, 64);
  97                 buf += 64;
  98                 len -= 64;
  99                 cc += 4;
 100         }
 101         return cc;
 102 }
 103
 104 /* see bearssl_block.h */
 105 const br_block_ctr_class br_aes_ct64_ctr_vtable = {
 106         sizeof(br_aes_ct64_ctr_keys),
 107         16,
 108         4,
 109         (void (*)(const br_block_ctr_class **, const void *, size_t))
 110                 &br_aes_ct64_ctr_init,
 111         (uint32_t (*)(const br_block_ctr_class *const *,
 112                 const void *, uint32_t, void *, size_t))
 113                 &br_aes_ct64_ctr_run
 114 };