_ Git - BearSSL/blob - src/symcipher/aes_ct_cbcenc.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_ct_cbcenc_init(br_aes_ct_cbcenc_keys *ctx,
  30         const void *key, size_t len)
  31 {
  32         ctx->vtable = &br_aes_ct_cbcenc_vtable;
  33         ctx->num_rounds = br_aes_ct_keysched(ctx->skey, key, len);
  34 }
  35
  36 /* see bearssl_block.h */
  37 void
  38 br_aes_ct_cbcenc_run(const br_aes_ct_cbcenc_keys *ctx,
  39         void *iv, void *data, size_t len)
  40 {
  41         unsigned char *buf, *ivbuf;
  42         uint32_t q[8];
  43         uint32_t iv0, iv1, iv2, iv3;
  44         uint32_t sk_exp[120];
  45
  46         q[1] = 0;
  47         q[3] = 0;
  48         q[5] = 0;
  49         q[7] = 0;
  50         br_aes_ct_skey_expand(sk_exp, ctx->num_rounds, ctx->skey);
  51         ivbuf = iv;
  52         iv0 = br_dec32le(ivbuf);
  53         iv1 = br_dec32le(ivbuf + 4);
  54         iv2 = br_dec32le(ivbuf + 8);
  55         iv3 = br_dec32le(ivbuf + 12);
  56         buf = data;
  57         while (len > 0) {
  58                 q[0] = iv0 ^ br_dec32le(buf);
  59                 q[2] = iv1 ^ br_dec32le(buf + 4);
  60                 q[4] = iv2 ^ br_dec32le(buf + 8);
  61                 q[6] = iv3 ^ br_dec32le(buf + 12);
  62                 br_aes_ct_ortho(q);
  63                 br_aes_ct_bitslice_encrypt(ctx->num_rounds, sk_exp, q);
  64                 br_aes_ct_ortho(q);
  65                 iv0 = q[0];
  66                 iv1 = q[2];
  67                 iv2 = q[4];
  68                 iv3 = q[6];
  69                 br_enc32le(buf, iv0);
  70                 br_enc32le(buf + 4, iv1);
  71                 br_enc32le(buf + 8, iv2);
  72                 br_enc32le(buf + 12, iv3);
  73                 buf += 16;
  74                 len -= 16;
  75         }
  76         br_enc32le(ivbuf, iv0);
  77         br_enc32le(ivbuf + 4, iv1);
  78         br_enc32le(ivbuf + 8, iv2);
  79         br_enc32le(ivbuf + 12, iv3);
  80 }
  81
  82 /* see bearssl_block.h */
  83 const br_block_cbcenc_class br_aes_ct_cbcenc_vtable = {
  84         sizeof(br_aes_ct_cbcenc_keys),
  85         16,
  86         4,
  87         (void (*)(const br_block_cbcenc_class **, const void *, size_t))
  88                 &br_aes_ct_cbcenc_init,
  89         (void (*)(const br_block_cbcenc_class *const *, void *, void *, size_t))
  90                 &br_aes_ct_cbcenc_run
  91 };