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

   1 /*
   2  * Copyright (c) 2017 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_big_ctrcbc_init(br_aes_big_ctrcbc_keys *ctx,
  30         const void *key, size_t len)
  31 {
  32         ctx->vtable = &br_aes_big_ctrcbc_vtable;
  33         ctx->num_rounds = br_aes_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 void
  51 br_aes_big_ctrcbc_ctr(const br_aes_big_ctrcbc_keys *ctx,
  52         void *ctr, void *data, size_t len)
  53 {
  54         unsigned char *buf, *bctr;
  55         uint32_t cc0, cc1, cc2, cc3;
  56
  57         buf = data;
  58         bctr = ctr;
  59         cc3 = br_dec32be(bctr +  0);
  60         cc2 = br_dec32be(bctr +  4);
  61         cc1 = br_dec32be(bctr +  8);
  62         cc0 = br_dec32be(bctr + 12);
  63         while (len > 0) {
  64                 unsigned char tmp[16];
  65                 uint32_t carry;
  66
  67                 br_enc32be(tmp +  0, cc3);
  68                 br_enc32be(tmp +  4, cc2);
  69                 br_enc32be(tmp +  8, cc1);
  70                 br_enc32be(tmp + 12, cc0);
  71                 br_aes_big_encrypt(ctx->num_rounds, ctx->skey, tmp);
  72                 xorbuf(buf, tmp, 16);
  73                 buf += 16;
  74                 len -= 16;
  75                 cc0 ++;
  76                 carry = (~(cc0 | -cc0)) >> 31;
  77                 cc1 += carry;
  78                 carry &= (~(cc1 | -cc1)) >> 31;
  79                 cc2 += carry;
  80                 carry &= (~(cc2 | -cc2)) >> 31;
  81                 cc3 += carry;
  82         }
  83         br_enc32be(bctr +  0, cc3);
  84         br_enc32be(bctr +  4, cc2);
  85         br_enc32be(bctr +  8, cc1);
  86         br_enc32be(bctr + 12, cc0);
  87 }
  88
  89 /* see bearssl_block.h */
  90 void
  91 br_aes_big_ctrcbc_mac(const br_aes_big_ctrcbc_keys *ctx,
  92         void *cbcmac, const void *data, size_t len)
  93 {
  94         const unsigned char *buf;
  95
  96         buf = data;
  97         while (len > 0) {
  98                 xorbuf(cbcmac, buf, 16);
  99                 br_aes_big_encrypt(ctx->num_rounds, ctx->skey, cbcmac);
 100                 buf += 16;
 101                 len -= 16;
 102         }
 103 }
 104
 105 /* see bearssl_block.h */
 106 void
 107 br_aes_big_ctrcbc_encrypt(const br_aes_big_ctrcbc_keys *ctx,
 108         void *ctr, void *cbcmac, void *data, size_t len)
 109 {
 110         br_aes_big_ctrcbc_ctr(ctx, ctr, data, len);
 111         br_aes_big_ctrcbc_mac(ctx, cbcmac, data, len);
 112 }
 113
 114 /* see bearssl_block.h */
 115 void
 116 br_aes_big_ctrcbc_decrypt(const br_aes_big_ctrcbc_keys *ctx,
 117         void *ctr, void *cbcmac, void *data, size_t len)
 118 {
 119         br_aes_big_ctrcbc_mac(ctx, cbcmac, data, len);
 120         br_aes_big_ctrcbc_ctr(ctx, ctr, data, len);
 121 }
 122
 123 /* see bearssl_block.h */
 124 const br_block_ctrcbc_class br_aes_big_ctrcbc_vtable = {
 125         sizeof(br_aes_big_ctrcbc_keys),
 126         16,
 127         4,
 128         (void (*)(const br_block_ctrcbc_class **, const void *, size_t))
 129                 &br_aes_big_ctrcbc_init,
 130         (void (*)(const br_block_ctrcbc_class *const *,
 131                 void *, void *, void *, size_t))
 132                 &br_aes_big_ctrcbc_encrypt,
 133         (void (*)(const br_block_ctrcbc_class *const *,
 134                 void *, void *, void *, size_t))
 135                 &br_aes_big_ctrcbc_decrypt,
 136         (void (*)(const br_block_ctrcbc_class *const *,
 137                 void *, void *, size_t))
 138                 &br_aes_big_ctrcbc_ctr,
 139         (void (*)(const br_block_ctrcbc_class *const *,
 140                 void *, const void *, size_t))
 141                 &br_aes_big_ctrcbc_mac
 142 };