_ Git - BearSSL/blob - src/mac/hmac.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 static inline size_t
  28 block_size(const br_hash_class *dig)
  29 {
  30         unsigned ls;
  31
  32         ls = (unsigned)(dig->desc >> BR_HASHDESC_LBLEN_OFF)
  33                 & BR_HASHDESC_LBLEN_MASK;
  34         return (size_t)1 << ls;
  35 }
  36
  37 static void
  38 process_key(const br_hash_class **hc, void *ks,
  39         const void *key, size_t key_len, unsigned bb)
  40 {
  41         unsigned char tmp[256];
  42         size_t blen, u;
  43
  44         blen = block_size(*hc);
  45         memcpy(tmp, key, key_len);
  46         for (u = 0; u < key_len; u ++) {
  47                 tmp[u] ^= (unsigned char)bb;
  48         }
  49         memset(tmp + key_len, bb, blen - key_len);
  50         (*hc)->init(hc);
  51         (*hc)->update(hc, tmp, blen);
  52         (*hc)->state(hc, ks);
  53 }
  54
  55 /* see bearssl.h */
  56 void
  57 br_hmac_key_init(br_hmac_key_context *kc,
  58         const br_hash_class *dig, const void *key, size_t key_len)
  59 {
  60         br_hash_compat_context hc;
  61         unsigned char kbuf[64];
  62
  63         kc->dig_vtable = dig;
  64         hc.vtable = dig;
  65         if (key_len > block_size(dig)) {
  66                 dig->init(&hc.vtable);
  67                 dig->update(&hc.vtable, key, key_len);
  68                 dig->out(&hc.vtable, kbuf);
  69                 key = kbuf;
  70                 key_len = br_digest_size(dig);
  71         }
  72         process_key(&hc.vtable, kc->ksi, key, key_len, 0x36);
  73         process_key(&hc.vtable, kc->kso, key, key_len, 0x5C);
  74 }
  75
  76 /* see bearssl.h */
  77 void
  78 br_hmac_init(br_hmac_context *ctx,
  79         const br_hmac_key_context *kc, size_t out_len)
  80 {
  81         const br_hash_class *dig;
  82         size_t blen, hlen;
  83
  84         dig = kc->dig_vtable;
  85         blen = block_size(dig);
  86         dig->init(&ctx->dig.vtable);
  87         dig->set_state(&ctx->dig.vtable, kc->ksi, (uint64_t)blen);
  88         memcpy(ctx->kso, kc->kso, sizeof kc->kso);
  89         hlen = br_digest_size(dig);
  90         if (out_len > 0 && out_len < hlen) {
  91                 hlen = out_len;
  92         }
  93         ctx->out_len = hlen;
  94 }
  95
  96 /* see bearssl.h */
  97 void
  98 br_hmac_update(br_hmac_context *ctx, const void *data, size_t len)
  99 {
 100         ctx->dig.vtable->update(&ctx->dig.vtable, data, len);
 101 }
 102
 103 /* see bearssl.h */
 104 size_t
 105 br_hmac_out(const br_hmac_context *ctx, void *out)
 106 {
 107         const br_hash_class *dig;
 108         br_hash_compat_context hc;
 109         unsigned char tmp[64];
 110         size_t blen, hlen;
 111
 112         dig = ctx->dig.vtable;
 113         dig->out(&ctx->dig.vtable, tmp);
 114         blen = block_size(dig);
 115         dig->init(&hc.vtable);
 116         dig->set_state(&hc.vtable, ctx->kso, (uint64_t)blen);
 117         hlen = br_digest_size(dig);
 118         dig->update(&hc.vtable, tmp, hlen);
 119         dig->out(&hc.vtable, tmp);
 120         memcpy(out, tmp, ctx->out_len);
 121         return ctx->out_len;
 122 }