_ Git - BearSSL/blob - src/hash/multihash.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 /*
  28  * An aggregate context that is large enough for all supported hash
  29  * functions.
  30  */
  31 typedef union {
  32         const br_hash_class *vtable;
  33         br_md5_context md5;
  34         br_sha1_context sha1;
  35         br_sha224_context sha224;
  36         br_sha256_context sha256;
  37         br_sha384_context sha384;
  38         br_sha512_context sha512;
  39 } gen_hash_context;
  40
  41 /*
  42  * Get the offset to the state for a specific hash function within the
  43  * context structure. This shall be called only for the supported hash
  44  * functions,
  45  */
  46 static size_t
  47 get_state_offset(int id)
  48 {
  49         if (id >= 5) {
  50                 /*
  51                  * SHA-384 has id 5, and SHA-512 has id 6. Both use
  52                  * eight 64-bit words for their state.
  53                  */
  54                 return offsetof(br_multihash_context, val_64)
  55                         + ((size_t)(id - 5) * (8 * sizeof(uint64_t)));
  56         } else {
  57                 /*
  58                  * MD5 has id 1, SHA-1 has id 2, SHA-224 has id 3 and
  59                  * SHA-256 has id 4. They use 32-bit words for their
  60                  * states (4 words for MD5, 5 for SHA-1, 8 for SHA-224
  61                  * and 8 for SHA-256).
  62                  */
  63                 unsigned x;
  64
  65                 x = id - 1;
  66                 x = ((x + (x & (x >> 1))) << 2) + (x >> 1);
  67                 return offsetof(br_multihash_context, val_32)
  68                         + x * sizeof(uint32_t);
  69         }
  70 }
  71
  72 /* see bearssl_hash.h */
  73 void
  74 br_multihash_zero(br_multihash_context *ctx)
  75 {
  76         /*
  77          * This is not standard, but yields very short and efficient code,
  78          * and it works "everywhere".
  79          */
  80         memset(ctx, 0, sizeof *ctx);
  81 }
  82
  83 /* see bearssl_hash.h */
  84 void
  85 br_multihash_init(br_multihash_context *ctx)
  86 {
  87         int i;
  88
  89         ctx->count = 0;
  90         for (i = 1; i <= 6; i ++) {
  91                 const br_hash_class *hc;
  92
  93                 hc = ctx->impl[i - 1];
  94                 if (hc != NULL) {
  95                         gen_hash_context g;
  96
  97                         hc->init(&g.vtable);
  98                         hc->state(&g.vtable,
  99                                 (unsigned char *)ctx + get_state_offset(i));
 100                 }
 101         }
 102 }
 103
 104 /* see bearssl_hash.h */
 105 void
 106 br_multihash_update(br_multihash_context *ctx, const void *data, size_t len)
 107 {
 108         const unsigned char *buf;
 109         size_t ptr;
 110
 111         buf = data;
 112         ptr = (size_t)ctx->count & 127;
 113         while (len > 0) {
 114                 size_t clen;
 115
 116                 clen = 128 - ptr;
 117                 if (clen > len) {
 118                         clen = len;
 119                 }
 120                 memcpy(ctx->buf + ptr, buf, clen);
 121                 ptr += clen;
 122                 buf += clen;
 123                 len -= clen;
 124                 ctx->count += (uint64_t)clen;
 125                 if (ptr == 128) {
 126                         int i;
 127
 128                         for (i = 1; i <= 6; i ++) {
 129                                 const br_hash_class *hc;
 130
 131                                 hc = ctx->impl[i - 1];
 132                                 if (hc != NULL) {
 133                                         gen_hash_context g;
 134                                         unsigned char *state;
 135
 136                                         state = (unsigned char *)ctx
 137                                                 + get_state_offset(i);
 138                                         hc->set_state(&g.vtable,
 139                                                 state, ctx->count - 128);
 140                                         hc->update(&g.vtable, ctx->buf, 128);
 141                                         hc->state(&g.vtable, state);
 142                                 }
 143                         }
 144                         ptr = 0;
 145                 }
 146         }
 147 }
 148
 149 /* see bearssl_hash.h */
 150 size_t
 151 br_multihash_out(const br_multihash_context *ctx, int id, void *dst)
 152 {
 153         const br_hash_class *hc;
 154         gen_hash_context g;
 155         const unsigned char *state;
 156
 157         hc = ctx->impl[id - 1];
 158         if (hc == NULL) {
 159                 return 0;
 160         }
 161         state = (const unsigned char *)ctx + get_state_offset(id);
 162         hc->set_state(&g.vtable, state, ctx->count & ~(uint64_t)127);
 163         hc->update(&g.vtable, ctx->buf, ctx->count & (uint64_t)127);
 164         hc->out(&g.vtable, dst);
 165         return (hc->desc >> BR_HASHDESC_OUT_OFF) & BR_HASHDESC_OUT_MASK;
 166 }