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      1 /* Copyright (C) 1995-1998 Eric Young (eay (at) cryptsoft.com)
      2  * All rights reserved.
      3  *
      4  * This package is an SSL implementation written
      5  * by Eric Young (eay (at) cryptsoft.com).
      6  * The implementation was written so as to conform with Netscapes SSL.
      7  *
      8  * This library is free for commercial and non-commercial use as long as
      9  * the following conditions are aheared to.  The following conditions
     10  * apply to all code found in this distribution, be it the RC4, RSA,
     11  * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
     12  * included with this distribution is covered by the same copyright terms
     13  * except that the holder is Tim Hudson (tjh (at) cryptsoft.com).
     14  *
     15  * Copyright remains Eric Young's, and as such any Copyright notices in
     16  * the code are not to be removed.
     17  * If this package is used in a product, Eric Young should be given attribution
     18  * as the author of the parts of the library used.
     19  * This can be in the form of a textual message at program startup or
     20  * in documentation (online or textual) provided with the package.
     21  *
     22  * Redistribution and use in source and binary forms, with or without
     23  * modification, are permitted provided that the following conditions
     24  * are met:
     25  * 1. Redistributions of source code must retain the copyright
     26  *    notice, this list of conditions and the following disclaimer.
     27  * 2. Redistributions in binary form must reproduce the above copyright
     28  *    notice, this list of conditions and the following disclaimer in the
     29  *    documentation and/or other materials provided with the distribution.
     30  * 3. All advertising materials mentioning features or use of this software
     31  *    must display the following acknowledgement:
     32  *    "This product includes cryptographic software written by
     33  *     Eric Young (eay (at) cryptsoft.com)"
     34  *    The word 'cryptographic' can be left out if the rouines from the library
     35  *    being used are not cryptographic related :-).
     36  * 4. If you include any Windows specific code (or a derivative thereof) from
     37  *    the apps directory (application code) you must include an acknowledgement:
     38  *    "This product includes software written by Tim Hudson (tjh (at) cryptsoft.com)"
     39  *
     40  * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
     41  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     42  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     43  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
     44  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     45  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     46  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     47  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     48  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     49  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     50  * SUCH DAMAGE.
     51  *
     52  * The licence and distribution terms for any publically available version or
     53  * derivative of this code cannot be changed.  i.e. this code cannot simply be
     54  * copied and put under another distribution licence
     55  * [including the GNU Public Licence.] */
     56 
     57 #include <openssl/hmac.h>
     58 
     59 #include <assert.h>
     60 #include <string.h>
     61 
     62 #include <openssl/mem.h>
     63 
     64 
     65 uint8_t *HMAC(const EVP_MD *evp_md, const void *key, size_t key_len,
     66               const uint8_t *data, size_t data_len, uint8_t *out,
     67               unsigned int *out_len) {
     68   HMAC_CTX ctx;
     69   static uint8_t static_out_buffer[EVP_MAX_MD_SIZE];
     70 
     71   /* OpenSSL has traditionally supported using a static buffer if |out| is
     72    * NULL. We maintain that but don't document it. This behaviour should be
     73    * considered to be deprecated. */
     74   if (out == NULL) {
     75     out = static_out_buffer;
     76   }
     77 
     78   HMAC_CTX_init(&ctx);
     79   if (!HMAC_Init_ex(&ctx, key, key_len, evp_md, NULL) ||
     80       !HMAC_Update(&ctx, data, data_len) ||
     81       !HMAC_Final(&ctx, out, out_len)) {
     82     out = NULL;
     83   }
     84 
     85   HMAC_CTX_cleanup(&ctx);
     86   return out;
     87 }
     88 
     89 void HMAC_CTX_init(HMAC_CTX *ctx) {
     90   ctx->md = NULL;
     91   EVP_MD_CTX_init(&ctx->i_ctx);
     92   EVP_MD_CTX_init(&ctx->o_ctx);
     93   EVP_MD_CTX_init(&ctx->md_ctx);
     94 }
     95 
     96 void HMAC_CTX_cleanup(HMAC_CTX *ctx) {
     97   EVP_MD_CTX_cleanup(&ctx->i_ctx);
     98   EVP_MD_CTX_cleanup(&ctx->o_ctx);
     99   EVP_MD_CTX_cleanup(&ctx->md_ctx);
    100   OPENSSL_cleanse(ctx, sizeof(HMAC_CTX));
    101 }
    102 
    103 int HMAC_Init_ex(HMAC_CTX *ctx, const void *key, size_t key_len,
    104                  const EVP_MD *md, ENGINE *impl) {
    105   if (md == NULL) {
    106     md = ctx->md;
    107   }
    108 
    109   /* If either |key| is non-NULL or |md| has changed, initialize with a new key
    110    * rather than rewinding the previous one.
    111    *
    112    * TODO(davidben,eroman): Passing the previous |md| with a NULL |key| is
    113    * ambiguous between using the empty key and reusing the previous key. There
    114    * exist callers which intend the latter, but the former is an awkward edge
    115    * case. Fix to API to avoid this. */
    116   if (md != ctx->md || key != NULL) {
    117     size_t i;
    118     uint8_t pad[HMAC_MAX_MD_CBLOCK];
    119     uint8_t key_block[HMAC_MAX_MD_CBLOCK];
    120     unsigned key_block_len;
    121 
    122     size_t block_size = EVP_MD_block_size(md);
    123     assert(block_size <= sizeof(key_block));
    124     if (block_size < key_len) {
    125       /* Long keys are hashed. */
    126       if (!EVP_DigestInit_ex(&ctx->md_ctx, md, impl) ||
    127           !EVP_DigestUpdate(&ctx->md_ctx, key, key_len) ||
    128           !EVP_DigestFinal_ex(&ctx->md_ctx, key_block, &key_block_len)) {
    129         return 0;
    130       }
    131     } else {
    132       assert(key_len <= sizeof(key_block));
    133       memcpy(key_block, key, key_len);
    134       key_block_len = (unsigned)key_len;
    135     }
    136     /* Keys are then padded with zeros. */
    137     if (key_block_len != HMAC_MAX_MD_CBLOCK) {
    138       memset(&key_block[key_block_len], 0, sizeof(key_block) - key_block_len);
    139     }
    140 
    141     for (i = 0; i < HMAC_MAX_MD_CBLOCK; i++) {
    142       pad[i] = 0x36 ^ key_block[i];
    143     }
    144     if (!EVP_DigestInit_ex(&ctx->i_ctx, md, impl) ||
    145         !EVP_DigestUpdate(&ctx->i_ctx, pad, EVP_MD_block_size(md))) {
    146       return 0;
    147     }
    148 
    149     for (i = 0; i < HMAC_MAX_MD_CBLOCK; i++) {
    150       pad[i] = 0x5c ^ key_block[i];
    151     }
    152     if (!EVP_DigestInit_ex(&ctx->o_ctx, md, impl) ||
    153         !EVP_DigestUpdate(&ctx->o_ctx, pad, EVP_MD_block_size(md))) {
    154       return 0;
    155     }
    156 
    157     ctx->md = md;
    158   }
    159 
    160   if (!EVP_MD_CTX_copy_ex(&ctx->md_ctx, &ctx->i_ctx)) {
    161     return 0;
    162   }
    163 
    164   return 1;
    165 }
    166 
    167 int HMAC_Update(HMAC_CTX *ctx, const uint8_t *data, size_t data_len) {
    168   return EVP_DigestUpdate(&ctx->md_ctx, data, data_len);
    169 }
    170 
    171 int HMAC_Final(HMAC_CTX *ctx, uint8_t *out, unsigned int *out_len) {
    172   unsigned int i;
    173   uint8_t buf[EVP_MAX_MD_SIZE];
    174 
    175   /* TODO(davidben): The only thing that can officially fail here is
    176    * |EVP_MD_CTX_copy_ex|, but even that should be impossible in this case. */
    177   if (!EVP_DigestFinal_ex(&ctx->md_ctx, buf, &i) ||
    178       !EVP_MD_CTX_copy_ex(&ctx->md_ctx, &ctx->o_ctx) ||
    179       !EVP_DigestUpdate(&ctx->md_ctx, buf, i) ||
    180       !EVP_DigestFinal_ex(&ctx->md_ctx, out, out_len)) {
    181     *out_len = 0;
    182     return 0;
    183   }
    184 
    185   return 1;
    186 }
    187 
    188 size_t HMAC_size(const HMAC_CTX *ctx) {
    189   return EVP_MD_size(ctx->md);
    190 }
    191 
    192 int HMAC_CTX_copy_ex(HMAC_CTX *dest, const HMAC_CTX *src) {
    193   if (!EVP_MD_CTX_copy_ex(&dest->i_ctx, &src->i_ctx) ||
    194       !EVP_MD_CTX_copy_ex(&dest->o_ctx, &src->o_ctx) ||
    195       !EVP_MD_CTX_copy_ex(&dest->md_ctx, &src->md_ctx)) {
    196     return 0;
    197   }
    198 
    199   dest->md = src->md;
    200   return 1;
    201 }
    202 
    203 int HMAC_Init(HMAC_CTX *ctx, const void *key, int key_len, const EVP_MD *md) {
    204   if (key && md) {
    205     HMAC_CTX_init(ctx);
    206   }
    207   return HMAC_Init_ex(ctx, key, key_len, md, NULL);
    208 }
    209 
    210 int HMAC_CTX_copy(HMAC_CTX *dest, const HMAC_CTX *src) {
    211   HMAC_CTX_init(dest);
    212   return HMAC_CTX_copy_ex(dest, src);
    213 }
    214