Line data    Source code

       1             : /*
       2             :  * Copyright (c) 2015, Secure Endpoints Inc.
       3             :  * All rights reserved.
       4             :  *
       5             :  * Redistribution and use in source and binary forms, with or without
       6             :  * modification, are permitted provided that the following conditions
       7             :  * are met:
       8             :  *
       9             :  * - Redistributions of source code must retain the above copyright
      10             :  *   notice, this list of conditions and the following disclaimer.
      11             :  *
      12             :  * - Redistributions in binary form must reproduce the above copyright
      13             :  *   notice, this list of conditions and the following disclaimer in
      14             :  *   the documentation and/or other materials provided with the
      15             :  *   distribution.
      16             :  *
      17             :  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
      18             :  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
      19             :  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
      20             :  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
      21             :  * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
      22             :  * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
      23             :  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
      24             :  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
      25             :  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
      26             :  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
      27             :  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
      28             :  * OF THE POSSIBILITY OF SUCH DAMAGE.
      29             :  *
      30             :  */
      31             : 
      32             : #include "krb5_locl.h"
      33             : 
      34             : /*
      35             :  * SP800-108 KDF
      36             :  */
      37             : 
      38             : /**
      39             :  * As described in SP800-108 5.1 (for HMAC)
      40             :  *
      41             :  * @param context       Kerberos 5 context
      42             :  * @param kdf_K1        Base key material.
      43             :  * @param kdf_label     A string that identifies the purpose for the derived key.
      44             :  * @param kdf_context   A binary string containing parties, nonce, etc.
      45             :  * @param md            Message digest function to use for PRF.
      46             :  * @param kdf_K0        Derived key data.
      47             :  *
      48             :  * @return Return an error code for an failure or 0 on success.
      49             :  * @ingroup krb5_crypto
      50             :  */
      51             : krb5_error_code
      52           0 : _krb5_SP800_108_HMAC_KDF(krb5_context context,
      53             :                          const krb5_data *kdf_K1,
      54             :                          const krb5_data *kdf_label,
      55             :                          const krb5_data *kdf_context,
      56             :                          const EVP_MD *md,
      57             :                          krb5_data *kdf_K0)
      58             : {
      59           0 :     HMAC_CTX c;
      60           0 :     unsigned char *p = kdf_K0->data;
      61           0 :     size_t i, n, left = kdf_K0->length;
      62           0 :     unsigned char hmac[EVP_MAX_MD_SIZE];
      63           0 :     unsigned int h = EVP_MD_size(md);
      64           0 :     const size_t L = kdf_K0->length;
      65             : 
      66           0 :     heim_assert(md != NULL, "SP800-108 KDF internal error");
      67             : 
      68           0 :     HMAC_CTX_init(&c);
      69             : 
      70           0 :     n = L / h;
      71             : 
      72           0 :     for (i = 0; i <= n; i++) {
      73           0 :         unsigned char tmp[4];
      74           0 :         size_t len;
      75             : 
      76           0 :         if (HMAC_Init_ex(&c, kdf_K1->data, kdf_K1->length, md, NULL) == 0) {
      77           0 :             HMAC_CTX_cleanup(&c);
      78           0 :             return krb5_enomem(context);
      79             :         }
      80             : 
      81           0 :         _krb5_put_int(tmp, i + 1, 4);
      82           0 :         HMAC_Update(&c, tmp, 4);
      83           0 :         HMAC_Update(&c, kdf_label->data, kdf_label->length);
      84           0 :         HMAC_Update(&c, (unsigned char *)"", 1);
      85           0 :         if (kdf_context)
      86           0 :             HMAC_Update(&c, kdf_context->data, kdf_context->length);
      87           0 :         _krb5_put_int(tmp, L * 8, 4);
      88           0 :         HMAC_Update(&c, tmp, 4);
      89             : 
      90           0 :         HMAC_Final(&c, hmac, &h);
      91           0 :         len = h > left ? left : h;
      92           0 :         memcpy(p, hmac, len);
      93           0 :         p += len;
      94           0 :         left -= len;
      95             :     }
      96             : 
      97           0 :     HMAC_CTX_cleanup(&c);
      98             : 
      99           0 :     return 0;
     100             : }