lib/crypto/hmacmd5.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    HMAC MD5 code for use in NTLMv2
   4    Copyright (C) Luke Kenneth Casson Leighton 1996-2000
   5    Copyright (C) Andrew Tridgell 1992-2000
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  19 */
  20
  21 /* taken direct from rfc2104 implementation and modified for suitable use
  22  * for ntlmv2.
  23  */
  24
  25 #include "includes.h"
  26 #include "../lib/crypto/hmacmd5.h"
  27
  28 /***********************************************************************
  29  the rfc 2104 version of hmac_md5 initialisation.
  30 ***********************************************************************/
  31 _PUBLIC_ void hmac_md5_init_rfc2104(const uint8_t *key, int key_len, HMACMD5Context *ctx)
  32 {
  33         int i;
  34         uint8_t tk[16];
  35
  36         /* if key is longer than 64 bytes reset it to key=MD5(key) */
  37         if (key_len > 64)
  38         {
  39                 struct MD5Context tctx;
  40
  41                 MD5Init(&tctx);
  42                 MD5Update(&tctx, key, key_len);
  43                 MD5Final(tk, &tctx);
  44
  45                 key = tk;
  46                 key_len = 16;
  47         }
  48
  49         /* start out by storing key in pads */
  50         ZERO_STRUCT(ctx->k_ipad);
  51         ZERO_STRUCT(ctx->k_opad);
  52         memcpy( ctx->k_ipad, key, key_len);
  53         memcpy( ctx->k_opad, key, key_len);
  54
  55         /* XOR key with ipad and opad values */
  56         for (i=0; i<64; i++)
  57         {
  58                 ctx->k_ipad[i] ^= 0x36;
  59                 ctx->k_opad[i] ^= 0x5c;
  60         }
  61
  62         MD5Init(&ctx->ctx);
  63         MD5Update(&ctx->ctx, ctx->k_ipad, 64);
  64 }
  65
  66 /***********************************************************************
  67  the microsoft version of hmac_md5 initialisation.
  68 ***********************************************************************/
  69 _PUBLIC_ void hmac_md5_init_limK_to_64(const uint8_t *key, int key_len,
  70                         HMACMD5Context *ctx)
  71 {
  72         /* if key is longer than 64 bytes truncate it */
  73         if (key_len > 64)
  74         {
  75                 key_len = 64;
  76         }
  77
  78         hmac_md5_init_rfc2104(key, key_len, ctx);
  79 }
  80
  81 /***********************************************************************
  82  update hmac_md5 "inner" buffer
  83 ***********************************************************************/
  84 _PUBLIC_ void hmac_md5_update(const uint8_t *text, int text_len, HMACMD5Context *ctx)
  85 {
  86         MD5Update(&ctx->ctx, text, text_len); /* then text of datagram */
  87 }
  88
  89 /***********************************************************************
  90  finish off hmac_md5 "inner" buffer and generate outer one.
  91 ***********************************************************************/
  92 _PUBLIC_ void hmac_md5_final(uint8_t *digest, HMACMD5Context *ctx)
  93 {
  94         struct MD5Context ctx_o;
  95
  96         MD5Final(digest, &ctx->ctx);
  97
  98         MD5Init(&ctx_o);
  99         MD5Update(&ctx_o, ctx->k_opad, 64);
 100         MD5Update(&ctx_o, digest, 16);
 101         MD5Final(digest, &ctx_o);
 102 }
 103
 104 /***********************************************************
 105  single function to calculate an HMAC MD5 digest from data.
 106  use the microsoft hmacmd5 init method because the key is 16 bytes.
 107 ************************************************************/
 108 _PUBLIC_ void hmac_md5(const uint8_t key[16], const uint8_t *data, int data_len, uint8_t *digest)
 109 {
 110         HMACMD5Context ctx;
 111         hmac_md5_init_limK_to_64(key, 16, &ctx);
 112         if (data_len != 0)
 113         {
 114                 hmac_md5_update(data, data_len, &ctx);
 115         }
 116         hmac_md5_final(digest, &ctx);
 117 }