source/lib/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
  27 /***********************************************************************
  28  the rfc 2104 version of hmac_md5 initialisation.
  29 ***********************************************************************/
  30
  31 void hmac_md5_init_rfc2104(const unsigned char *key, int key_len, HMACMD5Context *ctx)
  32 {
  33         int i;
  34         unsigned char tk[16];
  35
  36         /* if key is longer than 64 bytes reset it to key=MD5(key) */
  37         if (key_len > 64) {
  38                 struct MD5Context tctx;
  39
  40                 MD5Init(&tctx);
  41                 MD5Update(&tctx, key, key_len);
  42                 MD5Final(tk, &tctx);
  43
  44                 key = tk;
  45                 key_len = 16;
  46         }
  47
  48         /* start out by storing key in pads */
  49         ZERO_STRUCT(ctx->k_ipad);
  50         ZERO_STRUCT(ctx->k_opad);
  51         memcpy( ctx->k_ipad, key, key_len);
  52         memcpy( ctx->k_opad, key, key_len);
  53
  54         /* XOR key with ipad and opad values */
  55         for (i=0; i<64; i++) {
  56                 ctx->k_ipad[i] ^= 0x36;
  57                 ctx->k_opad[i] ^= 0x5c;
  58         }
  59
  60         MD5Init(&ctx->ctx);
  61         MD5Update(&ctx->ctx, ctx->k_ipad, 64);
  62 }
  63
  64 /***********************************************************************
  65  the microsoft version of hmac_md5 initialisation.
  66 ***********************************************************************/
  67
  68 void hmac_md5_init_limK_to_64(const unsigned char* key, int key_len,
  69                         HMACMD5Context *ctx)
  70 {
  71         int i;
  72
  73         /* if key is longer than 64 bytes truncate it */
  74         if (key_len > 64) {
  75                 key_len = 64;
  76         }
  77
  78         /* start out by storing key in pads */
  79         ZERO_STRUCT(ctx->k_ipad);
  80         ZERO_STRUCT(ctx->k_opad);
  81         memcpy( ctx->k_ipad, key, key_len);
  82         memcpy( ctx->k_opad, key, key_len);
  83
  84         /* XOR key with ipad and opad values */
  85         for (i=0; i<64; i++) {
  86                 ctx->k_ipad[i] ^= 0x36;
  87                 ctx->k_opad[i] ^= 0x5c;
  88         }
  89
  90         MD5Init(&ctx->ctx);
  91         MD5Update(&ctx->ctx, ctx->k_ipad, 64);
  92 }
  93
  94 /***********************************************************************
  95  update hmac_md5 "inner" buffer
  96 ***********************************************************************/
  97
  98 void hmac_md5_update(const unsigned char *text, int text_len, HMACMD5Context *ctx)
  99 {
 100         MD5Update(&ctx->ctx, text, text_len); /* then text of datagram */
 101 }
 102
 103 /***********************************************************************
 104  finish off hmac_md5 "inner" buffer and generate outer one.
 105 ***********************************************************************/
 106 void hmac_md5_final(unsigned char *digest, HMACMD5Context *ctx)
 107
 108 {
 109         struct MD5Context ctx_o;
 110
 111         MD5Final(digest, &ctx->ctx);
 112
 113         MD5Init(&ctx_o);
 114         MD5Update(&ctx_o, ctx->k_opad, 64);
 115         MD5Update(&ctx_o, digest, 16);
 116         MD5Final(digest, &ctx_o);
 117 }
 118
 119 /***********************************************************
 120  single function to calculate an HMAC MD5 digest from data.
 121  use the microsoft hmacmd5 init method because the key is 16 bytes.
 122 ************************************************************/
 123
 124 void hmac_md5( unsigned char key[16], const unsigned char *data, int data_len,
 125                unsigned char *digest)
 126 {
 127         HMACMD5Context ctx;
 128         hmac_md5_init_limK_to_64(key, 16, &ctx);
 129         if (data_len != 0)
 130         {
 131                 hmac_md5_update(data, data_len, &ctx);
 132         }
 133         hmac_md5_final(digest, &ctx);
 134 }
 135