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 2 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, write to the Free Software
  19    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  20 */
  21
  22 /* taken direct from rfc2104 implementation and modified for suitable use
  23  * for ntlmv2.
  24  */
  25
  26 #include "includes.h"
  27
  28 /***********************************************************************
  29  the rfc 2104 version of hmac_md5 initialisation.
  30 ***********************************************************************/
  31 void hmac_md5_init_rfc2104(uchar*  key, int key_len, HMACMD5Context *ctx)
  32 {
  33         int i;
  34
  35         /* if key is longer than 64 bytes reset it to key=MD5(key) */
  36         if (key_len > 64)
  37         {
  38                 uchar tk[16];
  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 void hmac_md5_init_limK_to_64(const uchar* key, int key_len,
  70                         HMACMD5Context *ctx)
  71 {
  72         int i;
  73
  74         /* if key is longer than 64 bytes truncate it */
  75         if (key_len > 64)
  76         {
  77                 key_len = 64;
  78         }
  79
  80         /* start out by storing key in pads */
  81         ZERO_STRUCT(ctx->k_ipad);
  82         ZERO_STRUCT(ctx->k_opad);
  83         memcpy( ctx->k_ipad, key, key_len);
  84         memcpy( ctx->k_opad, key, key_len);
  85
  86         /* XOR key with ipad and opad values */
  87         for (i=0; i<64; i++) {
  88                 ctx->k_ipad[i] ^= 0x36;
  89                 ctx->k_opad[i] ^= 0x5c;
  90         }
  91
  92         MD5Init(&ctx->ctx);
  93         MD5Update(&ctx->ctx, ctx->k_ipad, 64);
  94 }
  95
  96 /***********************************************************************
  97  update hmac_md5 "inner" buffer
  98 ***********************************************************************/
  99 void hmac_md5_update(const uchar* text, int text_len, HMACMD5Context *ctx)
 100 {
 101         MD5Update(&ctx->ctx, text, text_len); /* then text of datagram */
 102 }
 103
 104 /***********************************************************************
 105  finish off hmac_md5 "inner" buffer and generate outer one.
 106 ***********************************************************************/
 107 void hmac_md5_final(uchar *digest, HMACMD5Context *ctx)
 108
 109 {
 110         struct MD5Context ctx_o;
 111
 112         MD5Final(digest, &ctx->ctx);
 113
 114         MD5Init(&ctx_o);
 115         MD5Update(&ctx_o, ctx->k_opad, 64);
 116         MD5Update(&ctx_o, digest, 16);
 117         MD5Final(digest, &ctx_o);
 118 }
 119
 120 /***********************************************************
 121  single function to calculate an HMAC MD5 digest from data.
 122  use the microsoft hmacmd5 init method because the key is 16 bytes.
 123 ************************************************************/
 124 void hmac_md5( uchar key[16], uchar* data, int data_len, uchar* digest)
 125 {
 126         HMACMD5Context ctx;
 127         hmac_md5_init_limK_to_64(key, 16, &ctx);
 128         if (data_len != 0)
 129         {
 130                 hmac_md5_update(data, data_len, &ctx);
 131         }
 132         hmac_md5_final(digest, &ctx);
 133 }
 134