contrib/dhcp-3.0/dst/hmac_link.c

   1 #ifdef HMAC_MD5
   2 #ifndef LINT
   3 static const char rcsid[] = "$Header: /proj/cvs/prod/DHCP/dst/hmac_link.c,v 1.1 2001/02/22 07:22:08 mellon Exp $";
   4 #endif
   5 /*
   6  * Portions Copyright (c) 1995-1998 by Trusted Information Systems, Inc.
   7  *
   8  * Permission to use, copy modify, and distribute this software for any
   9  * purpose with or without fee is hereby granted, provided that the above
  10  * copyright notice and this permission notice appear in all copies.
  11  *
  12  * THE SOFTWARE IS PROVIDED "AS IS" AND TRUSTED INFORMATION SYSTEMS
  13  * DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL
  14  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL
  15  * TRUSTED INFORMATION SYSTEMS BE LIABLE FOR ANY SPECIAL, DIRECT,
  16  * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING
  17  * FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
  18  * NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
  19  * WITH THE USE OR PERFORMANCE OF THE SOFTWARE.
  20  */
  21
  22 /*
  23  * This file contains an implementation of the HMAC-MD5 algorithm.
  24  */
  25
  26 #include <stdio.h>
  27 #include <unistd.h>
  28 #include <stdlib.h>
  29 #include <string.h>
  30 #include <memory.h>
  31 #include <sys/param.h>
  32 #include <sys/time.h>
  33 #include <netinet/in.h>
  34 #include <sys/socket.h>
  35
  36 #include "minires/minires.h"
  37 #include "arpa/nameser.h"
  38
  39 #include "dst_internal.h"
  40
  41 #ifdef USE_MD5
  42 # include "md5.h"
  43 # ifndef _MD5_H_
  44 #  define _MD5_H_ 1     /* make sure we do not include rsaref md5.h file */
  45 # endif
  46 #endif
  47
  48 #define HMAC_LEN        64
  49 #define HMAC_IPAD       0x36
  50 #define HMAC_OPAD       0x5c
  51 #define MD5_LEN         16
  52
  53
  54 typedef struct hmackey {
  55         u_char hk_ipad[64], hk_opad[64];
  56 } HMAC_Key;
  57
  58
  59 /**************************************************************************
  60  * dst_hmac_md5_sign
  61  *     Call HMAC signing functions to sign a block of data.
  62  *     There are three steps to signing, INIT (initialize structures),
  63  *     UPDATE (hash (more) data), FINAL (generate a signature).  This
  64  *     routine performs one or more of these steps.
  65  * Parameters
  66  *     mode     SIG_MODE_INIT, SIG_MODE_UPDATE and/or SIG_MODE_FINAL.
  67  *     priv_key    key to use for signing.
  68  *     context   the context to be used in this digest
  69  *     data     data to be signed.
  70  *     len       length in bytes of data.
  71  *     signature   location to store signature.
  72  *     sig_len     size of the signature location
  73  * returns
  74  *      N  Success on SIG_MODE_FINAL = returns signature length in bytes
  75  *      0  Success on SIG_MODE_INIT  and UPDATE
  76  *       <0  Failure
  77  */
  78
  79 static int
  80 dst_hmac_md5_sign(const int mode, DST_KEY *d_key, void **context,
  81                   const u_char *data, const unsigned len,
  82                   u_char *signature, const unsigned sig_len)
  83 {
  84         HMAC_Key *key;
  85         int sign_len = 0;
  86         MD5_CTX *ctx = NULL;
  87
  88         if (mode & SIG_MODE_INIT)
  89                 ctx = (MD5_CTX *) malloc(sizeof(*ctx));
  90         else if (context)
  91                 ctx = (MD5_CTX *) *context;
  92         if (ctx == NULL)
  93                 return (-1);
  94
  95         if (d_key == NULL || d_key->dk_KEY_struct == NULL)
  96                 return (-1);
  97         key = (HMAC_Key *) d_key->dk_KEY_struct;
  98
  99         if (mode & SIG_MODE_INIT) {
 100                 MD5Init(ctx);
 101                 MD5Update(ctx, key->hk_ipad, HMAC_LEN);
 102         }
 103
 104         if ((mode & SIG_MODE_UPDATE) && (data && len > 0))
 105                 MD5Update(ctx, (const unsigned char *)data, len);
 106
 107         if (mode & SIG_MODE_FINAL) {
 108                 if (signature == NULL || sig_len < MD5_LEN)
 109                         return (SIGN_FINAL_FAILURE);
 110                 MD5Final(signature, ctx);
 111
 112                 /* perform outer MD5 */
 113                 MD5Init(ctx);
 114                 MD5Update(ctx, key->hk_opad, HMAC_LEN);
 115                 MD5Update(ctx, signature, MD5_LEN);
 116                 MD5Final(signature, ctx);
 117                 sign_len = MD5_LEN;
 118                 SAFE_FREE(ctx);
 119         }
 120         else {
 121                 if (context == NULL)
 122                         return (-1);
 123                 *context = (void *) ctx;
 124         }
 125         return (sign_len);
 126 }
 127
 128
 129 /**************************************************************************
 130  * dst_hmac_md5_verify()
 131  *     Calls HMAC verification routines.  There are three steps to
 132  *     verification, INIT (initialize structures), UPDATE (hash (more) data),
 133  *     FINAL (generate a signature).  This routine performs one or more of
 134  *     these steps.
 135  * Parameters
 136  *     mode     SIG_MODE_INIT, SIG_MODE_UPDATE and/or SIG_MODE_FINAL.
 137  *     dkey     key to use for verify.
 138  *     data     data signed.
 139  *     len       length in bytes of data.
 140  *     signature   signature.
 141  *     sig_len     length in bytes of signature.
 142  * returns
 143  *     0  Success
 144  *    <0  Failure
 145  */
 146
 147 static int
 148 dst_hmac_md5_verify(const int mode, DST_KEY *d_key, void **context,
 149                 const u_char *data, const unsigned len,
 150                 const u_char *signature, const unsigned sig_len)
 151 {
 152         HMAC_Key *key;
 153         MD5_CTX *ctx = NULL;
 154
 155         if (mode & SIG_MODE_INIT)
 156                 ctx = (MD5_CTX *) malloc(sizeof(*ctx));
 157         else if (context)
 158                 ctx = (MD5_CTX *) *context;
 159         if (ctx == NULL)
 160                 return (-1);
 161
 162         if (d_key == NULL || d_key->dk_KEY_struct == NULL)
 163                 return (-1);
 164
 165         key = (HMAC_Key *) d_key->dk_KEY_struct;
 166         if (mode & SIG_MODE_INIT) {
 167                 MD5Init(ctx);
 168                 MD5Update(ctx, key->hk_ipad, HMAC_LEN);
 169         }
 170         if ((mode & SIG_MODE_UPDATE) && (data && len > 0))
 171                 MD5Update(ctx, (const unsigned char *)data, len);
 172
 173         if (mode & SIG_MODE_FINAL) {
 174                 u_char digest[MD5_LEN];
 175                 if (signature == NULL || key == NULL || sig_len != MD5_LEN)
 176                         return (VERIFY_FINAL_FAILURE);
 177                 MD5Final(digest, ctx);
 178
 179                 /* perform outer MD5 */
 180                 MD5Init(ctx);
 181                 MD5Update(ctx, key->hk_opad, HMAC_LEN);
 182                 MD5Update(ctx, digest, MD5_LEN);
 183                 MD5Final(digest, ctx);
 184
 185                 SAFE_FREE(ctx);
 186                 if (memcmp(digest, signature, MD5_LEN) != 0)
 187                         return (VERIFY_FINAL_FAILURE);
 188         }
 189         else {
 190                 if (context == NULL)
 191                         return (-1);
 192                 *context = (void *) ctx;
 193         }
 194         return (0);
 195 }
 196
 197
 198 /**************************************************************************
 199  * dst_buffer_to_hmac_md5
 200  *     Converts key from raw data to an HMAC Key
 201  *     This function gets in a pointer to the data
 202  * Parameters
 203  *     hkey     the HMAC key to be filled in
 204  *     key      the key in raw format
 205  *     keylen   the length of the key
 206  * Return
 207  *      0       Success
 208  *      <0      Failure
 209  */
 210 static int
 211 dst_buffer_to_hmac_md5(DST_KEY *dkey, const u_char *key, const unsigned keylen)
 212 {
 213         int i;
 214         HMAC_Key *hkey = NULL;
 215         MD5_CTX ctx;
 216         unsigned local_keylen = keylen;
 217
 218         if (dkey == NULL || key == NULL || keylen < 0)
 219                 return (-1);
 220
 221         if ((hkey = (HMAC_Key *) malloc(sizeof(HMAC_Key))) == NULL)
 222                   return (-2);
 223
 224         memset(hkey->hk_ipad, 0, sizeof(hkey->hk_ipad));
 225         memset(hkey->hk_opad, 0, sizeof(hkey->hk_opad));
 226
 227         /* if key is longer than HMAC_LEN bytes reset it to key=MD5(key) */
 228         if (keylen > HMAC_LEN) {
 229                 u_char tk[MD5_LEN];
 230                 MD5Init(&ctx);
 231                 MD5Update(&ctx, (const unsigned char *)key, keylen);
 232                 MD5Final(tk, &ctx);
 233                 memset((void *) &ctx, 0, sizeof(ctx));
 234                 key = tk;
 235                 local_keylen = MD5_LEN;
 236         }
 237         /* start out by storing key in pads */
 238         memcpy(hkey->hk_ipad, key, local_keylen);
 239         memcpy(hkey->hk_opad, key, local_keylen);
 240
 241         /* XOR key with hk_ipad and opad values */
 242         for (i = 0; i < HMAC_LEN; i++) {
 243                 hkey->hk_ipad[i] ^= HMAC_IPAD;
 244                 hkey->hk_opad[i] ^= HMAC_OPAD;
 245         }
 246         dkey->dk_key_size = local_keylen;
 247         dkey->dk_KEY_struct = (void *) hkey;
 248         return (1);
 249 }
 250
 251
 252 /**************************************************************************
 253  *  dst_hmac_md5_key_to_file_format
 254  *      Encodes an HMAC Key into the portable file format.
 255  *  Parameters
 256  *      hkey      HMAC KEY structure
 257  *      buff      output buffer
 258  *      buff_len  size of output buffer
 259  *  Return
 260  *      0  Failure - null input hkey
 261  *     -1  Failure - not enough space in output area
 262  *      N  Success - Length of data returned in buff
 263  */
 264
 265 static int
 266 dst_hmac_md5_key_to_file_format(const DST_KEY *dkey, char *buff,
 267                             const unsigned buff_len)
 268 {
 269         char *bp;
 270         int i;
 271         unsigned len, b_len, key_len;
 272         u_char key[HMAC_LEN];
 273         HMAC_Key *hkey;
 274
 275         if (dkey == NULL || dkey->dk_KEY_struct == NULL)
 276                 return (0);
 277         if (buff == NULL || buff_len <= (int) strlen(key_file_fmt_str))
 278                 return (-1);    /* no OR not enough space in output area */
 279
 280         hkey = (HMAC_Key *) dkey->dk_KEY_struct;
 281         memset(buff, 0, buff_len);      /* just in case */
 282         /* write file header */
 283         sprintf(buff, key_file_fmt_str, KEY_FILE_FORMAT, KEY_HMAC_MD5, "HMAC");
 284
 285         bp = (char *) strchr(buff, '\0');
 286         b_len = buff_len - (bp - buff);
 287
 288         memset(key, 0, HMAC_LEN);
 289         for (i = 0; i < HMAC_LEN; i++)
 290                 key[i] = hkey->hk_ipad[i] ^ HMAC_IPAD;
 291         for (i = HMAC_LEN - 1; i >= 0; i--)
 292                 if (key[i] != 0)
 293                         break;
 294         key_len = i + 1;
 295
 296         strcat(bp, "Key: ");
 297         bp += strlen("Key: ");
 298         b_len = buff_len - (bp - buff);
 299
 300         len = b64_ntop(key, key_len, bp, b_len);
 301         if (len < 0)
 302                 return (-1);
 303         bp += len;
 304         *(bp++) = '\n';
 305         *bp = '\0';
 306         b_len = buff_len - (bp - buff);
 307
 308         return (buff_len - b_len);
 309 }
 310
 311
 312 /**************************************************************************
 313  * dst_hmac_md5_key_from_file_format
 314  *     Converts contents of a key file into an HMAC key.
 315  * Parameters
 316  *     hkey    structure to put key into
 317  *     buff       buffer containing the encoded key
 318  *     buff_len   the length of the buffer
 319  * Return
 320  *     n >= 0 Foot print of the key converted
 321  *     n <  0 Error in conversion
 322  */
 323
 324 static int
 325 dst_hmac_md5_key_from_file_format(DST_KEY *dkey, const char *buff,
 326                                   const unsigned buff_len)
 327 {
 328         const char *p = buff, *eol;
 329         u_char key[HMAC_LEN+1]; /* b64_pton needs more than 64 bytes do decode
 330                                                          * it should probably be fixed rather than doing
 331                                                          * this
 332                                                          */
 333         u_char *tmp;
 334         unsigned key_len, len;
 335
 336         if (dkey == NULL)
 337                 return (-2);
 338         if (buff == NULL)
 339                 return (-1);
 340
 341         memset(key, 0, sizeof(key));
 342
 343         if (!dst_s_verify_str(&p, "Key: "))
 344                 return (-3);
 345
 346         eol = strchr(p, '\n');
 347         if (eol == NULL)
 348                 return (-4);
 349         len = eol - p;
 350         tmp = malloc(len + 2);
 351         memcpy(tmp, p, len);
 352         *(tmp + len) = 0x0;
 353         key_len = b64_pton((char *)tmp, key, HMAC_LEN+1);       /* see above */
 354         SAFE_FREE2(tmp, len + 2);
 355
 356         if (dst_buffer_to_hmac_md5(dkey, key, key_len) < 0) {
 357                 return (-6);
 358         }
 359         return (0);
 360 }
 361
 362 /*
 363  * dst_hmac_md5_to_dns_key()
 364  *         function to extract hmac key from DST_KEY structure
 365  * intput:
 366  *      in_key:  HMAC-MD5 key
 367  * output:
 368  *      out_str: buffer to write ot
 369  *      out_len: size of output buffer
 370  * returns:
 371  *      number of bytes written to output buffer
 372  */
 373 static int
 374 dst_hmac_md5_to_dns_key(const DST_KEY *in_key, u_char *out_str,
 375                         const unsigned out_len)
 376 {
 377
 378         HMAC_Key *hkey;
 379         int i;
 380
 381         if (in_key == NULL || in_key->dk_KEY_struct == NULL ||
 382             out_len <= in_key->dk_key_size || out_str == NULL)
 383                 return (-1);
 384
 385         hkey = (HMAC_Key *) in_key->dk_KEY_struct;
 386         for (i = 0; i < in_key->dk_key_size; i++)
 387                 out_str[i] = hkey->hk_ipad[i] ^ HMAC_IPAD;
 388         return (i);
 389 }
 390
 391 /**************************************************************************
 392  *  dst_hmac_md5_compare_keys
 393  *      Compare two keys for equality.
 394  *  Return
 395  *      0         The keys are equal
 396  *      NON-ZERO   The keys are not equal
 397  */
 398
 399 static int
 400 dst_hmac_md5_compare_keys(const DST_KEY *key1, const DST_KEY *key2)
 401 {
 402         HMAC_Key *hkey1 = (HMAC_Key *) key1->dk_KEY_struct;
 403         HMAC_Key *hkey2 = (HMAC_Key *) key2->dk_KEY_struct;
 404         return memcmp(hkey1->hk_ipad, hkey2->hk_ipad, HMAC_LEN);
 405 }
 406
 407 /**************************************************************************
 408  * dst_hmac_md5_free_key_structure
 409  *     Frees all (none) dynamically allocated structures in hkey
 410  */
 411
 412 static void *
 413 dst_hmac_md5_free_key_structure(void *key)
 414 {
 415         HMAC_Key *hkey = key;
 416         SAFE_FREE(hkey);
 417         return (NULL);
 418 }
 419
 420
 421 /***************************************************************************
 422  * dst_hmac_md5_generate_key
 423  *     Creates a HMAC key of size size with a maximum size of 63 bytes
 424  *     generating a HMAC key larger than 63 bytes makes no sense as that key
 425  *     is digested before use.
 426  */
 427
 428 static int
 429 dst_hmac_md5_generate_key(DST_KEY *key, const int nothing)
 430 {
 431         u_char *buff;
 432         int n;
 433         unsigned size, len;
 434
 435         if (key == NULL || key->dk_alg != KEY_HMAC_MD5)
 436                 return (0);
 437         size = (key->dk_key_size + 7) / 8; /* convert to bytes */
 438         if (size <= 0)
 439                 return(0);
 440
 441         len = size > 64 ? 64 : size;
 442         buff = malloc(len+8);
 443
 444         n = dst_random(DST_RAND_SEMI, len, buff);
 445         n += dst_random(DST_RAND_KEY, len, buff);
 446         if (n <= len) { /* failed getting anything */
 447                 SAFE_FREE2(buff, len);
 448                 return (-1);
 449         }
 450         n = dst_buffer_to_hmac_md5(key, buff, len);
 451         SAFE_FREE2(buff, len);
 452         if (n <= 0)
 453                 return (n);
 454         return (1);
 455 }
 456
 457 /*
 458  * dst_hmac_md5_init()  Function to answer set up function pointers for HMAC
 459  *         related functions
 460  */
 461 int
 462 dst_hmac_md5_init()
 463 {
 464         if (dst_t_func[KEY_HMAC_MD5] != NULL)
 465                 return (1);
 466         dst_t_func[KEY_HMAC_MD5] = malloc(sizeof(struct dst_func));
 467         if (dst_t_func[KEY_HMAC_MD5] == NULL)
 468                 return (0);
 469         memset(dst_t_func[KEY_HMAC_MD5], 0, sizeof(struct dst_func));
 470         dst_t_func[KEY_HMAC_MD5]->sign = dst_hmac_md5_sign;
 471         dst_t_func[KEY_HMAC_MD5]->verify = dst_hmac_md5_verify;
 472         dst_t_func[KEY_HMAC_MD5]->compare = dst_hmac_md5_compare_keys;
 473         dst_t_func[KEY_HMAC_MD5]->generate = dst_hmac_md5_generate_key;
 474         dst_t_func[KEY_HMAC_MD5]->destroy = dst_hmac_md5_free_key_structure;
 475         dst_t_func[KEY_HMAC_MD5]->to_dns_key = dst_hmac_md5_to_dns_key;
 476         dst_t_func[KEY_HMAC_MD5]->from_dns_key = dst_buffer_to_hmac_md5;
 477         dst_t_func[KEY_HMAC_MD5]->to_file_fmt = dst_hmac_md5_key_to_file_format;
 478         dst_t_func[KEY_HMAC_MD5]->from_file_fmt = dst_hmac_md5_key_from_file_format;
 479         return (1);
 480 }
 481
 482 #else
 483 int
 484 dst_hmac_md5_init(){
 485         return (0);
 486 }
 487 #endif
 488
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