1/* LibTomCrypt, modular cryptographic library -- Tom St Denis
2 *
3 * LibTomCrypt is a library that provides various cryptographic
4 * algorithms in a highly modular and flexible manner.
5 *
6 * The library is free for all purposes without any express
7 * guarantee it works.
8 *
9 * Tom St Denis, tomstdenis@gmail.com, http://libtomcrypt.com
10 */
11#include "tomcrypt.h"
12
13/**
14  @file hmac_file.c
15  HMAC support, process a file, Tom St Denis/Dobes Vandermeer
16*/
17
18#ifdef LTC_HMAC
19
20/**
21  HMAC a file
22  @param hash     The index of the hash you wish to use
23  @param fname    The name of the file you wish to HMAC
24  @param key      The secret key
25  @param keylen   The length of the secret key
26  @param out      [out] The HMAC authentication tag
27  @param outlen   [in/out]  The max size and resulting size of the authentication tag
28  @return CRYPT_OK if successful, CRYPT_NOP if file support has been disabled
29*/
30int hmac_file(int hash, const char *fname,
31              const unsigned char *key, unsigned long keylen,
32                    unsigned char *out, unsigned long *outlen)
33{
34#ifdef LTC_NO_FILE
35    return CRYPT_NOP;
36#else
37   hmac_state hmac;
38   FILE *in;
39   unsigned char buf[512];
40   size_t x;
41   int err;
42
43   LTC_ARGCHK(fname  != NULL);
44   LTC_ARGCHK(key    != NULL);
45   LTC_ARGCHK(out    != NULL);
46   LTC_ARGCHK(outlen != NULL);
47
48   if((err = hash_is_valid(hash)) != CRYPT_OK) {
49       return err;
50   }
51
52   if ((err = hmac_init(&hmac, hash, key, keylen)) != CRYPT_OK) {
53       return err;
54   }
55
56   in = fopen(fname, "rb");
57   if (in == NULL) {
58      return CRYPT_FILE_NOTFOUND;
59   }
60
61   /* process the file contents */
62   do {
63      x = fread(buf, 1, sizeof(buf), in);
64      if ((err = hmac_process(&hmac, buf, (unsigned long)x)) != CRYPT_OK) {
65         /* we don't trap this error since we're already returning an error! */
66         fclose(in);
67         return err;
68      }
69   } while (x == sizeof(buf));
70
71   if (fclose(in) != 0) {
72      return CRYPT_ERROR;
73   }
74
75   /* get final hmac */
76   if ((err = hmac_done(&hmac, out, outlen)) != CRYPT_OK) {
77      return err;
78   }
79
80#ifdef LTC_CLEAN_STACK
81   /* clear memory */
82   zeromem(buf, sizeof(buf));
83#endif
84   return CRYPT_OK;
85#endif
86}
87
88#endif
89
90
91/* $Source: /cvs/libtom/libtomcrypt/src/mac/hmac/hmac_file.c,v $ */
92/* $Revision: 1.5 $ */
93/* $Date: 2006/11/03 00:39:49 $ */
94