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comparison hmac_file.c @ 3:7faae8f46238 libtomcrypt-orig

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Branch renaming
author Matt Johnston <matt@ucc.asn.au>
date Mon, 31 May 2004 18:25:41 +0000
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children 5d99163f7e32
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-1:000000000000 3:7faae8f46238
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, [email protected], http://libtomcrypt.org
10 */
11 /* Submited by Dobes Vandermeer ([email protected]) */
12
13 #include "mycrypt.h"
14
15 /*
16 (1) append zeros to the end of K to create a B byte string
17 (e.g., if K is of length 20 bytes and B=64, then K will be
18 appended with 44 zero bytes 0x00)
19 (2) XOR (bitwise exclusive-OR) the B byte string computed in step
20 (1) with ipad (ipad = the byte 0x36 repeated B times)
21 (3) append the stream of data 'text' to the B byte string resulting
22 from step (2)
23 (4) apply H to the stream generated in step (3)
24 (5) XOR (bitwise exclusive-OR) the B byte string computed in
25 step (1) with opad (opad = the byte 0x5C repeated B times.)
26 (6) append the H result from step (4) to the B byte string
27 resulting from step (5)
28 (7) apply H to the stream generated in step (6) and output
29 the result
30 */
31
32 #ifdef HMAC
33
34 #define HMAC_BLOCKSIZE hash_descriptor[hash].blocksize
35
36 /* hmac_file added by Tom St Denis */
37 int hmac_file(int hash, const char *fname,
38 const unsigned char *key, unsigned long keylen,
39 unsigned char *dst, unsigned long *dstlen)
40 {
41 #ifdef NO_FILE
42 return CRYPT_NOP;
43 #else
44 hmac_state hmac;
45 FILE *in;
46 unsigned char buf[512];
47 size_t x;
48 int err;
49
50 _ARGCHK(fname != NULL);
51 _ARGCHK(key != NULL);
52 _ARGCHK(dst != NULL);
53 _ARGCHK(dstlen != NULL);
54
55 if((err = hash_is_valid(hash)) != CRYPT_OK) {
56 return err;
57 }
58
59 if ((err = hmac_init(&hmac, hash, key, keylen)) != CRYPT_OK) {
60 return err;
61 }
62
63 in = fopen(fname, "rb");
64 if (in == NULL) {
65 return CRYPT_FILE_NOTFOUND;
66 }
67
68 /* process the file contents */
69 do {
70 x = fread(buf, 1, sizeof(buf), in);
71 if ((err = hmac_process(&hmac, buf, (unsigned long)x)) != CRYPT_OK) {
72 /* we don't trap this error since we're already returning an error! */
73 fclose(in);
74 return err;
75 }
76 } while (x == sizeof(buf));
77
78 if (fclose(in) != 0) {
79 return CRYPT_ERROR;
80 }
81
82 /* get final hmac */
83 if ((err = hmac_done(&hmac, dst, dstlen)) != CRYPT_OK) {
84 return err;
85 }
86
87 #ifdef CLEAN_STACK
88 /* clear memory */
89 zeromem(buf, sizeof(buf));
90 #endif
91 return CRYPT_OK;
92 #endif
93 }
94
95 #endif
96