Mercurial > dropbear

comparison libtomcrypt/src/encauth/eax/eax_done.c @ 285:1b9e69c058d2

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 20dccfc09627970a312d77fb41dc2970b62689c3) to branch 'au.asn.ucc.matt.dropbear' (head fdf4a7a3b97ae5046139915de7e40399cceb2c01)
author Matt Johnston <matt@ucc.asn.au>
date Wed, 08 Mar 2006 13:23:58 +0000
parents
children 0cbe8f6dbf9e
comparison
equal deleted inserted replaced
281:997e6f7dc01e 285:1b9e69c058d2
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
12 /**
13 @file eax_done.c
14 EAX implementation, terminate session, by Tom St Denis
15 */
16 #include "tomcrypt.h"
17
18 #ifdef EAX_MODE
19
20 /**
21 Terminate an EAX session and get the tag.
22 @param eax The EAX state
23 @param tag [out] The destination of the authentication tag
24 @param taglen [in/out] The max length and resulting length of the authentication tag
25 @return CRYPT_OK if successful
26 */
27 int eax_done(eax_state *eax, unsigned char *tag, unsigned long *taglen)
28 {
29 int err;
30 unsigned char *headermac, *ctmac;
31 unsigned long x, len;
32
33 LTC_ARGCHK(eax != NULL);
34 LTC_ARGCHK(tag != NULL);
35 LTC_ARGCHK(taglen != NULL);
36
37 /* allocate ram */
38 headermac = XMALLOC(MAXBLOCKSIZE);
39 ctmac = XMALLOC(MAXBLOCKSIZE);
40
41 if (headermac == NULL || ctmac == NULL) {
42 if (headermac != NULL) {
43 XFREE(headermac);
44 }
45 if (ctmac != NULL) {
46 XFREE(ctmac);
47 }
48 return CRYPT_MEM;
49 }
50
51 /* finish ctomac */
52 len = MAXBLOCKSIZE;
53 if ((err = omac_done(&eax->ctomac, ctmac, &len)) != CRYPT_OK) {
54 goto LBL_ERR;
55 }
56
57 /* finish headeromac */
58
59 /* note we specifically don't reset len so the two lens are minimal */
60
61 if ((err = omac_done(&eax->headeromac, headermac, &len)) != CRYPT_OK) {
62 goto LBL_ERR;
63 }
64
65 /* terminate the CTR chain */
66 if ((err = ctr_done(&eax->ctr)) != CRYPT_OK) {
67 goto LBL_ERR;
68 }
69
70 /* compute N xor H xor C */
71 for (x = 0; x < len && x < *taglen; x++) {
72 tag[x] = eax->N[x] ^ headermac[x] ^ ctmac[x];
73 }
74 *taglen = x;
75
76 err = CRYPT_OK;
77 LBL_ERR:
78 #ifdef LTC_CLEAN_STACK
79 zeromem(ctmac, MAXBLOCKSIZE);
80 zeromem(headermac, MAXBLOCKSIZE);
81 zeromem(eax, sizeof(*eax));
82 #endif
83
84 XFREE(ctmac);
85 XFREE(headermac);
86
87 return err;
88 }
89
90 #endif
91
92 /* $Source: /cvs/libtom/libtomcrypt/src/encauth/eax/eax_done.c,v $ */
93 /* $Revision: 1.4 $ */
94 /* $Date: 2005/05/05 14:35:58 $ */