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comparison src/pk/dsa/dsa_encrypt_key.c @ 380:d5faf4814ddb libtomcrypt-orig libtomcrypt-1.16

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Update to LibTomCrypt 1.16
author Matt Johnston <matt@ucc.asn.au>
date Thu, 11 Jan 2007 02:22:00 +0000
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280:59400faa4b44 380:d5faf4814ddb
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.com
10 */
11 #include "tomcrypt.h"
12
13 /**
14 @file dsa_encrypt_key.c
15 DSA Crypto, Tom St Denis
16 */
17
18 #ifdef MDSA
19
20 /**
21 Encrypt a symmetric key with DSA
22 @param in The symmetric key you want to encrypt
23 @param inlen The length of the key to encrypt (octets)
24 @param out [out] The destination for the ciphertext
25 @param outlen [in/out] The max size and resulting size of the ciphertext
26 @param prng An active PRNG state
27 @param wprng The index of the PRNG you wish to use
28 @param hash The index of the hash you want to use
29 @param key The DSA key you want to encrypt to
30 @return CRYPT_OK if successful
31 */
32 int dsa_encrypt_key(const unsigned char *in, unsigned long inlen,
33 unsigned char *out, unsigned long *outlen,
34 prng_state *prng, int wprng, int hash,
35 dsa_key *key)
36 {
37 unsigned char *expt, *skey;
38 void *g_pub, *g_priv;
39 unsigned long x, y;
40 int err;
41
42 LTC_ARGCHK(in != NULL);
43 LTC_ARGCHK(out != NULL);
44 LTC_ARGCHK(outlen != NULL);
45 LTC_ARGCHK(key != NULL);
46
47 /* check that wprng/cipher/hash are not invalid */
48 if ((err = prng_is_valid(wprng)) != CRYPT_OK) {
49 return err;
50 }
51
52 if ((err = hash_is_valid(hash)) != CRYPT_OK) {
53 return err;
54 }
55
56 if (inlen > hash_descriptor[hash].hashsize) {
57 return CRYPT_INVALID_HASH;
58 }
59
60 /* make a random key and export the public copy */
61 if ((err = mp_init_multi(&g_pub, &g_priv, NULL)) != CRYPT_OK) {
62 return err;
63 }
64
65 expt = XMALLOC(mp_unsigned_bin_size(key->p) + 1);
66 skey = XMALLOC(MAXBLOCKSIZE);
67 if (expt == NULL || skey == NULL) {
68 if (expt != NULL) {
69 XFREE(expt);
70 }
71 if (skey != NULL) {
72 XFREE(skey);
73 }
74 mp_clear_multi(g_pub, g_priv, NULL);
75 return CRYPT_MEM;
76 }
77
78 /* make a random x, g^x pair */
79 x = mp_unsigned_bin_size(key->q);
80 if (prng_descriptor[wprng].read(expt, x, prng) != x) {
81 err = CRYPT_ERROR_READPRNG;
82 goto LBL_ERR;
83 }
84
85 /* load x */
86 if ((err = mp_read_unsigned_bin(g_priv, expt, x)) != CRYPT_OK) {
87 goto LBL_ERR;
88 }
89
90 /* compute y */
91 if ((err = mp_exptmod(key->g, g_priv, key->p, g_pub)) != CRYPT_OK) {
92 goto LBL_ERR;
93 }
94
95 /* make random key */
96 x = mp_unsigned_bin_size(key->p) + 1;
97 if ((err = dsa_shared_secret(g_priv, key->y, key, expt, &x)) != CRYPT_OK) {
98 goto LBL_ERR;
99 }
100
101 y = MAXBLOCKSIZE;
102 if ((err = hash_memory(hash, expt, x, skey, &y)) != CRYPT_OK) {
103 goto LBL_ERR;
104 }
105
106 /* Encrypt key */
107 for (x = 0; x < inlen; x++) {
108 skey[x] ^= in[x];
109 }
110
111 err = der_encode_sequence_multi(out, outlen,
112 LTC_ASN1_OBJECT_IDENTIFIER, hash_descriptor[hash].OIDlen, hash_descriptor[hash].OID,
113 LTC_ASN1_INTEGER, 1UL, g_pub,
114 LTC_ASN1_OCTET_STRING, inlen, skey,
115 LTC_ASN1_EOL, 0UL, NULL);
116
117 LBL_ERR:
118 #ifdef LTC_CLEAN_STACK
119 /* clean up */
120 zeromem(expt, mp_unsigned_bin_size(key->p) + 1);
121 zeromem(skey, MAXBLOCKSIZE);
122 #endif
123
124 XFREE(skey);
125 XFREE(expt);
126
127 mp_clear_multi(g_pub, g_priv, NULL);
128 return err;
129 }
130
131 #endif
132 /* $Source: /cvs/libtom/libtomcrypt/src/pk/dsa/dsa_encrypt_key.c,v $ */
133 /* $Revision: 1.7 $ */
134 /* $Date: 2006/12/04 03:18:43 $ */
135