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comparison libtomcrypt/src/pk/ecc/ecc_make_key.c @ 435:337c45621e81

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merge of 'a9b0496634cdd25647b65e585cc3240f3fa699ee' and 'c22be8b8f570b48e9662dac32c7b3e7148a42206'
author Matt Johnston <matt@ucc.asn.au>
date Thu, 22 Feb 2007 14:53:49 +0000
parents 0cbe8f6dbf9e
children f849a5ca2efc
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434:0aaaf68e97dc 435:337c45621e81
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
12 /* Implements ECC over Z/pZ for curve y^2 = x^3 - 3x + b
13 *
14 * All curves taken from NIST recommendation paper of July 1999
15 * Available at http://csrc.nist.gov/cryptval/dss.htm
16 */
17 #include "tomcrypt.h"
18
19 /**
20 @file ecc_make_key.c
21 ECC Crypto, Tom St Denis
22 */
23
24 #ifdef MECC
25
26 /**
27 Make a new ECC key
28 @param prng An active PRNG state
29 @param wprng The index of the PRNG you wish to use
30 @param keysize The keysize for the new key (in octets from 20 to 65 bytes)
31 @param key [out] Destination of the newly created key
32 @return CRYPT_OK if successful, upon error all allocated memory will be freed
33 */
34 int ecc_make_key(prng_state *prng, int wprng, int keysize, ecc_key *key)
35 {
36 int x, err;
37
38 /* find key size */
39 for (x = 0; (keysize > ltc_ecc_sets[x].size) && (ltc_ecc_sets[x].size != 0); x++);
40 keysize = ltc_ecc_sets[x].size;
41
42 if (keysize > ECC_MAXSIZE || ltc_ecc_sets[x].size == 0) {
43 return CRYPT_INVALID_KEYSIZE;
44 }
45 err = ecc_make_key_ex(prng, wprng, key, &ltc_ecc_sets[x]);
46 key->idx = x;
47 return err;
48 }
49
50 int ecc_make_key_ex(prng_state *prng, int wprng, ecc_key *key, const ltc_ecc_set_type *dp)
51 {
52 int err;
53 ecc_point *base;
54 void *prime;
55 unsigned char *buf;
56 int keysize;
57
58 LTC_ARGCHK(key != NULL);
59 LTC_ARGCHK(ltc_mp.name != NULL);
60 LTC_ARGCHK(dp != NULL);
61
62 /* good prng? */
63 if ((err = prng_is_valid(wprng)) != CRYPT_OK) {
64 return err;
65 }
66
67 key->idx = -1;
68 key->dp = dp;
69 keysize = dp->size;
70
71 /* allocate ram */
72 base = NULL;
73 buf = XMALLOC(ECC_MAXSIZE);
74 if (buf == NULL) {
75 return CRYPT_MEM;
76 }
77
78 /* make up random string */
79 if (prng_descriptor[wprng].read(buf, (unsigned long)keysize, prng) != (unsigned long)keysize) {
80 err = CRYPT_ERROR_READPRNG;
81 goto ERR_BUF;
82 }
83
84 /* setup the key variables */
85 if ((err = mp_init_multi(&key->pubkey.x, &key->pubkey.y, &key->pubkey.z, &key->k, &prime, NULL)) != CRYPT_OK) {
86 goto ERR_BUF;
87 }
88 base = ltc_ecc_new_point();
89 if (base == NULL) {
90 err = CRYPT_MEM;
91 goto errkey;
92 }
93
94 /* read in the specs for this key */
95 if ((err = mp_read_radix(prime, (char *)key->dp->prime, 16)) != CRYPT_OK) { goto errkey; }
96 if ((err = mp_read_radix(base->x, (char *)key->dp->Gx, 16)) != CRYPT_OK) { goto errkey; }
97 if ((err = mp_read_radix(base->y, (char *)key->dp->Gy, 16)) != CRYPT_OK) { goto errkey; }
98 if ((err = mp_set(base->z, 1)) != CRYPT_OK) { goto errkey; }
99 if ((err = mp_read_unsigned_bin(key->k, (unsigned char *)buf, keysize)) != CRYPT_OK) { goto errkey; }
100
101 /* make the public key */
102 if ((err = ltc_mp.ecc_ptmul(key->k, base, &key->pubkey, prime, 1)) != CRYPT_OK) { goto errkey; }
103 key->type = PK_PRIVATE;
104
105 /* free up ram */
106 err = CRYPT_OK;
107 goto cleanup;
108 errkey:
109 mp_clear_multi(key->pubkey.x, key->pubkey.y, key->pubkey.z, key->k, NULL);
110 cleanup:
111 ltc_ecc_del_point(base);
112 mp_clear(prime);
113 ERR_BUF:
114 #ifdef LTC_CLEAN_STACK
115 zeromem(buf, ECC_MAXSIZE);
116 #endif
117 XFREE(buf);
118 return err;
119 }
120
121 #endif
122 /* $Source: /cvs/libtom/libtomcrypt/src/pk/ecc/ecc_make_key.c,v $ */
123 /* $Revision: 1.9 $ */
124 /* $Date: 2006/12/04 02:50:11 $ */
125