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 (at) gmail.com, 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, <c_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 $ */ 125 126
