Mercurial > dropbear
view libtomcrypt/src/pk/ecc/ecc_import.c @ 753:d63ef1e211ea
Take transmit and receive keys into use separately
author | Matt Johnston <matt@ucc.asn.au> |
---|---|
date | Thu, 04 Apr 2013 00:18:50 +0800 |
parents | 0cbe8f6dbf9e |
children | ac2158e3e403 |
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/* LibTomCrypt, modular cryptographic library -- Tom St Denis * * LibTomCrypt is a library that provides various cryptographic * algorithms in a highly modular and flexible manner. * * The library is free for all purposes without any express * guarantee it works. * * Tom St Denis, [email protected], http://libtomcrypt.com */ /* Implements ECC over Z/pZ for curve y^2 = x^3 - 3x + b * * All curves taken from NIST recommendation paper of July 1999 * Available at http://csrc.nist.gov/cryptval/dss.htm */ #include "tomcrypt.h" /** @file ecc_import.c ECC Crypto, Tom St Denis */ #ifdef MECC static int is_point(ecc_key *key) { void *prime, *b, *t1, *t2; int err; if ((err = mp_init_multi(&prime, &b, &t1, &t2, NULL)) != CRYPT_OK) { return err; } /* load prime and b */ if ((err = mp_read_radix(prime, key->dp->prime, 16)) != CRYPT_OK) { goto error; } if ((err = mp_read_radix(b, key->dp->B, 16)) != CRYPT_OK) { goto error; } /* compute y^2 */ if ((err = mp_sqr(key->pubkey.y, t1)) != CRYPT_OK) { goto error; } /* compute x^3 */ if ((err = mp_sqr(key->pubkey.x, t2)) != CRYPT_OK) { goto error; } if ((err = mp_mod(t2, prime, t2)) != CRYPT_OK) { goto error; } if ((err = mp_mul(key->pubkey.x, t2, t2)) != CRYPT_OK) { goto error; } /* compute y^2 - x^3 */ if ((err = mp_sub(t1, t2, t1)) != CRYPT_OK) { goto error; } /* compute y^2 - x^3 + 3x */ if ((err = mp_add(t1, key->pubkey.x, t1)) != CRYPT_OK) { goto error; } if ((err = mp_add(t1, key->pubkey.x, t1)) != CRYPT_OK) { goto error; } if ((err = mp_add(t1, key->pubkey.x, t1)) != CRYPT_OK) { goto error; } if ((err = mp_mod(t1, prime, t1)) != CRYPT_OK) { goto error; } while (mp_cmp_d(t1, 0) == LTC_MP_LT) { if ((err = mp_add(t1, prime, t1)) != CRYPT_OK) { goto error; } } while (mp_cmp(t1, prime) != LTC_MP_LT) { if ((err = mp_sub(t1, prime, t1)) != CRYPT_OK) { goto error; } } /* compare to b */ if (mp_cmp(t1, b) != LTC_MP_EQ) { err = CRYPT_INVALID_PACKET; } else { err = CRYPT_OK; } error: mp_clear_multi(prime, b, t1, t2, NULL); return err; } /** Import an ECC key from a binary packet @param in The packet to import @param inlen The length of the packet @param key [out] The destination of the import @return CRYPT_OK if successful, upon error all allocated memory will be freed */ int ecc_import(const unsigned char *in, unsigned long inlen, ecc_key *key) { return ecc_import_ex(in, inlen, key, NULL); } /** Import an ECC key from a binary packet, using user supplied domain params rather than one of the NIST ones @param in The packet to import @param inlen The length of the packet @param key [out] The destination of the import @param dp pointer to user supplied params; must be the same as the params used when exporting @return CRYPT_OK if successful, upon error all allocated memory will be freed */ int ecc_import_ex(const unsigned char *in, unsigned long inlen, ecc_key *key, const ltc_ecc_set_type *dp) { unsigned long key_size; unsigned char flags[1]; int err; LTC_ARGCHK(in != NULL); LTC_ARGCHK(key != NULL); LTC_ARGCHK(ltc_mp.name != NULL); /* init key */ if (mp_init_multi(&key->pubkey.x, &key->pubkey.y, &key->pubkey.z, &key->k, NULL) != CRYPT_OK) { return CRYPT_MEM; } /* find out what type of key it is */ if ((err = der_decode_sequence_multi(in, inlen, LTC_ASN1_BIT_STRING, 1UL, &flags, LTC_ASN1_EOL, 0UL, NULL)) != CRYPT_OK) { goto done; } if (flags[0] == 1) { /* private key */ key->type = PK_PRIVATE; if ((err = der_decode_sequence_multi(in, inlen, LTC_ASN1_BIT_STRING, 1UL, flags, LTC_ASN1_SHORT_INTEGER, 1UL, &key_size, LTC_ASN1_INTEGER, 1UL, key->pubkey.x, LTC_ASN1_INTEGER, 1UL, key->pubkey.y, LTC_ASN1_INTEGER, 1UL, key->k, LTC_ASN1_EOL, 0UL, NULL)) != CRYPT_OK) { goto done; } } else { /* public key */ key->type = PK_PUBLIC; if ((err = der_decode_sequence_multi(in, inlen, LTC_ASN1_BIT_STRING, 1UL, flags, LTC_ASN1_SHORT_INTEGER, 1UL, &key_size, LTC_ASN1_INTEGER, 1UL, key->pubkey.x, LTC_ASN1_INTEGER, 1UL, key->pubkey.y, LTC_ASN1_EOL, 0UL, NULL)) != CRYPT_OK) { goto done; } } if (dp == NULL) { /* find the idx */ for (key->idx = 0; ltc_ecc_sets[key->idx].size && (unsigned long)ltc_ecc_sets[key->idx].size != key_size; ++key->idx); if (ltc_ecc_sets[key->idx].size == 0) { err = CRYPT_INVALID_PACKET; goto done; } key->dp = <c_ecc_sets[key->idx]; } else { key->idx = -1; key->dp = dp; } /* set z */ if ((err = mp_set(key->pubkey.z, 1)) != CRYPT_OK) { goto done; } /* is it a point on the curve? */ if ((err = is_point(key)) != CRYPT_OK) { goto done; } /* we're good */ return CRYPT_OK; done: mp_clear_multi(key->pubkey.x, key->pubkey.y, key->pubkey.z, key->k, NULL); return err; } #endif /* $Source: /cvs/libtom/libtomcrypt/src/pk/ecc/ecc_import.c,v $ */ /* $Revision: 1.11 $ */ /* $Date: 2006/12/04 02:19:48 $ */