diff options
Diffstat (limited to 'libtomcrypt/src/pk/ecc/ecc_import.c')
| -rw-r--r-- | libtomcrypt/src/pk/ecc/ecc_import.c | 172 |
1 files changed, 172 insertions, 0 deletions
diff --git a/libtomcrypt/src/pk/ecc/ecc_import.c b/libtomcrypt/src/pk/ecc/ecc_import.c new file mode 100644 index 0000000..4adb28e --- /dev/null +++ b/libtomcrypt/src/pk/ecc/ecc_import.c @@ -0,0 +1,172 @@ +/* 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, tomstdenis@gmail.com, 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 $ */ + |