diff options
Diffstat (limited to 'src/pk/ecc/ecc_encrypt_key.c')
| -rw-r--r-- | src/pk/ecc/ecc_encrypt_key.c | 136 |
1 files changed, 136 insertions, 0 deletions
diff --git a/src/pk/ecc/ecc_encrypt_key.c b/src/pk/ecc/ecc_encrypt_key.c new file mode 100644 index 0000000..dd9bab0 --- /dev/null +++ b/src/pk/ecc/ecc_encrypt_key.c @@ -0,0 +1,136 @@ +/* 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_encrypt_key.c + ECC Crypto, Tom St Denis +*/ + +#ifdef MECC + +/** + Encrypt a symmetric key with ECC + @param in The symmetric key you want to encrypt + @param inlen The length of the key to encrypt (octets) + @param out [out] The destination for the ciphertext + @param outlen [in/out] The max size and resulting size of the ciphertext + @param prng An active PRNG state + @param wprng The index of the PRNG you wish to use + @param hash The index of the hash you want to use + @param key The ECC key you want to encrypt to + @return CRYPT_OK if successful +*/ +int ecc_encrypt_key(const unsigned char *in, unsigned long inlen, + unsigned char *out, unsigned long *outlen, + prng_state *prng, int wprng, int hash, + ecc_key *key) +{ + unsigned char *pub_expt, *ecc_shared, *skey; + ecc_key pubkey; + unsigned long x, y, pubkeysize; + int err; + + LTC_ARGCHK(in != NULL); + LTC_ARGCHK(out != NULL); + LTC_ARGCHK(outlen != NULL); + LTC_ARGCHK(key != NULL); + + /* check that wprng/cipher/hash are not invalid */ + if ((err = prng_is_valid(wprng)) != CRYPT_OK) { + return err; + } + + if ((err = hash_is_valid(hash)) != CRYPT_OK) { + return err; + } + + if (inlen > hash_descriptor[hash].hashsize) { + return CRYPT_INVALID_HASH; + } + + /* make a random key and export the public copy */ + if ((err = ecc_make_key_ex(prng, wprng, &pubkey, key->dp)) != CRYPT_OK) { + return err; + } + + pub_expt = XMALLOC(ECC_BUF_SIZE); + ecc_shared = XMALLOC(ECC_BUF_SIZE); + skey = XMALLOC(MAXBLOCKSIZE); + if (pub_expt == NULL || ecc_shared == NULL || skey == NULL) { + if (pub_expt != NULL) { + XFREE(pub_expt); + } + if (ecc_shared != NULL) { + XFREE(ecc_shared); + } + if (skey != NULL) { + XFREE(skey); + } + ecc_free(&pubkey); + return CRYPT_MEM; + } + + pubkeysize = ECC_BUF_SIZE; + if ((err = ecc_export(pub_expt, &pubkeysize, PK_PUBLIC, &pubkey)) != CRYPT_OK) { + ecc_free(&pubkey); + goto LBL_ERR; + } + + /* make random key */ + x = ECC_BUF_SIZE; + if ((err = ecc_shared_secret(&pubkey, key, ecc_shared, &x)) != CRYPT_OK) { + ecc_free(&pubkey); + goto LBL_ERR; + } + ecc_free(&pubkey); + y = MAXBLOCKSIZE; + if ((err = hash_memory(hash, ecc_shared, x, skey, &y)) != CRYPT_OK) { + goto LBL_ERR; + } + + /* Encrypt key */ + for (x = 0; x < inlen; x++) { + skey[x] ^= in[x]; + } + + err = der_encode_sequence_multi(out, outlen, + LTC_ASN1_OBJECT_IDENTIFIER, hash_descriptor[hash].OIDlen, hash_descriptor[hash].OID, + LTC_ASN1_OCTET_STRING, pubkeysize, pub_expt, + LTC_ASN1_OCTET_STRING, inlen, skey, + LTC_ASN1_EOL, 0UL, NULL); + +LBL_ERR: +#ifdef LTC_CLEAN_STACK + /* clean up */ + zeromem(pub_expt, ECC_BUF_SIZE); + zeromem(ecc_shared, ECC_BUF_SIZE); + zeromem(skey, MAXBLOCKSIZE); +#endif + + XFREE(skey); + XFREE(ecc_shared); + XFREE(pub_expt); + + return err; +} + +#endif +/* $Source: /cvs/libtom/libtomcrypt/src/pk/ecc/ecc_encrypt_key.c,v $ */ +/* $Revision: 1.4 $ */ +/* $Date: 2006/11/21 00:10:18 $ */ + |