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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, 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 $ */
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