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https://github.com/Laupetin/OpenAssetTools.git
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135 lines
3.9 KiB
C
135 lines
3.9 KiB
C
/* LibTomCrypt, modular cryptographic library -- Tom St Denis
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*
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* LibTomCrypt is a library that provides various cryptographic
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* algorithms in a highly modular and flexible manner.
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*
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* The library is free for all purposes without any express
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* guarantee it works.
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*/
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/* Implements ECC over Z/pZ for curve y^2 = x^3 - 3x + b
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*
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* All curves taken from NIST recommendation paper of July 1999
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* Available at http://csrc.nist.gov/cryptval/dss.htm
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*/
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#include "tomcrypt.h"
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/**
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@file ecc_encrypt_key.c
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ECC Crypto, Tom St Denis
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*/
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#ifdef LTC_MECC
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/**
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Encrypt a symmetric key with ECC
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@param in The symmetric key you want to encrypt
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@param inlen The length of the key to encrypt (octets)
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@param out [out] The destination for the ciphertext
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@param outlen [in/out] The max size and resulting size of the ciphertext
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@param prng An active PRNG state
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@param wprng The index of the PRNG you wish to use
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@param hash The index of the hash you want to use
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@param key The ECC key you want to encrypt to
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@return CRYPT_OK if successful
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*/
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int ecc_encrypt_key(const unsigned char *in, unsigned long inlen,
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unsigned char *out, unsigned long *outlen,
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prng_state *prng, int wprng, int hash,
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ecc_key *key)
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{
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unsigned char *pub_expt, *ecc_shared, *skey;
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ecc_key pubkey;
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unsigned long x, y, pubkeysize;
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int err;
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LTC_ARGCHK(in != NULL);
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LTC_ARGCHK(out != NULL);
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LTC_ARGCHK(outlen != NULL);
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LTC_ARGCHK(key != NULL);
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/* check that wprng/cipher/hash are not invalid */
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if ((err = prng_is_valid(wprng)) != CRYPT_OK) {
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return err;
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}
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if ((err = hash_is_valid(hash)) != CRYPT_OK) {
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return err;
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}
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if (inlen > hash_descriptor[hash].hashsize) {
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return CRYPT_INVALID_HASH;
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}
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/* make a random key and export the public copy */
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if ((err = ecc_make_key_ex(prng, wprng, &pubkey, key->dp)) != CRYPT_OK) {
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return err;
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}
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pub_expt = XMALLOC(ECC_BUF_SIZE);
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ecc_shared = XMALLOC(ECC_BUF_SIZE);
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skey = XMALLOC(MAXBLOCKSIZE);
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if (pub_expt == NULL || ecc_shared == NULL || skey == NULL) {
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if (pub_expt != NULL) {
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XFREE(pub_expt);
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}
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if (ecc_shared != NULL) {
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XFREE(ecc_shared);
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}
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if (skey != NULL) {
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XFREE(skey);
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}
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ecc_free(&pubkey);
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return CRYPT_MEM;
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}
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pubkeysize = ECC_BUF_SIZE;
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if ((err = ecc_export(pub_expt, &pubkeysize, PK_PUBLIC, &pubkey)) != CRYPT_OK) {
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ecc_free(&pubkey);
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goto LBL_ERR;
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}
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/* make random key */
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x = ECC_BUF_SIZE;
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if ((err = ecc_shared_secret(&pubkey, key, ecc_shared, &x)) != CRYPT_OK) {
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ecc_free(&pubkey);
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goto LBL_ERR;
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}
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ecc_free(&pubkey);
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y = MAXBLOCKSIZE;
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if ((err = hash_memory(hash, ecc_shared, x, skey, &y)) != CRYPT_OK) {
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goto LBL_ERR;
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}
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/* Encrypt key */
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for (x = 0; x < inlen; x++) {
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skey[x] ^= in[x];
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}
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err = der_encode_sequence_multi(out, outlen,
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LTC_ASN1_OBJECT_IDENTIFIER, hash_descriptor[hash].OIDlen, hash_descriptor[hash].OID,
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LTC_ASN1_OCTET_STRING, pubkeysize, pub_expt,
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LTC_ASN1_OCTET_STRING, inlen, skey,
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LTC_ASN1_EOL, 0UL, NULL);
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LBL_ERR:
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#ifdef LTC_CLEAN_STACK
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/* clean up */
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zeromem(pub_expt, ECC_BUF_SIZE);
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zeromem(ecc_shared, ECC_BUF_SIZE);
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zeromem(skey, MAXBLOCKSIZE);
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#endif
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XFREE(skey);
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XFREE(ecc_shared);
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XFREE(pub_expt);
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return err;
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}
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#endif
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/* ref: HEAD -> master, tag: v1.18.2 */
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/* git commit: 7e7eb695d581782f04b24dc444cbfde86af59853 */
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/* commit time: 2018-07-01 22:49:01 +0200 */
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