static ECDH_DATA *ECDH_DATA_new_method(ENGINE *engine)
{
ECDH_DATA *ret;
ret = OPENSSL_malloc(sizeof(*ret));
if (ret == NULL) {
ECDHerr(ECDH_F_ECDH_DATA_NEW_METHOD, ERR_R_MALLOC_FAILURE);
return (NULL);
}
ret->init = NULL;
ret->meth = ECDH_get_default_method();
ret->engine = engine;
#ifndef OPENSSL_NO_ENGINE
if (!ret->engine)
ret->engine = ENGINE_get_default_ECDH();
if (ret->engine) {
ret->meth = ENGINE_get_ECDH(ret->engine);
if (!ret->meth) {
ECDHerr(ECDH_F_ECDH_DATA_NEW_METHOD, ERR_R_ENGINE_LIB);
ENGINE_finish(ret->engine);
OPENSSL_free(ret);
return NULL;
}
}
#endif
ret->flags = ret->meth->flags;
CRYPTO_new_ex_data(CRYPTO_EX_INDEX_ECDH, ret, &ret->ex_data);
return (ret);
}
int
ecdh_gm_compute_key(PACE_CTX * ctx, const BUF_MEM * s, const BUF_MEM * in,
BN_CTX *bn_ctx)
{
int ret = 0;
BUF_MEM * mem_h = NULL;
BIGNUM * bn_s = NULL, *order = NULL, *cofactor = NULL;
EC_POINT * ecp_h = NULL, *ecp_g = NULL;
const ECDH_METHOD *default_method;
EC_GROUP *group = NULL;
EC_KEY *static_key = NULL, *ephemeral_key = NULL;
BN_CTX_start(bn_ctx);
check((ctx && ctx->static_key && s && ctx->ka_ctx), "Invalid arguments");
static_key = EVP_PKEY_get1_EC_KEY(ctx->static_key);
check(static_key, "could not get key object");
/* Extract group parameters */
group = EC_GROUP_dup(EC_KEY_get0_group(static_key));
order = BN_CTX_get(bn_ctx);
cofactor = BN_CTX_get(bn_ctx);
check(group && cofactor, "internal error");
if (!EC_GROUP_get_order(group, order, bn_ctx)
|| !EC_GROUP_get_cofactor(group, cofactor, bn_ctx))
goto err;
/* Convert nonce to BIGNUM */
bn_s = BN_bin2bn((unsigned char *) s->data, s->length, bn_s);
if (!bn_s)
goto err;
default_method = ECDH_get_default_method();
ECDH_set_default_method(ECDH_OpenSSL_Point());
/* complete the ECDH and get the resulting point h */
mem_h = ecdh_compute_key(ctx->static_key, in, bn_ctx);
ECDH_set_default_method(default_method);
ecp_h = EC_POINT_new(group);
if (!mem_h || !ecp_h || !EC_POINT_oct2point(group, ecp_h,
(unsigned char *) mem_h->data, mem_h->length, bn_ctx))
goto err;
/* map to new generator */
ecp_g = EC_POINT_new(group);
/* g' = g*s + h*1 */
if (!EC_POINT_mul(group, ecp_g, bn_s, ecp_h, BN_value_one(), bn_ctx))
goto err;
/* Initialize ephemeral parameters with parameters from the static key */
ephemeral_key = EC_KEY_dup(static_key);
if (!ephemeral_key)
goto err;
EVP_PKEY_set1_EC_KEY(ctx->ka_ctx->key, ephemeral_key);
/* configure the new EC_KEY */
if (!EC_GROUP_set_generator(group, ecp_g, order, cofactor)
|| !EC_GROUP_check(group, bn_ctx)
|| !EC_KEY_set_group(ephemeral_key, group))
goto err;
ret = 1;
err:
if (ecp_g)
EC_POINT_clear_free(ecp_g);
if (ecp_h)
EC_POINT_clear_free(ecp_h);
if (mem_h)
BUF_MEM_free(mem_h);
if (bn_s)
BN_clear_free(bn_s);
BN_CTX_end(bn_ctx);
/* Decrement reference count, keys are still available via PACE_CTX */
if (static_key)
EC_KEY_free(static_key);
if (ephemeral_key)
EC_KEY_free(ephemeral_key);
if (group)
EC_GROUP_clear_free(group);
return ret;
}
