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);
}
ECDH_DATA *ecdh_check(EC_KEY *key)
{
ECDH_DATA *ecdh_data;
void *data = EC_KEY_get_key_method_data(key, ecdh_data_dup,
ecdh_data_free, ecdh_data_free);
if (data == NULL) {
ecdh_data = (ECDH_DATA *)ecdh_data_new();
if (ecdh_data == NULL)
return NULL;
data = EC_KEY_insert_key_method_data(key, (void *)ecdh_data,
ecdh_data_dup, ecdh_data_free,
ecdh_data_free);
if (data != NULL) {
/*
* Another thread raced us to install the key_method data and
* won.
*/
ecdh_data_free(ecdh_data);
ecdh_data = (ECDH_DATA *)data;
}
} else
ecdh_data = (ECDH_DATA *)data;
#ifdef OPENSSL_FIPS
if (FIPS_mode() && !(ecdh_data->flags & ECDH_FLAG_FIPS_METHOD)
&& !(EC_KEY_get_flags(key) & EC_FLAG_NON_FIPS_ALLOW)) {
ECDHerr(ECDH_F_ECDH_CHECK, ECDH_R_NON_FIPS_METHOD);
return NULL;
}
#endif
return ecdh_data;
}
/* This implementation is based on the following primitives in the IEEE 1363 standard:
* - ECKAS-DH1
* - ECSVDP-DH
* Finally an optional KDF is applied.
*/
static int ecdh_compute_key(void *out, size_t outlen, const EC_POINT *pub_key,
EC_KEY *ecdh,
void *(*KDF)(const void *in, size_t inlen, void *out, size_t *outlen))
{
BN_CTX *ctx;
EC_POINT *tmp=NULL;
BIGNUM *x=NULL, *y=NULL;
const BIGNUM *priv_key;
const EC_GROUP* group;
int ret= -1;
size_t buflen, len;
unsigned char *buf=NULL;
if (outlen > INT_MAX)
{
ECDHerr(ECDH_F_ECDH_COMPUTE_KEY,ERR_R_MALLOC_FAILURE); /* sort of, anyway */
return -1;
}
if ((ctx = BN_CTX_new()) == NULL) goto err;
BN_CTX_start(ctx);
x = BN_CTX_get(ctx);
y = BN_CTX_get(ctx);
priv_key = EC_KEY_get0_private_key(ecdh);
if (priv_key == NULL)
{
ECDHerr(ECDH_F_ECDH_COMPUTE_KEY,ECDH_R_NO_PRIVATE_VALUE);
goto err;
}
group = EC_KEY_get0_group(ecdh);
if ((tmp=EC_POINT_new(group)) == NULL)
{
ECDHerr(ECDH_F_ECDH_COMPUTE_KEY,ERR_R_MALLOC_FAILURE);
goto err;
}
if (!EC_POINT_mul(group, tmp, NULL, pub_key, priv_key, ctx))
{
ECDHerr(ECDH_F_ECDH_COMPUTE_KEY,ECDH_R_POINT_ARITHMETIC_FAILURE);
goto err;
}
if (EC_METHOD_get_field_type(EC_GROUP_method_of(group)) == NID_X9_62_prime_field)
{
if (!EC_POINT_get_affine_coordinates_GFp(group, tmp, x, y, ctx))
{
ECDHerr(ECDH_F_ECDH_COMPUTE_KEY,ECDH_R_POINT_ARITHMETIC_FAILURE);
goto err;
}
}
#ifndef OPENSSL_NO_EC2M
else
{
if (!EC_POINT_get_affine_coordinates_GF2m(group, tmp, x, y, ctx))
{
ECDHerr(ECDH_F_ECDH_COMPUTE_KEY,ECDH_R_POINT_ARITHMETIC_FAILURE);
goto err;
}
}
#endif
buflen = (EC_GROUP_get_degree(group) + 7)/8;
len = BN_num_bytes(x);
if (len > buflen)
{
ECDHerr(ECDH_F_ECDH_COMPUTE_KEY,ERR_R_INTERNAL_ERROR);
goto err;
}
if ((buf = malloc(buflen)) == NULL)
{
ECDHerr(ECDH_F_ECDH_COMPUTE_KEY,ERR_R_MALLOC_FAILURE);
goto err;
}
memset(buf, 0, buflen - len);
if (len != (size_t)BN_bn2bin(x, buf + buflen - len))
{
ECDHerr(ECDH_F_ECDH_COMPUTE_KEY,ERR_R_BN_LIB);
goto err;
}
if (KDF != 0)
{
if (KDF(buf, buflen, out, &outlen) == NULL)
{
ECDHerr(ECDH_F_ECDH_COMPUTE_KEY,ECDH_R_KDF_FAILED);
goto err;
}
ret = outlen;
}
else
{
/* no KDF, just copy as much as we can */
if (outlen > buflen)
outlen = buflen;
memcpy(out, buf, outlen);
ret = outlen;
}
err:
EC_POINT_free(tmp);
if (ctx)
BN_CTX_end(ctx);
BN_CTX_free(ctx);
free(buf);
return(ret);
}
