static int ssl_ec_point_offer(SSL_ECDH_CTX *ctx, CBB *out) {
assert(ctx->data == NULL);
BIGNUM *private_key = BN_new();
if (private_key == NULL) {
return 0;
}
ctx->data = private_key;
/* Set up a shared |BN_CTX| for all operations. */
BN_CTX *bn_ctx = BN_CTX_new();
if (bn_ctx == NULL) {
return 0;
}
BN_CTX_start(bn_ctx);
int ret = 0;
EC_POINT *public_key = NULL;
EC_GROUP *group = EC_GROUP_new_by_curve_name(ctx->method->nid);
if (group == NULL) {
goto err;
}
/* Generate a private key. */
const BIGNUM *order = EC_GROUP_get0_order(group);
do {
if (!BN_rand_range(private_key, order)) {
goto err;
}
} while (BN_is_zero(private_key));
/* Compute the corresponding public key and serialize it. */
public_key = EC_POINT_new(group);
if (public_key == NULL ||
!EC_POINT_mul(group, public_key, private_key, NULL, NULL, bn_ctx) ||
!EC_POINT_point2cbb(out, group, public_key, POINT_CONVERSION_UNCOMPRESSED,
bn_ctx)) {
goto err;
}
ret = 1;
err:
EC_GROUP_free(group);
EC_POINT_free(public_key);
BN_CTX_end(bn_ctx);
BN_CTX_free(bn_ctx);
return ret;
}
static int eckey_pub_encode(CBB *out, const EVP_PKEY *key) {
const EC_KEY *ec_key = key->pkey.ec;
const EC_GROUP *group = EC_KEY_get0_group(ec_key);
const EC_POINT *public_key = EC_KEY_get0_public_key(ec_key);
// See RFC 5480, section 2.
CBB spki, algorithm, oid, key_bitstring;
if (!CBB_add_asn1(out, &spki, CBS_ASN1_SEQUENCE) ||
!CBB_add_asn1(&spki, &algorithm, CBS_ASN1_SEQUENCE) ||
!CBB_add_asn1(&algorithm, &oid, CBS_ASN1_OBJECT) ||
!CBB_add_bytes(&oid, ec_asn1_meth.oid, ec_asn1_meth.oid_len) ||
!EC_KEY_marshal_curve_name(&algorithm, group) ||
!CBB_add_asn1(&spki, &key_bitstring, CBS_ASN1_BITSTRING) ||
!CBB_add_u8(&key_bitstring, 0 /* padding */) ||
!EC_POINT_point2cbb(&key_bitstring, group, public_key,
POINT_CONVERSION_UNCOMPRESSED, NULL) ||
!CBB_flush(out)) {
OPENSSL_PUT_ERROR(EVP, EVP_R_ENCODE_ERROR);
return 0;
}
return 1;
}
