ec.go

//go:build !cmd_go_bootstrap

package openssl

// #include "goopenssl.h"
import "C"

func curveNID(curve string) C.int {
	switch curve {
	case "P-224":
		return C.GO_NID_secp224r1
	case "P-256":
		return C.GO_NID_X9_62_prime256v1
	case "P-384":
		return C.GO_NID_secp384r1
	case "P-521":
		return C.GO_NID_secp521r1
	default:
		panic("openssl: unknown curve " + curve)
	}
}

// curveSize returns the size of the curve in bytes.
func curveSize(curve string) int {
	switch curve {
	case "P-224":
		return 224 / 8
	case "P-256":
		return 256 / 8
	case "P-384":
		return 384 / 8
	case "P-521":
		return (521 + 7) / 8
	default:
		panic("openssl: unknown curve " + curve)
	}
}

// encodeEcPoint encodes pt.
func encodeEcPoint(group C.GO_EC_GROUP_PTR, pt C.GO_EC_POINT_PTR) ([]byte, error) {
	// Get encoded point size.
	n := C.go_openssl_EC_POINT_point2oct(group, pt, C.GO_POINT_CONVERSION_UNCOMPRESSED, nil, 0, nil)
	if n == 0 {
		return nil, newOpenSSLError("EC_POINT_point2oct")
	}
	// Encode point into bytes.
	bytes := make([]byte, n)
	n = C.go_openssl_EC_POINT_point2oct(group, pt, C.GO_POINT_CONVERSION_UNCOMPRESSED, base(bytes), n, nil)
	if n == 0 {
		return nil, newOpenSSLError("EC_POINT_point2oct")
	}
	return bytes, nil
}

// generateAndEncodeEcPublicKey calls newPubKeyPointFn to generate a public key point and then encodes it.
func generateAndEncodeEcPublicKey(nid C.int, newPubKeyPointFn func(group C.GO_EC_GROUP_PTR) (C.GO_EC_POINT_PTR, error)) ([]byte, error) {
	group := C.go_openssl_EC_GROUP_new_by_curve_name(nid)
	if group == nil {
		return nil, newOpenSSLError("EC_GROUP_new_by_curve_name")
	}
	defer C.go_openssl_EC_GROUP_free(group)
	pt, err := newPubKeyPointFn(group)
	if err != nil {
		return nil, err
	}
	defer C.go_openssl_EC_POINT_free(pt)
	return encodeEcPoint(group, pt)
}