1 files changed, 224 insertions, 0 deletions
diff --git a/src/crypto/internal/boring/ecdh.go b/src/crypto/internal/boring/ecdh.go
new file mode 100644
index 0000000..8f46d81
--- /dev/null
+++ b/src/crypto/internal/boring/ecdh.go
@@ -0,0 +1,224 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build boringcrypto && linux && (amd64 || arm64) && !android && !cmd_go_bootstrap && !msan
+
+package boring
+
+// #include "goboringcrypto.h"
+import "C"
+import (
+	"errors"
+	"runtime"
+	"unsafe"
+)
+
+type PublicKeyECDH struct {
+	curve string
+	key   *C.GO_EC_POINT
+	group *C.GO_EC_GROUP
+	bytes []byte
+}
+
+func (k *PublicKeyECDH) finalize() {
+	C._goboringcrypto_EC_POINT_free(k.key)
+}
+
+type PrivateKeyECDH struct {
+	curve string
+	key   *C.GO_EC_KEY
+}
+
+func (k *PrivateKeyECDH) finalize() {
+	C._goboringcrypto_EC_KEY_free(k.key)
+}
+
+func NewPublicKeyECDH(curve string, bytes []byte) (*PublicKeyECDH, error) {
+	if len(bytes) < 1 {
+		return nil, errors.New("NewPublicKeyECDH: missing key")
+	}
+
+	nid, err := curveNID(curve)
+	if err != nil {
+		return nil, err
+	}
+
+	group := C._goboringcrypto_EC_GROUP_new_by_curve_name(nid)
+	if group == nil {
+		return nil, fail("EC_GROUP_new_by_curve_name")
+	}
+	defer C._goboringcrypto_EC_GROUP_free(group)
+	key := C._goboringcrypto_EC_POINT_new(group)
+	if key == nil {
+		return nil, fail("EC_POINT_new")
+	}
+	ok := C._goboringcrypto_EC_POINT_oct2point(group, key, (*C.uint8_t)(unsafe.Pointer(&bytes[0])), C.size_t(len(bytes)), nil) != 0
+	if !ok {
+		C._goboringcrypto_EC_POINT_free(key)
+		return nil, errors.New("point not on curve")
+	}
+
+	k := &PublicKeyECDH{curve, key, group, append([]byte(nil), bytes...)}
+	// Note: Because of the finalizer, any time k.key is passed to cgo,
+	// that call must be followed by a call to runtime.KeepAlive(k),
+	// to make sure k is not collected (and finalized) before the cgo
+	// call returns.
+	runtime.SetFinalizer(k, (*PublicKeyECDH).finalize)
+	return k, nil
+}
+
+func (k *PublicKeyECDH) Bytes() []byte { return k.bytes }
+
+func NewPrivateKeyECDH(curve string, bytes []byte) (*PrivateKeyECDH, error) {
+	nid, err := curveNID(curve)
+	if err != nil {
+		return nil, err
+	}
+	key := C._goboringcrypto_EC_KEY_new_by_curve_name(nid)
+	if key == nil {
+		return nil, fail("EC_KEY_new_by_curve_name")
+	}
+	b := bytesToBN(bytes)
+	ok := b != nil && C._goboringcrypto_EC_KEY_set_private_key(key, b) != 0
+	if b != nil {
+		C._goboringcrypto_BN_free(b)
+	}
+	if !ok {
+		C._goboringcrypto_EC_KEY_free(key)
+		return nil, fail("EC_KEY_set_private_key")
+	}
+	k := &PrivateKeyECDH{curve, key}
+	// Note: Same as in NewPublicKeyECDH regarding finalizer and KeepAlive.
+	runtime.SetFinalizer(k, (*PrivateKeyECDH).finalize)
+	return k, nil
+}
+
+func (k *PrivateKeyECDH) PublicKey() (*PublicKeyECDH, error) {
+	defer runtime.KeepAlive(k)
+
+	group := C._goboringcrypto_EC_KEY_get0_group(k.key)
+	if group == nil {
+		return nil, fail("EC_KEY_get0_group")
+	}
+	kbig := C._goboringcrypto_EC_KEY_get0_private_key(k.key)
+	if kbig == nil {
+		return nil, fail("EC_KEY_get0_private_key")
+	}
+	pt := C._goboringcrypto_EC_POINT_new(group)
+	if pt == nil {
+		return nil, fail("EC_POINT_new")
+	}
+	if C._goboringcrypto_EC_POINT_mul(group, pt, kbig, nil, nil, nil) == 0 {
+		C._goboringcrypto_EC_POINT_free(pt)
+		return nil, fail("EC_POINT_mul")
+	}
+	bytes, err := pointBytesECDH(k.curve, group, pt)
+	if err != nil {
+		C._goboringcrypto_EC_POINT_free(pt)
+		return nil, err
+	}
+	pub := &PublicKeyECDH{k.curve, pt, group, bytes}
+	// Note: Same as in NewPublicKeyECDH regarding finalizer and KeepAlive.
+	runtime.SetFinalizer(pub, (*PublicKeyECDH).finalize)
+	return pub, nil
+}
+
+func pointBytesECDH(curve string, group *C.GO_EC_GROUP, pt *C.GO_EC_POINT) ([]byte, error) {
+	out := make([]byte, 1+2*curveSize(curve))
+	n := C._goboringcrypto_EC_POINT_point2oct(group, pt, C.GO_POINT_CONVERSION_UNCOMPRESSED, (*C.uint8_t)(unsafe.Pointer(&out[0])), C.size_t(len(out)), nil)
+	if int(n) != len(out) {
+		return nil, fail("EC_POINT_point2oct")
+	}
+	return out, nil
+}
+
+func ECDH(priv *PrivateKeyECDH, pub *PublicKeyECDH) ([]byte, error) {
+	group := C._goboringcrypto_EC_KEY_get0_group(priv.key)
+	if group == nil {
+		return nil, fail("EC_KEY_get0_group")
+	}
+	privBig := C._goboringcrypto_EC_KEY_get0_private_key(priv.key)
+	if privBig == nil {
+		return nil, fail("EC_KEY_get0_private_key")
+	}
+	pt := C._goboringcrypto_EC_POINT_new(group)
+	if pt == nil {
+		return nil, fail("EC_POINT_new")
+	}
+	defer C._goboringcrypto_EC_POINT_free(pt)
+	if C._goboringcrypto_EC_POINT_mul(group, pt, nil, pub.key, privBig, nil) == 0 {
+		return nil, fail("EC_POINT_mul")
+	}
+	out, err := xCoordBytesECDH(priv.curve, group, pt)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
+func xCoordBytesECDH(curve string, group *C.GO_EC_GROUP, pt *C.GO_EC_POINT) ([]byte, error) {
+	big := C._goboringcrypto_BN_new()
+	defer C._goboringcrypto_BN_free(big)
+	if C._goboringcrypto_EC_POINT_get_affine_coordinates_GFp(group, pt, big, nil, nil) == 0 {
+		return nil, fail("EC_POINT_get_affine_coordinates_GFp")
+	}
+	return bigBytesECDH(curve, big)
+}
+
+func bigBytesECDH(curve string, big *C.GO_BIGNUM) ([]byte, error) {
+	out := make([]byte, curveSize(curve))
+	if C._goboringcrypto_BN_bn2bin_padded((*C.uint8_t)(&out[0]), C.size_t(len(out)), big) == 0 {
+		return nil, fail("BN_bn2bin_padded")
+	}
+	return out, nil
+}
+
+func curveSize(curve string) int {
+	switch curve {
+	default:
+		panic("crypto/internal/boring: unknown curve " + curve)
+	case "P-256":
+		return 256 / 8
+	case "P-384":
+		return 384 / 8
+	case "P-521":
+		return (521 + 7) / 8
+	}
+}
+
+func GenerateKeyECDH(curve string) (*PrivateKeyECDH, []byte, error) {
+	nid, err := curveNID(curve)
+	if err != nil {
+		return nil, nil, err
+	}
+	key := C._goboringcrypto_EC_KEY_new_by_curve_name(nid)
+	if key == nil {
+		return nil, nil, fail("EC_KEY_new_by_curve_name")
+	}
+	if C._goboringcrypto_EC_KEY_generate_key_fips(key) == 0 {
+		C._goboringcrypto_EC_KEY_free(key)
+		return nil, nil, fail("EC_KEY_generate_key_fips")
+	}
+
+	group := C._goboringcrypto_EC_KEY_get0_group(key)
+	if group == nil {
+		C._goboringcrypto_EC_KEY_free(key)
+		return nil, nil, fail("EC_KEY_get0_group")
+	}
+	b := C._goboringcrypto_EC_KEY_get0_private_key(key)
+	if b == nil {
+		C._goboringcrypto_EC_KEY_free(key)
+		return nil, nil, fail("EC_KEY_get0_private_key")
+	}
+	bytes, err := bigBytesECDH(curve, b)
+	if err != nil {
+		C._goboringcrypto_EC_KEY_free(key)
+		return nil, nil, err
+	}
+
+	k := &PrivateKeyECDH{curve, key}
+	// Note: Same as in NewPublicKeyECDH regarding finalizer and KeepAlive.
+	runtime.SetFinalizer(k, (*PrivateKeyECDH).finalize)
+	return k, bytes, nil
+}