1 files changed, 106 insertions, 0 deletions
diff --git a/src/crypto/ecdsa/boring.go b/src/crypto/ecdsa/boring.go
new file mode 100644
index 0000000..275c60b
--- /dev/null
+++ b/src/crypto/ecdsa/boring.go
@@ -0,0 +1,106 @@
+// Copyright 2017 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
+
+package ecdsa
+
+import (
+	"crypto/internal/boring"
+	"crypto/internal/boring/bbig"
+	"crypto/internal/boring/bcache"
+	"math/big"
+)
+
+// Cached conversions from Go PublicKey/PrivateKey to BoringCrypto.
+//
+// The first operation on a PublicKey or PrivateKey makes a parallel
+// BoringCrypto key and saves it in pubCache or privCache.
+//
+// We could just assume that once used in a Sign or Verify operation,
+// a particular key is never again modified, but that has not been a
+// stated assumption before. Just in case there is any existing code that
+// does modify the key between operations, we save the original values
+// alongside the cached BoringCrypto key and check that the real key
+// still matches before using the cached key. The theory is that the real
+// operations are significantly more expensive than the comparison.
+
+var pubCache bcache.Cache[PublicKey, boringPub]
+var privCache bcache.Cache[PrivateKey, boringPriv]
+
+func init() {
+	pubCache.Register()
+	privCache.Register()
+}
+
+type boringPub struct {
+	key  *boring.PublicKeyECDSA
+	orig PublicKey
+}
+
+func boringPublicKey(pub *PublicKey) (*boring.PublicKeyECDSA, error) {
+	b := pubCache.Get(pub)
+	if b != nil && publicKeyEqual(&b.orig, pub) {
+		return b.key, nil
+	}
+
+	b = new(boringPub)
+	b.orig = copyPublicKey(pub)
+	key, err := boring.NewPublicKeyECDSA(b.orig.Curve.Params().Name, bbig.Enc(b.orig.X), bbig.Enc(b.orig.Y))
+	if err != nil {
+		return nil, err
+	}
+	b.key = key
+	pubCache.Put(pub, b)
+	return key, nil
+}
+
+type boringPriv struct {
+	key  *boring.PrivateKeyECDSA
+	orig PrivateKey
+}
+
+func boringPrivateKey(priv *PrivateKey) (*boring.PrivateKeyECDSA, error) {
+	b := privCache.Get(priv)
+	if b != nil && privateKeyEqual(&b.orig, priv) {
+		return b.key, nil
+	}
+
+	b = new(boringPriv)
+	b.orig = copyPrivateKey(priv)
+	key, err := boring.NewPrivateKeyECDSA(b.orig.Curve.Params().Name, bbig.Enc(b.orig.X), bbig.Enc(b.orig.Y), bbig.Enc(b.orig.D))
+	if err != nil {
+		return nil, err
+	}
+	b.key = key
+	privCache.Put(priv, b)
+	return key, nil
+}
+
+func publicKeyEqual(k1, k2 *PublicKey) bool {
+	return k1.X != nil &&
+		k1.Curve.Params() == k2.Curve.Params() &&
+		k1.X.Cmp(k2.X) == 0 &&
+		k1.Y.Cmp(k2.Y) == 0
+}
+
+func privateKeyEqual(k1, k2 *PrivateKey) bool {
+	return publicKeyEqual(&k1.PublicKey, &k2.PublicKey) &&
+		k1.D.Cmp(k2.D) == 0
+}
+
+func copyPublicKey(k *PublicKey) PublicKey {
+	return PublicKey{
+		Curve: k.Curve,
+		X:     new(big.Int).Set(k.X),
+		Y:     new(big.Int).Set(k.Y),
+	}
+}
+
+func copyPrivateKey(k *PrivateKey) PrivateKey {
+	return PrivateKey{
+		PublicKey: copyPublicKey(&k.PublicKey),
+		D:         new(big.Int).Set(k.D),
+	}
+}