From: Sergey Matveev <stargrave@stargrave.org>
Date: Mon, 7 Aug 2023 13:02:21 +0000 (+0300)
Subject: gost3410.Public/Private keys BE/LE marshalling
X-Git-Tag: v5.13.0~1
X-Git-Url: http://www.git.cypherpunks.ru/?p=gogost.git;a=commitdiff_plain;h=e077d5f903e233fbefed0815be21be5f8f482017

gost3410.Public/Private keys BE/LE marshalling
---

diff --git a/gogost.go b/gogost.go
index 496885e..b7d04d9 100644
--- a/gogost.go
+++ b/gogost.go
@@ -1,4 +1,4 @@
 // Pure Go GOST cryptographic functions library.
 package gogost
 
-const Version = "5.12.0"
+const Version = "5.13.0"
diff --git a/gost3410/private.go b/gost3410/private.go
index 983d8d2..18549a2 100644
--- a/gost3410/private.go
+++ b/gost3410/private.go
@@ -29,7 +29,7 @@ type PrivateKey struct {
 }
 
 // Unmarshal little-endian private key. "raw" must be c.PointSize() length.
-func NewPrivateKey(c *Curve, raw []byte) (*PrivateKey, error) {
+func NewPrivateKeyLE(c *Curve, raw []byte) (*PrivateKey, error) {
 	pointSize := c.PointSize()
 	if len(raw) != pointSize {
 		return nil, fmt.Errorf("gogost/gost3410: len(key)=%d != %d", len(raw), pointSize)
@@ -45,6 +45,24 @@ func NewPrivateKey(c *Curve, raw []byte) (*PrivateKey, error) {
 	return &PrivateKey{c, k.Mod(k, c.Q)}, nil
 }
 
+// Unmarshal big-endian private key. "raw" must be c.PointSize() length.
+func NewPrivateKeyBE(c *Curve, raw []byte) (*PrivateKey, error) {
+	pointSize := c.PointSize()
+	if len(raw) != pointSize {
+		return nil, fmt.Errorf("gogost/gost3410: len(key)=%d != %d", len(raw), pointSize)
+	}
+	k := bytes2big(raw)
+	if k.Cmp(zero) == 0 {
+		return nil, errors.New("gogost/gost3410: zero private key")
+	}
+	return &PrivateKey{c, k.Mod(k, c.Q)}, nil
+}
+
+// This is an alias for NewPrivateKeyLE().
+func NewPrivateKey(c *Curve, raw []byte) (*PrivateKey, error) {
+	return NewPrivateKeyLE(c, raw)
+}
+
 func GenPrivateKey(c *Curve, rand io.Reader) (*PrivateKey, error) {
 	raw := make([]byte, c.PointSize())
 	if _, err := io.ReadFull(rand, raw); err != nil {
@@ -54,12 +72,22 @@ func GenPrivateKey(c *Curve, rand io.Reader) (*PrivateKey, error) {
 }
 
 // Marshal little-endian private key. raw will be prv.C.PointSize() length.
-func (prv *PrivateKey) Raw() (raw []byte) {
+func (prv *PrivateKey) RawLE() (raw []byte) {
 	raw = pad(prv.Key.Bytes(), prv.C.PointSize())
 	reverse(raw)
 	return raw
 }
 
+// Marshal big-endian private key. raw will be prv.C.PointSize() length.
+func (prv *PrivateKey) RawBE() (raw []byte) {
+	return pad(prv.Key.Bytes(), prv.C.PointSize())
+}
+
+// This is an alias for RawLE().
+func (prv *PrivateKey) Raw() []byte {
+	return prv.RawLE()
+}
+
 func (prv *PrivateKey) PublicKey() (*PublicKey, error) {
 	x, y, err := prv.C.Exp(prv.Key, prv.C.X, prv.C.Y)
 	if err != nil {
diff --git a/gost3410/public.go b/gost3410/public.go
index d2c01bc..ef5926b 100644
--- a/gost3410/public.go
+++ b/gost3410/public.go
@@ -23,12 +23,11 @@ import (
 
 type PublicKey struct {
 	C *Curve
-	X *big.Int
-	Y *big.Int
+	X, Y *big.Int
 }
 
 // Unmarshal LE(X)||LE(Y) public key. "raw" must be 2*c.PointSize() length.
-func NewPublicKey(c *Curve, raw []byte) (*PublicKey, error) {
+func NewPublicKeyLE(c *Curve, raw []byte) (*PublicKey, error) {
 	pointSize := c.PointSize()
 	key := make([]byte, 2*pointSize)
 	if len(raw) != len(key) {
@@ -44,10 +43,28 @@ func NewPublicKey(c *Curve, raw []byte) (*PublicKey, error) {
 	}, nil
 }
 
+// Unmarshal BE(X)||BE(Y) public key. "raw" must be 2*c.PointSize() length.
+func NewPublicKeyBE(c *Curve, raw []byte) (*PublicKey, error) {
+	pointSize := c.PointSize()
+	if len(raw) != 2*pointSize {
+		return nil, fmt.Errorf("gogost/gost3410: len(key) != %d", 2*pointSize)
+	}
+	return &PublicKey{
+		c,
+		bytes2big(raw[:pointSize]),
+		bytes2big(raw[pointSize:]),
+	}, nil
+}
+
+// This is an alias for NewPublicKeyLE().
+func NewPublicKey(c *Curve, raw []byte) (*PublicKey, error) {
+	return NewPublicKeyLE(c, raw)
+}
+
 // Marshal LE(X)||LE(Y) public key. raw will be 2*pub.C.PointSize() length.
-func (pub *PublicKey) Raw() (raw []byte) {
+func (pub *PublicKey) RawLE() []byte {
 	pointSize := pub.C.PointSize()
-	raw = append(
+	raw := append(
 		pad(pub.Y.Bytes(), pointSize),
 		pad(pub.X.Bytes(), pointSize)...,
 	)
@@ -55,6 +72,20 @@ func (pub *PublicKey) Raw() (raw []byte) {
 	return raw
 }
 
+// Marshal BE(X)||BE(Y) public key. raw will be 2*pub.C.PointSize() length.
+func (pub *PublicKey) RawBE() []byte {
+	pointSize := pub.C.PointSize()
+	return append(
+		pad(pub.X.Bytes(), pointSize),
+		pad(pub.Y.Bytes(), pointSize)...,
+	)
+}
+
+// This is an alias for RawLE().
+func (pub *PublicKey) Raw() []byte {
+	return pub.RawLE()
+}
+
 func (pub *PublicKey) VerifyDigest(digest, signature []byte) (bool, error) {
 	pointSize := pub.C.PointSize()
 	if len(signature) != 2*pointSize {
diff --git a/news.texi b/news.texi
index 01a789a..022b9a6 100644
--- a/news.texi
+++ b/news.texi
@@ -3,6 +3,18 @@
 
 @table @strong
 
+@anchor{Release 5.13.0}
+@item 5.13.0
+    @itemize
+    @item
+        @code{gost3410.NewPublicKeyLE}, @code{gost3410.PublicKey.RawLE},
+        @code{gost3410.NewPublicKeyBE}, @code{gost3410.PublicKey.RawBE},
+        @code{gost3410.NewPrivateKeyLE}, @code{gost3410.PrivateKey.RawLE},
+        @code{gost3410.NewPrivateKeyBE}, @code{gost3410.PrivateKey.RawBE},
+        functions appeared, to simplify dealing with different endianness
+        keys serialisation
+    @end itemize
+
 @anchor{Release 5.12.0}
 @item 5.12.0
 Updated dependencies.