From: Sergey Matveev <stargrave@stargrave.org>
Date: Tue, 16 Nov 2021 15:35:14 +0000 (+0300)
Subject: More thread-safe gost3410
X-Git-Tag: v5.9.0^0
X-Git-Url: http://www.git.cypherpunks.ru/?p=gogost.git;a=commitdiff_plain;h=7bed9561c7c09958ad1268b397058431fd3362bc

More thread-safe gost3410
---

diff --git a/gogost.go b/gogost.go
index 7df53a2..dab79d3 100644
--- a/gogost.go
+++ b/gogost.go
@@ -1,4 +1,4 @@
 // Pure Go GOST cryptographic functions library.
 package gogost
 
-const Version = "5.8.0"
+const Version = "5.9.0"
diff --git a/gost3410/curve.go b/gost3410/curve.go
index 1aa783c..a5f8d51 100644
--- a/gost3410/curve.go
+++ b/gost3410/curve.go
@@ -48,11 +48,6 @@ type Curve struct {
 	X *big.Int
 	Y *big.Int
 
-	// Temporary variable for the add method
-	t  *big.Int
-	tx *big.Int
-	ty *big.Int
-
 	// Cached s/t parameters for Edwards curve points conversion
 	edS *big.Int
 	edT *big.Int
@@ -67,9 +62,6 @@ func NewCurve(p, q, a, b, x, y, e, d, co *big.Int) (*Curve, error) {
 		B:    b,
 		X:    x,
 		Y:    y,
-		t:    big.NewInt(0),
-		tx:   big.NewInt(0),
-		ty:   big.NewInt(0),
 	}
 	r1 := big.NewInt(0)
 	r2 := big.NewInt(0)
@@ -107,38 +99,39 @@ func (c *Curve) pos(v *big.Int) {
 }
 
 func (c *Curve) add(p1x, p1y, p2x, p2y *big.Int) {
+	var t, tx, ty big.Int
 	if p1x.Cmp(p2x) == 0 && p1y.Cmp(p2y) == 0 {
 		// double
-		c.t.Mul(p1x, p1x)
-		c.t.Mul(c.t, bigInt3)
-		c.t.Add(c.t, c.A)
-		c.tx.Mul(bigInt2, p1y)
-		c.tx.ModInverse(c.tx, c.P)
-		c.t.Mul(c.t, c.tx)
-		c.t.Mod(c.t, c.P)
+		t.Mul(p1x, p1x)
+		t.Mul(&t, bigInt3)
+		t.Add(&t, c.A)
+		tx.Mul(bigInt2, p1y)
+		tx.ModInverse(&tx, c.P)
+		t.Mul(&t, &tx)
+		t.Mod(&t, c.P)
 	} else {
-		c.tx.Sub(p2x, p1x)
-		c.tx.Mod(c.tx, c.P)
-		c.pos(c.tx)
-		c.ty.Sub(p2y, p1y)
-		c.ty.Mod(c.ty, c.P)
-		c.pos(c.ty)
-		c.t.ModInverse(c.tx, c.P)
-		c.t.Mul(c.t, c.ty)
-		c.t.Mod(c.t, c.P)
+		tx.Sub(p2x, p1x)
+		tx.Mod(&tx, c.P)
+		c.pos(&tx)
+		ty.Sub(p2y, p1y)
+		ty.Mod(&ty, c.P)
+		c.pos(&ty)
+		t.ModInverse(&tx, c.P)
+		t.Mul(&t, &ty)
+		t.Mod(&t, c.P)
 	}
-	c.tx.Mul(c.t, c.t)
-	c.tx.Sub(c.tx, p1x)
-	c.tx.Sub(c.tx, p2x)
-	c.tx.Mod(c.tx, c.P)
-	c.pos(c.tx)
-	c.ty.Sub(p1x, c.tx)
-	c.ty.Mul(c.ty, c.t)
-	c.ty.Sub(c.ty, p1y)
-	c.ty.Mod(c.ty, c.P)
-	c.pos(c.ty)
-	p1x.Set(c.tx)
-	p1y.Set(c.ty)
+	tx.Mul(&t, &t)
+	tx.Sub(&tx, p1x)
+	tx.Sub(&tx, p2x)
+	tx.Mod(&tx, c.P)
+	c.pos(&tx)
+	ty.Sub(p1x, &tx)
+	ty.Mul(&ty, &t)
+	ty.Sub(&ty, p1y)
+	ty.Mod(&ty, c.P)
+	c.pos(&ty)
+	p1x.Set(&tx)
+	p1y.Set(&ty)
 }
 
 func (c *Curve) Exp(degree, xS, yS *big.Int) (*big.Int, *big.Int, error) {
diff --git a/gost3410/edwards.go b/gost3410/edwards.go
index 43484e0..9cefec6 100644
--- a/gost3410/edwards.go
+++ b/gost3410/edwards.go
@@ -31,62 +31,65 @@ func (c *Curve) EdwardsST() (*big.Int, *big.Int) {
 	c.edS.Set(c.E)
 	c.edS.Sub(c.edS, c.D)
 	c.pos(c.edS)
-	c.t.SetUint64(4)
-	c.t.ModInverse(c.t, c.P)
-	c.edS.Mul(c.edS, c.t)
+	var t big.Int
+	t.SetUint64(4)
+	t.ModInverse(&t, c.P)
+	c.edS.Mul(c.edS, &t)
 	c.edS.Mod(c.edS, c.P)
 	c.edT = big.NewInt(0)
 	c.edT.Set(c.E)
 	c.edT.Add(c.edT, c.D)
-	c.t.SetUint64(6)
-	c.t.ModInverse(c.t, c.P)
-	c.edT.Mul(c.edT, c.t)
+	t.SetUint64(6)
+	t.ModInverse(&t, c.P)
+	c.edT.Mul(c.edT, &t)
 	c.edT.Mod(c.edT, c.P)
 	return c.edS, c.edT
 }
 
 // Convert Weierstrass X,Y coordinates to twisted Edwards U,V
-func XY2UV(curve *Curve, x, y *big.Int) (*big.Int, *big.Int) {
-	if !curve.IsEdwards() {
+func XY2UV(c *Curve, x, y *big.Int) (*big.Int, *big.Int) {
+	if !c.IsEdwards() {
 		panic("non twisted Edwards curve")
 	}
-	edS, edT := curve.EdwardsST()
-	curve.t.Sub(x, edT)
-	curve.pos(curve.t)
+	edS, edT := c.EdwardsST()
+	var t big.Int
+	t.Sub(x, edT)
+	c.pos(&t)
 	u := big.NewInt(0)
-	u.ModInverse(y, curve.P)
-	u.Mul(u, curve.t)
-	u.Mod(u, curve.P)
-	v := big.NewInt(0).Set(curve.t)
+	u.ModInverse(y, c.P)
+	u.Mul(u, &t)
+	u.Mod(u, c.P)
+	v := big.NewInt(0).Set(&t)
 	v.Sub(v, edS)
-	curve.pos(v)
-	curve.t.Add(curve.t, edS)
-	curve.t.ModInverse(curve.t, curve.P)
-	v.Mul(v, curve.t)
-	v.Mod(v, curve.P)
+	c.pos(v)
+	t.Add(&t, edS)
+	t.ModInverse(&t, c.P)
+	v.Mul(v, &t)
+	v.Mod(v, c.P)
 	return u, v
 }
 
 // Convert twisted Edwards U,V coordinates to Weierstrass X,Y
-func UV2XY(curve *Curve, u, v *big.Int) (*big.Int, *big.Int) {
-	if !curve.IsEdwards() {
+func UV2XY(c *Curve, u, v *big.Int) (*big.Int, *big.Int) {
+	if !c.IsEdwards() {
 		panic("non twisted Edwards curve")
 	}
-	edS, edT := curve.EdwardsST()
-	curve.tx.Add(bigInt1, v)
-	curve.tx.Mul(curve.tx, edS)
-	curve.tx.Mod(curve.tx, curve.P)
-	curve.ty.Sub(bigInt1, v)
-	curve.pos(curve.ty)
+	edS, edT := c.EdwardsST()
+	var tx, ty big.Int
+	tx.Add(bigInt1, v)
+	tx.Mul(&tx, edS)
+	tx.Mod(&tx, c.P)
+	ty.Sub(bigInt1, v)
+	c.pos(&ty)
 	x := big.NewInt(0)
-	x.ModInverse(curve.ty, curve.P)
-	x.Mul(x, curve.tx)
+	x.ModInverse(&ty, c.P)
+	x.Mul(x, &tx)
 	x.Add(x, edT)
-	x.Mod(x, curve.P)
+	x.Mod(x, c.P)
 	y := big.NewInt(0)
-	y.Mul(u, curve.ty)
-	y.ModInverse(y, curve.P)
-	y.Mul(y, curve.tx)
-	y.Mod(y, curve.P)
+	y.Mul(u, &ty)
+	y.ModInverse(y, c.P)
+	y.Mul(y, &tx)
+	y.Mod(y, c.P)
 	return x, y
 }
diff --git a/news.texi b/news.texi
index 049ee1f..3ffaae9 100644
--- a/news.texi
+++ b/news.texi
@@ -3,6 +3,10 @@
 
 @table @strong
 
+@anchor{Release 5.9.0}
+@item 5.9.0
+@code{gost3410} is more thread-safe.
+
 @anchor{Release 5.8.0}
 @item 5.8.0
 Faster Kuznechik and ~3x faster Kuznechik-MGM.