X-Git-Url: http://www.git.cypherpunks.ru/?a=blobdiff_plain;f=gost3410%2Fcurve.go;h=9ec14ded1de85e6760d63f3f7cfb9f7b965eaeab;hb=6d9056bfe4a2d69469a1e70f3bf08f89b377b06e;hp=696beabed9a68889675f9b96237a924fff30ea91;hpb=c40d1e5634cf6d540d908a57423f4b504e39f186;p=gogost.git

diff --git a/gost3410/curve.go b/gost3410/curve.go
index 696beab..9ec14de 100644
--- a/gost3410/curve.go
+++ b/gost3410/curve.go
@@ -1,5 +1,5 @@
 // GoGOST -- Pure Go GOST cryptographic functions library
-// Copyright (C) 2015-2020 Sergey Matveev <stargrave@stargrave.org>
+// Copyright (C) 2015-2021 Sergey Matveev <stargrave@stargrave.org>
 //
 // This program is free software: you can redistribute it and/or modify
 // it under the terms of the GNU General Public License as published by
@@ -25,6 +25,7 @@ var (
 	bigInt1 *big.Int = big.NewInt(1)
 	bigInt2 *big.Int = big.NewInt(2)
 	bigInt3 *big.Int = big.NewInt(3)
+	bigInt4 *big.Int = big.NewInt(4)
 )
 
 type Curve struct {
@@ -33,6 +34,8 @@ type Curve struct {
 	P *big.Int // Characteristic of the underlying prime field
 	Q *big.Int // Elliptic curve subgroup order
 
+	Co *big.Int // Cofactor
+
 	// Equation coefficients of the elliptic curve in canonical form
 	A *big.Int
 	B *big.Int
@@ -55,7 +58,7 @@ type Curve struct {
 	edT *big.Int
 }
 
-func NewCurve(p, q, a, b, x, y, e, d *big.Int) (*Curve, error) {
+func NewCurve(p, q, a, b, x, y, e, d, co *big.Int) (*Curve, error) {
 	c := Curve{
 		Name: "unknown",
 		P:    p,
@@ -85,9 +88,18 @@ func NewCurve(p, q, a, b, x, y, e, d *big.Int) (*Curve, error) {
 		c.E = e
 		c.D = d
 	}
+	if co == nil {
+		c.Co = bigInt1
+	} else {
+		c.Co = co
+	}
 	return &c, nil
 }
 
+func (c *Curve) PointSize() int {
+	return PointSize(c.P)
+}
+
 func (c *Curve) pos(v *big.Int) {
 	if v.Cmp(zero) < 0 {
 		v.Add(v, c.P)