Merge pull request #13 from bytemare/lint

Test fixes

group/curve25519/element.go

@@ -107,6 +107,10 @@ func (e *Element) Decode(in []byte) (internal.Point, error) {
 		return nil, fmt.Errorf("decoding element : %w", err)
 	}
 
+	if e.IsIdentity() {
+		return nil, internal.ErrIdentity
+	}
+
 	return e, nil
 }
 

group/edwards25519/element.go

@@ -100,6 +100,10 @@ func (e *Element) Decode(in []byte) (internal.Point, error) {
 		return nil, fmt.Errorf("decoding element : %w", err)
 	}
 
+	if e.IsIdentity() {
+		return nil, internal.ErrIdentity
+	}
+
 	return e, nil
 }
 

group/groups.go

@@ -140,11 +140,6 @@ func (i Group) ElementLength() int {
 	return i.get().ElementLength()
 }
 
-// Identity returns the group's identity element.
-func (i Group) Identity() *Point {
-	return newPoint(i.get().Identity())
-}
-
 // HashToGroup allows arbitrary input to be safely mapped to the curve of the Group.
 func (i Group) HashToGroup(input, dst []byte) *Point {
 	return newPoint(i.get().HashToGroup(input, dst))

group/internal/element.go

@@ -29,7 +29,7 @@ type Point interface {
 	// Copy returns a copy of the point.
 	Copy() Point
 
-	// Decode decodes the input an sets the current point to its value, and returns it.
+	// Decode decodes the input a sets the current point to its value, and returns it.
 	Decode(in []byte) (Point, error)
 
 	// Bytes returns the compressed byte encoding of the point.

group/internal/errors.go

@@ -0,0 +1,13 @@
+// SPDX-License-Group: MIT
+//
+// Copyright (C) 2021 Daniel Bourdrez. All Rights Reserved.
+//
+// This source code is licensed under the MIT license found in the
+// LICENSE file in the root directory of this source tree or at
+// https://spdx.org/licenses/MIT.html
+
+package internal
+
+import "errors"
+
+var ErrIdentity = errors.New("infinity/identity point")

group/internal/group.go

@@ -28,9 +28,6 @@ type Group interface {
 	// ElementLength returns the byte size of an encoded element.
 	ElementLength() int
 
-	// Identity returns the group's identity element.
-	Identity() Point
-
 	// HashToGroup allows arbitrary input to be safely mapped to the curve of the Group.
 	HashToGroup(input, dst []byte) Point
 

group/other/encoding.go

@@ -6,11 +6,13 @@
 // LICENSE file in the root directory of this source tree or at
 // https://spdx.org/licenses/MIT.html
 
-// Package other wraps an hash-to-curve implementation and exposes functions for operations on points and scalars.
+// Package other wraps a hash-to-curve implementation and exposes functions for operations on points and scalars.
 package other
 
 import (
 	"math/big"
+
+	"github.com/bytemare/crypto/group/internal"
 )
 
 func pointLen(bitLen int) int {
@@ -90,6 +92,10 @@ func (p *Point) recoverPoint(input []byte) (*Point, error) {
 		return nil, err
 	}
 
+	if p.point.IsIdentity() {
+		return nil, internal.ErrIdentity
+	}
+
 	return p, nil
 }
 

group/ristretto/element.go

@@ -96,6 +96,11 @@ func (p *Point) Decode(in []byte) (internal.Point, error) {
 		return nil, err
 	}
 
+	// superfluous identity check
+	if el.Equal(ristretto255.NewElement().Zero()) == 1 {
+		return nil, internal.ErrIdentity
+	}
+
 	p.point = el
 
 	return p, nil