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- // Copyright (c) 2019 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.
- package edwards25519
- import (
- "testing"
- "testing/quick"
- )
- func TestScalarAliasing(t *testing.T) {
- checkAliasingOneArg := func(f func(v, x *Scalar) *Scalar, v, x Scalar) bool {
- x1, v1 := x, x
- // Calculate a reference f(x) without aliasing.
- if out := f(&v, &x); out != &v || !isReduced(out) {
- return false
- }
- // Test aliasing the argument and the receiver.
- if out := f(&v1, &v1); out != &v1 || v1 != v || !isReduced(out) {
- return false
- }
- // Ensure the arguments was not modified.
- return x == x1
- }
- checkAliasingTwoArgs := func(f func(v, x, y *Scalar) *Scalar, v, x, y Scalar) bool {
- x1, y1, v1 := x, y, Scalar{}
- // Calculate a reference f(x, y) without aliasing.
- if out := f(&v, &x, &y); out != &v || !isReduced(out) {
- return false
- }
- // Test aliasing the first argument and the receiver.
- v1 = x
- if out := f(&v1, &v1, &y); out != &v1 || v1 != v || !isReduced(out) {
- return false
- }
- // Test aliasing the second argument and the receiver.
- v1 = y
- if out := f(&v1, &x, &v1); out != &v1 || v1 != v || !isReduced(out) {
- return false
- }
- // Calculate a reference f(x, x) without aliasing.
- if out := f(&v, &x, &x); out != &v || !isReduced(out) {
- return false
- }
- // Test aliasing the first argument and the receiver.
- v1 = x
- if out := f(&v1, &v1, &x); out != &v1 || v1 != v || !isReduced(out) {
- return false
- }
- // Test aliasing the second argument and the receiver.
- v1 = x
- if out := f(&v1, &x, &v1); out != &v1 || v1 != v || !isReduced(out) {
- return false
- }
- // Test aliasing both arguments and the receiver.
- v1 = x
- if out := f(&v1, &v1, &v1); out != &v1 || v1 != v || !isReduced(out) {
- return false
- }
- // Ensure the arguments were not modified.
- return x == x1 && y == y1
- }
- for name, f := range map[string]any{
- "Negate": func(v, x Scalar) bool {
- return checkAliasingOneArg((*Scalar).Negate, v, x)
- },
- "Multiply": func(v, x, y Scalar) bool {
- return checkAliasingTwoArgs((*Scalar).Multiply, v, x, y)
- },
- "Add": func(v, x, y Scalar) bool {
- return checkAliasingTwoArgs((*Scalar).Add, v, x, y)
- },
- "Subtract": func(v, x, y Scalar) bool {
- return checkAliasingTwoArgs((*Scalar).Subtract, v, x, y)
- },
- } {
- err := quick.Check(f, &quick.Config{MaxCountScale: 1 << 5})
- if err != nil {
- t.Errorf("%v: %v", name, err)
- }
- }
- }
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