1// Copyright (c) 2019 The Go Authors. All rights reserved. 2// Use of this source code is governed by a BSD-style 3// license that can be found in the LICENSE file. 4 5package edwards25519 6 7import ( 8 "testing" 9 "testing/quick" 10) 11 12func TestScalarAliasing(t *testing.T) { 13 checkAliasingOneArg := func(f func(v, x *Scalar) *Scalar, v, x Scalar) bool { 14 x1, v1 := x, x 15 16 // Calculate a reference f(x) without aliasing. 17 if out := f(&v, &x); out != &v || !isReduced(out.Bytes()) { 18 return false 19 } 20 21 // Test aliasing the argument and the receiver. 22 if out := f(&v1, &v1); out != &v1 || v1 != v || !isReduced(out.Bytes()) { 23 return false 24 } 25 26 // Ensure the arguments was not modified. 27 return x == x1 28 } 29 30 checkAliasingTwoArgs := func(f func(v, x, y *Scalar) *Scalar, v, x, y Scalar) bool { 31 x1, y1, v1 := x, y, Scalar{} 32 33 // Calculate a reference f(x, y) without aliasing. 34 if out := f(&v, &x, &y); out != &v || !isReduced(out.Bytes()) { 35 return false 36 } 37 38 // Test aliasing the first argument and the receiver. 39 v1 = x 40 if out := f(&v1, &v1, &y); out != &v1 || v1 != v || !isReduced(out.Bytes()) { 41 return false 42 } 43 // Test aliasing the second argument and the receiver. 44 v1 = y 45 if out := f(&v1, &x, &v1); out != &v1 || v1 != v || !isReduced(out.Bytes()) { 46 return false 47 } 48 49 // Calculate a reference f(x, x) without aliasing. 50 if out := f(&v, &x, &x); out != &v || !isReduced(out.Bytes()) { 51 return false 52 } 53 54 // Test aliasing the first argument and the receiver. 55 v1 = x 56 if out := f(&v1, &v1, &x); out != &v1 || v1 != v || !isReduced(out.Bytes()) { 57 return false 58 } 59 // Test aliasing the second argument and the receiver. 60 v1 = x 61 if out := f(&v1, &x, &v1); out != &v1 || v1 != v || !isReduced(out.Bytes()) { 62 return false 63 } 64 // Test aliasing both arguments and the receiver. 65 v1 = x 66 if out := f(&v1, &v1, &v1); out != &v1 || v1 != v || !isReduced(out.Bytes()) { 67 return false 68 } 69 70 // Ensure the arguments were not modified. 71 return x == x1 && y == y1 72 } 73 74 for name, f := range map[string]interface{}{ 75 "Negate": func(v, x Scalar) bool { 76 return checkAliasingOneArg((*Scalar).Negate, v, x) 77 }, 78 "Multiply": func(v, x, y Scalar) bool { 79 return checkAliasingTwoArgs((*Scalar).Multiply, v, x, y) 80 }, 81 "Add": func(v, x, y Scalar) bool { 82 return checkAliasingTwoArgs((*Scalar).Add, v, x, y) 83 }, 84 "Subtract": func(v, x, y Scalar) bool { 85 return checkAliasingTwoArgs((*Scalar).Subtract, v, x, y) 86 }, 87 "MultiplyAdd1": func(v, x, y, fixed Scalar) bool { 88 return checkAliasingTwoArgs(func(v, x, y *Scalar) *Scalar { 89 return v.MultiplyAdd(&fixed, x, y) 90 }, v, x, y) 91 }, 92 "MultiplyAdd2": func(v, x, y, fixed Scalar) bool { 93 return checkAliasingTwoArgs(func(v, x, y *Scalar) *Scalar { 94 return v.MultiplyAdd(x, &fixed, y) 95 }, v, x, y) 96 }, 97 "MultiplyAdd3": func(v, x, y, fixed Scalar) bool { 98 return checkAliasingTwoArgs(func(v, x, y *Scalar) *Scalar { 99 return v.MultiplyAdd(x, y, &fixed) 100 }, v, x, y) 101 }, 102 } { 103 err := quick.Check(f, quickCheckConfig(32)) 104 if err != nil { 105 t.Errorf("%v: %v", name, err) 106 } 107 } 108} 109