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// Copyright 2012 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 elliptic
import (
"math/big"
"math/bits"
"math/rand"
"reflect"
"testing"
"testing/quick"
)
var toFromBigTests = []string{
"0",
"1",
"23",
"b70e0cb46bb4bf7f321390b94a03c1d356c01122343280d6105c1d21",
"706a46d476dcb76798e6046d89474788d164c18032d268fd10704fa6",
}
func p224AlternativeToBig(in *p224FieldElement) *big.Int {
ret := new(big.Int)
tmp := new(big.Int)
for i := len(in) - 1; i >= 0; i-- {
ret.Lsh(ret, 28)
tmp.SetInt64(int64(in[i]))
ret.Add(ret, tmp)
}
ret.Mod(ret, P224().Params().P)
return ret
}
func TestP224ToFromBig(t *testing.T) {
for i, test := range toFromBigTests {
n, _ := new(big.Int).SetString(test, 16)
var x p224FieldElement
p224FromBig(&x, n)
m := p224ToBig(&x)
if n.Cmp(m) != 0 {
t.Errorf("#%d: %x != %x", i, n, m)
}
q := p224AlternativeToBig(&x)
if n.Cmp(q) != 0 {
t.Errorf("#%d: %x != %x (alternative)", i, n, q)
}
}
}
// quickCheckConfig32 will make each quickcheck test run (32 * -quickchecks)
// times. The default value of -quickchecks is 100.
var quickCheckConfig32 = &quick.Config{MaxCountScale: 32}
// weirdLimbs can be combined to generate a range of edge-case field elements.
var weirdLimbs = [...]uint32{
0, 1, (1 << 29) - 1,
(1 << 12), (1 << 12) - 1,
(1 << 28), (1 << 28) - 1,
}
func generateLimb(rand *rand.Rand) uint32 {
const bottom29Bits = 0x1fffffff
n := rand.Intn(len(weirdLimbs) + 3)
switch n {
case len(weirdLimbs):
// Random value.
return uint32(rand.Int31n(1 << 29))
case len(weirdLimbs) + 1:
// Sum of two values.
k := generateLimb(rand) + generateLimb(rand)
return k & bottom29Bits
case len(weirdLimbs) + 2:
// Difference of two values.
k := generateLimb(rand) - generateLimb(rand)
return k & bottom29Bits
default:
return weirdLimbs[n]
}
}
func (p224FieldElement) Generate(rand *rand.Rand, size int) reflect.Value {
return reflect.ValueOf(p224FieldElement{
weirdLimbs[rand.Intn(len(weirdLimbs))],
weirdLimbs[rand.Intn(len(weirdLimbs))],
weirdLimbs[rand.Intn(len(weirdLimbs))],
weirdLimbs[rand.Intn(len(weirdLimbs))],
weirdLimbs[rand.Intn(len(weirdLimbs))],
weirdLimbs[rand.Intn(len(weirdLimbs))],
weirdLimbs[rand.Intn(len(weirdLimbs))],
weirdLimbs[rand.Intn(len(weirdLimbs))],
})
}
func isInBounds(x *p224FieldElement) bool {
return bits.Len32(x[0]) <= 29 &&
bits.Len32(x[1]) <= 29 &&
bits.Len32(x[2]) <= 29 &&
bits.Len32(x[3]) <= 29 &&
bits.Len32(x[4]) <= 29 &&
bits.Len32(x[5]) <= 29 &&
bits.Len32(x[6]) <= 29 &&
bits.Len32(x[7]) <= 29
}
func TestP224Mul(t *testing.T) {
mulMatchesBigInt := func(a, b, out p224FieldElement) bool {
var tmp p224LargeFieldElement
p224Mul(&out, &a, &b, &tmp)
exp := new(big.Int).Mul(p224AlternativeToBig(&a), p224AlternativeToBig(&b))
exp.Mod(exp, P224().Params().P)
got := p224AlternativeToBig(&out)
if exp.Cmp(got) != 0 || !isInBounds(&out) {
t.Logf("a = %x", a)
t.Logf("b = %x", b)
t.Logf("p224Mul(a, b) = %x = %v", out, got)
t.Logf("a * b = %v", exp)
return false
}
return true
}
a := p224FieldElement{0xfffffff, 0xfffffff, 0xf00ffff, 0x20f, 0x0, 0x0, 0x0, 0x0}
b := p224FieldElement{1, 0, 0, 0, 0, 0, 0, 0}
if !mulMatchesBigInt(a, b, p224FieldElement{}) {
t.Fail()
}
if err := quick.Check(mulMatchesBigInt, quickCheckConfig32); err != nil {
t.Error(err)
}
}
func TestP224Square(t *testing.T) {
squareMatchesBigInt := func(a, out p224FieldElement) bool {
var tmp p224LargeFieldElement
p224Square(&out, &a, &tmp)
exp := p224AlternativeToBig(&a)
exp.Mul(exp, exp)
exp.Mod(exp, P224().Params().P)
got := p224AlternativeToBig(&out)
if exp.Cmp(got) != 0 || !isInBounds(&out) {
t.Logf("a = %x", a)
t.Logf("p224Square(a, b) = %x = %v", out, got)
t.Logf("a * a = %v", exp)
return false
}
return true
}
if err := quick.Check(squareMatchesBigInt, quickCheckConfig32); err != nil {
t.Error(err)
}
}
func TestP224Add(t *testing.T) {
addMatchesBigInt := func(a, b, out p224FieldElement) bool {
p224Add(&out, &a, &b)
exp := new(big.Int).Add(p224AlternativeToBig(&a), p224AlternativeToBig(&b))
exp.Mod(exp, P224().Params().P)
got := p224AlternativeToBig(&out)
if exp.Cmp(got) != 0 {
t.Logf("a = %x", a)
t.Logf("b = %x", b)
t.Logf("p224Add(a, b) = %x = %v", out, got)
t.Logf("a + b = %v", exp)
return false
}
return true
}
if err := quick.Check(addMatchesBigInt, quickCheckConfig32); err != nil {
t.Error(err)
}
}
func TestP224Reduce(t *testing.T) {
reduceMatchesBigInt := func(a p224FieldElement) bool {
out := a
// TODO: generate higher values for functions like p224Reduce that are
// expected to work with higher input bounds.
p224Reduce(&out)
exp := p224AlternativeToBig(&a)
got := p224AlternativeToBig(&out)
if exp.Cmp(got) != 0 || !isInBounds(&out) {
t.Logf("a = %x = %v", a, exp)
t.Logf("p224Reduce(a) = %x = %v", out, got)
return false
}
return true
}
if err := quick.Check(reduceMatchesBigInt, quickCheckConfig32); err != nil {
t.Error(err)
}
}
func TestP224Contract(t *testing.T) {
contractMatchesBigInt := func(a, out p224FieldElement) bool {
p224Contract(&out, &a)
exp := p224AlternativeToBig(&a)
got := p224AlternativeToBig(&out)
if exp.Cmp(got) != 0 {
t.Logf("a = %x = %v", a, exp)
t.Logf("p224Contract(a) = %x = %v", out, got)
return false
}
// Check that out < P.
for i := range p224P {
k := 8 - i - 1
if out[k] > p224P[k] {
t.Logf("p224Contract(a) = %x", out)
return false
}
if out[k] < p224P[k] {
return true
}
}
t.Logf("p224Contract(a) = %x", out)
return false
}
if !contractMatchesBigInt(p224P, p224FieldElement{}) {
t.Error("p224Contract(p) is broken")
}
pMinus1 := p224FieldElement{0, 0, 0, 0xffff000, 0xfffffff, 0xfffffff, 0xfffffff, 0xfffffff}
if !contractMatchesBigInt(pMinus1, p224FieldElement{}) {
t.Error("p224Contract(p - 1) is broken")
}
// Check that we can handle input above p, but lowest limb zero.
a := p224FieldElement{0, 1, 0, 0xffff000, 0xfffffff, 0xfffffff, 0xfffffff, 0xfffffff}
if !contractMatchesBigInt(a, p224FieldElement{}) {
t.Error("p224Contract(p + 2²⁸) is broken")
}
// Check that we can handle input above p, but lowest three limbs zero.
b := p224FieldElement{0, 0, 0, 0xffff001, 0xfffffff, 0xfffffff, 0xfffffff, 0xfffffff}
if !contractMatchesBigInt(b, p224FieldElement{}) {
t.Error("p224Contract(p + 2⁸⁴) is broken")
}
if err := quick.Check(contractMatchesBigInt, quickCheckConfig32); err != nil {
t.Error(err)
}
}
func TestP224IsZero(t *testing.T) {
if got := p224IsZero(&p224FieldElement{}); got != 1 {
t.Errorf("p224IsZero(0) = %d, expected 1", got)
}
if got := p224IsZero((*p224FieldElement)(&p224P)); got != 1 {
t.Errorf("p224IsZero(p) = %d, expected 1", got)
}
if got := p224IsZero(&p224FieldElement{1}); got != 0 {
t.Errorf("p224IsZero(1) = %d, expected 0", got)
}
isZeroMatchesBigInt := func(a p224FieldElement) bool {
isZero := p224IsZero(&a)
big := p224AlternativeToBig(&a)
if big.Sign() == 0 && isZero != 1 {
return false
}
if big.Sign() != 0 && isZero != 0 {
return false
}
return true
}
if err := quick.Check(isZeroMatchesBigInt, quickCheckConfig32); err != nil {
t.Error(err)
}
}
func TestP224Invert(t *testing.T) {
var out p224FieldElement
p224Invert(&out, &p224FieldElement{})
if got := p224IsZero(&out); got != 1 {
t.Errorf("p224Invert(0) = %x, expected 0", out)
}
p224Invert(&out, (*p224FieldElement)(&p224P))
if got := p224IsZero(&out); got != 1 {
t.Errorf("p224Invert(p) = %x, expected 0", out)
}
p224Invert(&out, &p224FieldElement{1})
p224Contract(&out, &out)
if out != (p224FieldElement{1}) {
t.Errorf("p224Invert(1) = %x, expected 1", out)
}
var tmp p224LargeFieldElement
a := p224FieldElement{1, 2, 3, 4, 5, 6, 7, 8}
p224Invert(&out, &a)
p224Mul(&out, &out, &a, &tmp)
p224Contract(&out, &out)
if out != (p224FieldElement{1}) {
t.Errorf("p224Invert(a) * a = %x, expected 1", out)
}
}