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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 curve25519_test
import (
"bytes"
"crypto/rand"
"encoding/hex"
"testing"
"golang.org/x/crypto/curve25519"
)
const expectedHex = "89161fde887b2b53de549af483940106ecc114d6982daa98256de23bdf77661a"
func TestX25519Basepoint(t *testing.T) {
x := make([]byte, 32)
x[0] = 1
for i := 0; i < 200; i++ {
var err error
x, err = curve25519.X25519(x, curve25519.Basepoint)
if err != nil {
t.Fatal(err)
}
}
result := hex.EncodeToString(x)
if result != expectedHex {
t.Errorf("incorrect result: got %s, want %s", result, expectedHex)
}
}
func TestLowOrderPoints(t *testing.T) {
scalar := make([]byte, curve25519.ScalarSize)
if _, err := rand.Read(scalar); err != nil {
t.Fatal(err)
}
for i, p := range lowOrderPoints {
out, err := curve25519.X25519(scalar, p)
if err == nil {
t.Errorf("%d: expected error, got nil", i)
}
if out != nil {
t.Errorf("%d: expected nil output, got %x", i, out)
}
}
}
func TestTestVectors(t *testing.T) {
t.Run("Legacy", func(t *testing.T) { testTestVectors(t, curve25519.ScalarMult) })
t.Run("X25519", func(t *testing.T) {
testTestVectors(t, func(dst, scalar, point *[32]byte) {
out, err := curve25519.X25519(scalar[:], point[:])
if err != nil {
t.Fatal(err)
}
copy(dst[:], out)
})
})
}
func testTestVectors(t *testing.T, scalarMult func(dst, scalar, point *[32]byte)) {
for _, tv := range testVectors {
var got [32]byte
scalarMult(&got, &tv.In, &tv.Base)
if !bytes.Equal(got[:], tv.Expect[:]) {
t.Logf(" in = %x", tv.In)
t.Logf(" base = %x", tv.Base)
t.Logf(" got = %x", got)
t.Logf("expect = %x", tv.Expect)
t.Fail()
}
}
}
// TestHighBitIgnored tests the following requirement in RFC 7748:
//
// When receiving such an array, implementations of X25519 (but not X448) MUST
// mask the most significant bit in the final byte.
//
// Regression test for issue #30095.
func TestHighBitIgnored(t *testing.T) {
var s, u [32]byte
rand.Read(s[:])
rand.Read(u[:])
var hi0, hi1 [32]byte
u[31] &= 0x7f
curve25519.ScalarMult(&hi0, &s, &u)
u[31] |= 0x80
curve25519.ScalarMult(&hi1, &s, &u)
if !bytes.Equal(hi0[:], hi1[:]) {
t.Errorf("high bit of group point should not affect result")
}
}
var benchmarkSink byte
func BenchmarkX25519Basepoint(b *testing.B) {
scalar := make([]byte, curve25519.ScalarSize)
if _, err := rand.Read(scalar); err != nil {
b.Fatal(err)
}
b.ResetTimer()
for i := 0; i < b.N; i++ {
out, err := curve25519.X25519(scalar, curve25519.Basepoint)
if err != nil {
b.Fatal(err)
}
benchmarkSink ^= out[0]
}
}
func BenchmarkX25519(b *testing.B) {
scalar := make([]byte, curve25519.ScalarSize)
if _, err := rand.Read(scalar); err != nil {
b.Fatal(err)
}
point, err := curve25519.X25519(scalar, curve25519.Basepoint)
if err != nil {
b.Fatal(err)
}
if _, err := rand.Read(scalar); err != nil {
b.Fatal(err)
}
b.ResetTimer()
for i := 0; i < b.N; i++ {
out, err := curve25519.X25519(scalar, point)
if err != nil {
b.Fatal(err)
}
benchmarkSink ^= out[0]
}
}
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