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// Copyright 2009 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 block
import (
"bytes"
"fmt"
"io"
"testing"
"testing/iotest"
)
// Simple Cipher for testing: adds an incrementing amount
// to each byte in each
type IncCipher struct {
blockSize int
delta byte
encrypting bool
}
func (c *IncCipher) BlockSize() int { return c.blockSize }
func (c *IncCipher) Encrypt(dst, src []byte) {
if !c.encrypting {
panic("encrypt: not encrypting")
}
if len(src) != c.blockSize || len(dst) != c.blockSize {
panic(fmt.Sprintln("encrypt: wrong block size", c.blockSize, len(src), len(dst)))
}
c.delta++
for i, b := range src {
dst[i] = b + c.delta
}
}
func (c *IncCipher) Decrypt(dst, src []byte) {
if c.encrypting {
panic("decrypt: not decrypting")
}
if len(src) != c.blockSize || len(dst) != c.blockSize {
panic(fmt.Sprintln("decrypt: wrong block size ", c.blockSize, " ", len(src), " ", len(dst)))
}
c.delta--
for i, b := range src {
dst[i] = b + c.delta
}
}
func TestECBEncrypter(t *testing.T) {
var plain, crypt [256]byte
for i := 0; i < len(plain); i++ {
plain[i] = byte(i)
}
b := new(bytes.Buffer)
for block := 1; block <= 64; block *= 2 {
// compute encrypted version
delta := byte(0)
for i := 0; i < len(crypt); i++ {
if i%block == 0 {
delta++
}
crypt[i] = plain[i] + delta
}
for frag := 0; frag < 2; frag++ {
c := &IncCipher{block, 0, true}
b.Reset()
r := bytes.NewBuffer(plain[0:])
w := NewECBEncrypter(c, b)
// copy plain into w in increasingly large chunks: 1, 1, 2, 4, 8, ...
// if frag != 0, move the 1 to the end to cause fragmentation.
if frag == 0 {
_, err := io.Copyn(w, r, 1)
if err != nil {
t.Errorf("block=%d frag=0: first Copyn: %s", block, err)
continue
}
}
for n := 1; n <= len(plain)/2; n *= 2 {
_, err := io.Copyn(w, r, int64(n))
if err != nil {
t.Errorf("block=%d frag=%d: Copyn %d: %s", block, frag, n, err)
}
}
if frag != 0 {
_, err := io.Copyn(w, r, 1)
if err != nil {
t.Errorf("block=%d frag=1: last Copyn: %s", block, err)
continue
}
}
// check output
data := b.Bytes()
if len(data) != len(crypt) {
t.Errorf("block=%d frag=%d: want %d bytes, got %d", block, frag, len(crypt), len(data))
continue
}
if string(data) != string(crypt[0:]) {
t.Errorf("block=%d frag=%d: want %x got %x", block, frag, data, crypt)
}
}
}
}
func testECBDecrypter(t *testing.T, maxio int) {
var readers = []func(io.Reader) io.Reader{
func(r io.Reader) io.Reader { return r },
iotest.OneByteReader,
iotest.HalfReader,
}
var plain, crypt [256]byte
for i := 0; i < len(plain); i++ {
plain[i] = byte(255 - i)
}
b := new(bytes.Buffer)
for block := 1; block <= 64 && block <= maxio; block *= 2 {
// compute encrypted version
delta := byte(0)
for i := 0; i < len(crypt); i++ {
if i%block == 0 {
delta++
}
crypt[i] = plain[i] + delta
}
for mode := 0; mode < len(readers); mode++ {
for frag := 0; frag < 2; frag++ {
test := fmt.Sprintf("block=%d mode=%d frag=%d maxio=%d", block, mode, frag, maxio)
c := &IncCipher{block, 0, false}
b.Reset()
r := NewECBDecrypter(c, readers[mode](bytes.NewBuffer(crypt[0:maxio])))
// read from crypt in increasingly large chunks: 1, 1, 2, 4, 8, ...
// if frag == 1, move the 1 to the end to cause fragmentation.
if frag == 0 {
_, err := io.Copyn(b, r, 1)
if err != nil {
t.Errorf("%s: first Copyn: %s", test, err)
continue
}
}
for n := 1; n <= maxio/2; n *= 2 {
_, err := io.Copyn(b, r, int64(n))
if err != nil {
t.Errorf("%s: Copyn %d: %s", test, n, err)
}
}
if frag != 0 {
_, err := io.Copyn(b, r, 1)
if err != nil {
t.Errorf("%s: last Copyn: %s", test, err)
continue
}
}
// check output
data := b.Bytes()
if len(data) != maxio {
t.Errorf("%s: want %d bytes, got %d", test, maxio, len(data))
continue
}
if string(data) != string(plain[0:maxio]) {
t.Errorf("%s: input=%x want %x got %x", test, crypt[0:maxio], plain[0:maxio], data)
}
}
}
}
}
func TestECBDecrypter(t *testing.T) {
// Do shorter I/O sizes first; they're easier to debug.
for n := 1; n <= 256 && !t.Failed(); n *= 2 {
testECBDecrypter(t, n)
}
}
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