// Copyright 2015 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 cipher_test import ( "bytes" "crypto/cipher" "testing" ) type noopBlock int func (b noopBlock) BlockSize() int { return int(b) } func (noopBlock) Encrypt(dst, src []byte) { copy(dst, src) } func (noopBlock) Decrypt(dst, src []byte) { copy(dst, src) } func inc(b []byte) { for i := len(b) - 1; i >= 0; i++ { b[i]++ if b[i] != 0 { break } } } func xor(a, b []byte) { for i := range a { a[i] ^= b[i] } } func TestCTR(t *testing.T) { for size := 64; size <= 1024; size *= 2 { iv := make([]byte, size) ctr := cipher.NewCTR(noopBlock(size), iv) src := make([]byte, 1024) for i := range src { src[i] = 0xff } want := make([]byte, 1024) copy(want, src) counter := make([]byte, size) for i := 1; i < len(want)/size; i++ { inc(counter) xor(want[i*size:(i+1)*size], counter) } dst := make([]byte, 1024) ctr.XORKeyStream(dst, src) if !bytes.Equal(dst, want) { t.Errorf("for size %d\nhave %x\nwant %x", size, dst, want) } } }