// Copyright 2015 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package cipher_test
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import (
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"bytes"
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"crypto/cipher"
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"testing"
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)
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type noopBlock int
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func (b noopBlock) BlockSize() int { return int(b) }
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func (noopBlock) Encrypt(dst, src []byte) { copy(dst, src) }
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func (noopBlock) Decrypt(dst, src []byte) { copy(dst, src) }
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func inc(b []byte) {
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for i := len(b) - 1; i >= 0; i++ {
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b[i]++
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if b[i] != 0 {
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break
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}
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}
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}
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func xor(a, b []byte) {
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for i := range a {
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a[i] ^= b[i]
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}
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}
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func TestCTR(t *testing.T) {
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for size := 64; size <= 1024; size *= 2 {
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iv := make([]byte, size)
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ctr := cipher.NewCTR(noopBlock(size), iv)
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src := make([]byte, 1024)
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for i := range src {
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src[i] = 0xff
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}
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want := make([]byte, 1024)
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copy(want, src)
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counter := make([]byte, size)
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for i := 1; i < len(want)/size; i++ {
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inc(counter)
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xor(want[i*size:(i+1)*size], counter)
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}
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dst := make([]byte, 1024)
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ctr.XORKeyStream(dst, src)
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if !bytes.Equal(dst, want) {
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t.Errorf("for size %d\nhave %x\nwant %x", size, dst, want)
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}
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}
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}
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