if err != nil {
			t.Fatal(err)
		}

		block, err := aes.NewCipher(key)
		if err != nil {
			t.Fatal(err)
		}

		ciphertext := make([]byte, len(plaintext))
		cfb := cipher.NewCFBEncrypter(block, iv)
		cfb.XORKeyStream(ciphertext, plaintext)

		if !bytes.Equal(ciphertext, expected) {
			t.Errorf("#%d: wrong output: got %x, expected %x", i, ciphertext, expected)
		}

		if !x.decrypt {
			copy(x.next[x.outUsed:], dst)
		}
		dst = dst[n:]
		src = src[n:]
		x.outUsed += n
	}
}

// NewCFBEncrypter returns a [Stream] which encrypts with cipher feedback mode,
// using the given [Block]. The iv must be the same length as the [Block]'s block
// size.
func NewCFBEncrypter(block Block, iv []byte) Stream {
	return newCFB(block, iv, false)
}

	testBlock(t, "CTR", cipher.NewCTR)
}
func TestOFBOutOfBoundsWrite(t *testing.T) {
	testBlock(t, "OFB", cipher.NewOFB)
}
func TestCFBEncryptOutOfBoundsWrite(t *testing.T) {
	testBlock(t, "CFB Encrypt", cipher.NewCFBEncrypter)
}
func TestCFBDecryptOutOfBoundsWrite(t *testing.T) {
	testBlock(t, "CFB Decrypt", cipher.NewCFBDecrypter)
}
func testBlock(t *testing.T, name string, newCipher func(cipher.Block, []byte) cipher.Stream) {

		cbce.CryptBlocks(ct, pt[:0])
		assertEqual("CBC encrypt", ct, pt)

		cbcd := cipher.NewCBCDecrypter(b, iv)
		cbcd.CryptBlocks(ct, pt[:0])
		assertEqual("CBC decrypt", ct, pt)

		cfbe := cipher.NewCFBEncrypter(b, iv)
		cfbe.XORKeyStream(ct, pt[:0])
		assertEqual("CFB encrypt", ct, pt)

		cfbd := cipher.NewCFBDecrypter(b, iv)
		cfbd.XORKeyStream(ct, pt[:0])
		assertEqual("CFB decrypt", ct, pt)

// always be wordsize aligned, whereas non-aligned is a more typical
// use-case.
const almost1K = 1024 - 5
const almost8K = 8*1024 - 5

func BenchmarkAESCFBEncrypt1K(b *testing.B) {
	benchmarkAESStream(b, cipher.NewCFBEncrypter, make([]byte, almost1K))
}

func BenchmarkAESCFBDecrypt1K(b *testing.B) {
	benchmarkAESStream(b, cipher.NewCFBDecrypter, make([]byte, almost1K))
}

func BenchmarkAESCFBDecrypt8K(b *testing.B) {

	ciphertext := make([]byte, aes.BlockSize+len(plaintext))
	iv := ciphertext[:aes.BlockSize]
	if _, err := io.ReadFull(rand.Reader, iv); err != nil {
		panic(err)
	}

	stream := cipher.NewCFBEncrypter(block, iv)
	stream.XORKeyStream(ciphertext[aes.BlockSize:], plaintext)

	// It's important to remember that ciphertexts must be authenticated
	// (i.e. by using crypto/hmac) as well as being encrypted in order to

		{"AEAD", Type, 2},
		{"Block", Type, 0},
		{"BlockMode", Type, 0},
		{"NewCBCDecrypter", Func, 0},
		{"NewCBCEncrypter", Func, 0},
		{"NewCFBDecrypter", Func, 0},
		{"NewCFBEncrypter", Func, 0},
		{"NewCTR", Func, 0},
		{"NewGCM", Func, 2},
		{"NewGCMWithNonceSize", Func, 5},
		{"NewGCMWithTagSize", Func, 11},
		{"NewOFB", Func, 0},
		{"Stream", Type, 0},
		{"StreamReader", Type, 0},

pkg crypto/cipher, func NewCBCDecrypter(Block, []uint8) BlockMode
pkg crypto/cipher, func NewCBCEncrypter(Block, []uint8) BlockMode
pkg crypto/cipher, func NewCFBDecrypter(Block, []uint8) Stream
pkg crypto/cipher, func NewCFBEncrypter(Block, []uint8) Stream
pkg crypto/cipher, func NewCTR(Block, []uint8) Stream
pkg crypto/cipher, func NewOFB(Block, []uint8) Stream
pkg crypto/cipher, method (StreamReader) Read([]uint8) (int, error)