Gecko [ 167.86.127.34 ]

Name	Size	Permission
benchmark_test.go	3.46 KB	-rw-r--r--
cbc.go	4.42 KB	-rw-r--r--
cbc_aes_test.go	2.93 KB	-rw-r--r--
cfb.go	1.94 KB	-rw-r--r--
cfb_test.go	2.77 KB	-rw-r--r--
cipher.go	2.49 KB	-rw-r--r--
cipher_test.go	2.2 KB	-rw-r--r--
common_test.go	1.24 KB	-rw-r--r--
ctr.go	2.12 KB	-rw-r--r--
ctr_aes_test.go	2.98 KB	-rw-r--r--
ctr_test.go	1.13 KB	-rw-r--r--
example_test.go	11.78 KB	-rw-r--r--
export_test.go	242 B	-rw-r--r--
gcm.go	13.82 KB	-rw-r--r--
gcm_test.go	21.3 KB	-rw-r--r--
io.go	1.46 KB	-rw-r--r--
ofb.go	1.6 KB	-rw-r--r--
ofb_test.go	2.95 KB	-rw-r--r--
xor_amd64.go	642 B	-rw-r--r--
xor_amd64.s	1.31 KB	-rw-r--r--
xor_generic.go	2.33 KB	-rw-r--r--
xor_ppc64x.go	641 B	-rw-r--r--
xor_ppc64x.s	2.03 KB	-rw-r--r--
xor_test.go	1.6 KB	-rw-r--r--

Code Editor : ofb.go

// Copyright 2011 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.

// OFB (Output Feedback) Mode.

package cipher

import "crypto/internal/subtle"

type ofb struct {
	b       Block
	cipher  []byte
	out     []byte
	outUsed int
}

// NewOFB returns a Stream that encrypts or decrypts using the block cipher b
// in output feedback mode. The initialization vector iv's length must be equal
// to b's block size.
func NewOFB(b Block, iv []byte) Stream {
	blockSize := b.BlockSize()
	if len(iv) != blockSize {
		panic("cipher.NewOFB: IV length must equal block size")
	}
	bufSize := streamBufferSize
	if bufSize < blockSize {
		bufSize = blockSize
	}
	x := &ofb{
		b:       b,
		cipher:  make([]byte, blockSize),
		out:     make([]byte, 0, bufSize),
		outUsed: 0,
	}

copy(x.cipher, iv)
	return x
}

func (x *ofb) refill() {
	bs := x.b.BlockSize()
	remain := len(x.out) - x.outUsed
	if remain > x.outUsed {
		return
	}
	copy(x.out, x.out[x.outUsed:])
	x.out = x.out[:cap(x.out)]
	for remain < len(x.out)-bs {
		x.b.Encrypt(x.cipher, x.cipher)
		copy(x.out[remain:], x.cipher)
		remain += bs
	}
	x.out = x.out[:remain]
	x.outUsed = 0
}

func (x *ofb) XORKeyStream(dst, src []byte) {
	if len(dst) < len(src) {
		panic("crypto/cipher: output smaller than input")
	}
	if subtle.InexactOverlap(dst[:len(src)], src) {
		panic("crypto/cipher: invalid buffer overlap")
	}
	for len(src) > 0 {
		if x.outUsed >= len(x.out)-x.b.BlockSize() {
			x.refill()
		}
		n := xorBytes(dst, src, x.out[x.outUsed:])
		dst = dst[n:]
		src = src[n:]
		x.outUsed += n
	}
}

${this.title}

Code Editor : ofb.go