ff5f50c52c
Update to current version of Go library. Update testsuite for removed types. * go-lang.c (go_langhook_init): Omit float_type_size when calling go_create_gogo. * go-c.h: Update declaration of go_create_gogo. From-SVN: r169098
65 lines
1.4 KiB
Go
65 lines
1.4 KiB
Go
// Copyright 2010 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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// CFB (Cipher Feedback) Mode.
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package cipher
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type cfb struct {
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b Block
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out []byte
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outUsed int
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decrypt bool
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}
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// NewCFBEncrypter returns a Stream which encrypts with cipher feedback mode,
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// using the given Block. The iv must be the same length as the Block's block
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// size.
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func NewCFBEncrypter(block Block, iv []byte) Stream {
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return newCFB(block, iv, false)
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}
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// NewCFBDecrypter returns a Stream which decrypts with cipher feedback mode,
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// using the given Block. The iv must be the same length as the Block's block
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// size.
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func NewCFBDecrypter(block Block, iv []byte) Stream {
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return newCFB(block, iv, true)
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}
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func newCFB(block Block, iv []byte, decrypt bool) Stream {
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blockSize := block.BlockSize()
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if len(iv) != blockSize {
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return nil
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}
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x := &cfb{
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b: block,
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out: make([]byte, blockSize),
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outUsed: 0,
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decrypt: decrypt,
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}
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block.Encrypt(x.out, iv)
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return x
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}
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func (x *cfb) XORKeyStream(dst, src []byte) {
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for i := 0; i < len(src); i++ {
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if x.outUsed == len(x.out) {
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x.b.Encrypt(x.out, x.out)
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x.outUsed = 0
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}
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if x.decrypt {
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t := src[i]
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dst[i] = src[i] ^ x.out[x.outUsed]
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x.out[x.outUsed] = t
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} else {
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x.out[x.outUsed] ^= src[i]
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dst[i] = x.out[x.outUsed]
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}
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x.outUsed++
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}
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}
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