code review 5629044: crypto/...: changes to address some of bug 2841.

src/pkg/crypto/cipher/ocfb.go

Index: src/pkg/crypto/cipher/ocfb.go
===================================================================
deleted file mode 100644
--- a/src/pkg/crypto/cipher/ocfb.go
+++ /dev/null
@@ -1,138 +0,0 @@
-// Copyright 2010 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.
-
-// OpenPGP CFB Mode. http://tools.ietf.org/html/rfc4880#section-13.9
-
-package cipher
-
-type ocfbEncrypter struct {
-	b       Block
-	fre     []byte
-	outUsed int
-}
-
-// An OCFBResyncOption determines if the "resynchronization step" of OCFB is
-// performed.
-type OCFBResyncOption bool
-
-const (
-	OCFBResync   OCFBResyncOption = true
-	OCFBNoResync OCFBResyncOption = false
-)
-
-// NewOCFBEncrypter returns a Stream which encrypts data with OpenPGP's cipher
-// feedback mode using the given Block, and an initial amount of ciphertext.
-// randData must be random bytes and be the same length as the Block's block
-// size. Resync determines if the "resynchronization step" from RFC 4880, 13.9
-// step 7 is performed. Different parts of OpenPGP vary on this point.
-func NewOCFBEncrypter(block Block, randData []byte, resync OCFBResyncOption) (Stream, []byte) {
-	blockSize := block.BlockSize()
-	if len(randData) != blockSize {
-		return nil, nil
-	}
-
-	x := &ocfbEncrypter{
-		b:       block,
-		fre:     make([]byte, blockSize),
-		outUsed: 0,
-	}
-	prefix := make([]byte, blockSize+2)
-
-	block.Encrypt(x.fre, x.fre)
-	for i := 0; i < blockSize; i++ {
-		prefix[i] = randData[i] ^ x.fre[i]
-	}
-
-	block.Encrypt(x.fre, prefix[:blockSize])
-	prefix[blockSize] = x.fre[0] ^ randData[blockSize-2]
-	prefix[blockSize+1] = x.fre[1] ^ randData[blockSize-1]
-
-	if resync {
-		block.Encrypt(x.fre, prefix[2:])
-	} else {
-		x.fre[0] = prefix[blockSize]
-		x.fre[1] = prefix[blockSize+1]
-		x.outUsed = 2
-	}
-	return x, prefix
-}
-
-func (x *ocfbEncrypter) XORKeyStream(dst, src []byte) {
-	for i := 0; i < len(src); i++ {
-		if x.outUsed == len(x.fre) {
-			x.b.Encrypt(x.fre, x.fre)
-			x.outUsed = 0
-		}
-
-		x.fre[x.outUsed] ^= src[i]
-		dst[i] = x.fre[x.outUsed]
-		x.outUsed++
-	}
-}
-
-type ocfbDecrypter struct {
-	b       Block
-	fre     []byte
-	outUsed int
-}
-
-// NewOCFBDecrypter returns a Stream which decrypts data with OpenPGP's cipher
-// feedback mode using the given Block. Prefix must be the first blockSize + 2
-// bytes of the ciphertext, where blockSize is the Block's block size. If an
-// incorrect key is detected then nil is returned. On successful exit,
-// blockSize+2 bytes of decrypted data are written into prefix. Resync
-// determines if the "resynchronization step" from RFC 4880, 13.9 step 7 is
-// performed. Different parts of OpenPGP vary on this point.
-func NewOCFBDecrypter(block Block, prefix []byte, resync OCFBResyncOption) Stream {
-	blockSize := block.BlockSize()
-	if len(prefix) != blockSize+2 {
-		return nil
-	}
-
-	x := &ocfbDecrypter{
-		b:       block,
-		fre:     make([]byte, blockSize),
-		outUsed: 0,
-	}
-	prefixCopy := make([]byte, len(prefix))
-	copy(prefixCopy, prefix)
-
-	block.Encrypt(x.fre, x.fre)
-	for i := 0; i < blockSize; i++ {
-		prefixCopy[i] ^= x.fre[i]
-	}
-
-	block.Encrypt(x.fre, prefix[:blockSize])
-	prefixCopy[blockSize] ^= x.fre[0]
-	prefixCopy[blockSize+1] ^= x.fre[1]
-
-	if prefixCopy[blockSize-2] != prefixCopy[blockSize] ||
-		prefixCopy[blockSize-1] != prefixCopy[blockSize+1] {
-		return nil
-	}
-
-	if resync {
-		block.Encrypt(x.fre, prefix[2:])
-	} else {
-		x.fre[0] = prefix[blockSize]
-		x.fre[1] = prefix[blockSize+1]
-		x.outUsed = 2
-	}
-	copy(prefix, prefixCopy)
-	return x
-}
-
-func (x *ocfbDecrypter) XORKeyStream(dst, src []byte) {
-	for i := 0; i < len(src); i++ {
-		if x.outUsed == len(x.fre) {
-			x.b.Encrypt(x.fre, x.fre)
-			x.outUsed = 0
-		}
-
-		c := src[i]
-		dst[i] = x.fre[x.outUsed] ^ src[i]
-		x.fre[x.outUsed] = c
-		x.outUsed++
-	}
-}