1 files changed, 143 insertions, 0 deletions

diff --git a/vendor/golang.org/x/crypto/openpgp/packet/ocfb.go b/vendor/golang.org/x/crypto/openpgp/packet/ocfb.go
new file mode 100644
index 0000000..ce2a33a
--- /dev/null
+++ b/vendor/golang.org/x/crypto/openpgp/packet/ocfb.go
@@ -0,0 +1,143 @@
+// 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 packet
+
+import (
+        "crypto/cipher"
+)
+
+type ocfbEncrypter struct {
+        b       cipher.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 cipher.Stream which encrypts data with OpenPGP's
+// cipher feedback mode using the given cipher.Block, and an initial amount of
+// ciphertext.  randData must be random bytes and be the same length as the
+// cipher.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 cipher.Block, randData []byte, resync OCFBResyncOption) (cipher.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       cipher.Block
+        fre     []byte
+        outUsed int
+}
+
+// NewOCFBDecrypter returns a cipher.Stream which decrypts data with OpenPGP's
+// cipher feedback mode using the given cipher.Block. Prefix must be the first
+// blockSize + 2 bytes of the ciphertext, where blockSize is the cipher.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 cipher.Block, prefix []byte, resync OCFBResyncOption) cipher.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++
+        }
+}