From 554fd8c5195424bdbcabf5de30fdc183aba391bd Mon Sep 17 00:00:00 2001
From: upstream source tree <ports@midipix.org>
Date: Sun, 15 Mar 2015 20:14:05 -0400
Subject: obtained gcc-4.6.4.tar.bz2 from upstream website; verified
 gcc-4.6.4.tar.bz2.sig; imported gcc-4.6.4 source tree from verified upstream
 tarball.

downloading a git-generated archive based on the 'upstream' tag
should provide you with a source tree that is binary identical
to the one extracted from the above tarball.

if you have obtained the source via the command 'git clone',
however, do note that line-endings of files in your working
directory might differ from line-endings of the respective
files in the upstream repository.
---
 libgo/go/crypto/cipher/ofb.go | 44 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)
 create mode 100644 libgo/go/crypto/cipher/ofb.go

(limited to 'libgo/go/crypto/cipher/ofb.go')

diff --git a/libgo/go/crypto/cipher/ofb.go b/libgo/go/crypto/cipher/ofb.go
new file mode 100644
index 000000000..85e5f02b0
--- /dev/null
+++ b/libgo/go/crypto/cipher/ofb.go
@@ -0,0 +1,44 @@
+// 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
+
+type ofb struct {
+	b       Block
+	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 {
+		return nil
+	}
+
+	x := &ofb{
+		b:       b,
+		out:     make([]byte, blockSize),
+		outUsed: 0,
+	}
+	b.Encrypt(x.out, iv)
+
+	return x
+}
+
+func (x *ofb) XORKeyStream(dst, src []byte) {
+	for i, s := range src {
+		if x.outUsed == len(x.out) {
+			x.b.Encrypt(x.out, x.out)
+			x.outUsed = 0
+		}
+
+		dst[i] = s ^ x.out[x.outUsed]
+		x.outUsed++
+	}
+}
-- 
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