Imported Upstream version 60upstream/60

3 files changed, 136 insertions, 0 deletions

diff --git a/src/pkg/crypto/rc4/Makefile b/src/pkg/crypto/rc4/Makefile
new file mode 100644
index 000000000..50a3b7972
--- /dev/null
+++ b/src/pkg/crypto/rc4/Makefile
@@ -0,0 +1,11 @@
+# Copyright 2009 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.
+
+include ../../../Make.inc
+
+TARG=crypto/rc4
+GOFILES=\
+	rc4.go\
+
+include ../../../Make.pkg
diff --git a/src/pkg/crypto/rc4/rc4.go b/src/pkg/crypto/rc4/rc4.go
new file mode 100644
index 000000000..7ee471093
--- /dev/null
+++ b/src/pkg/crypto/rc4/rc4.go
@@ -0,0 +1,66 @@
+// Copyright 2009 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.
+
+// Package rc4 implements RC4 encryption, as defined in Bruce Schneier's
+// Applied Cryptography.
+package rc4
+
+// BUG(agl): RC4 is in common use but has design weaknesses that make
+// it a poor choice for new protocols.
+
+import (
+	"os"
+	"strconv"
+)
+
+// A Cipher is an instance of RC4 using a particular key.
+type Cipher struct {
+	s    [256]byte
+	i, j uint8
+}
+
+type KeySizeError int
+
+func (k KeySizeError) String() string {
+	return "crypto/rc4: invalid key size " + strconv.Itoa(int(k))
+}
+
+// NewCipher creates and returns a new Cipher.  The key argument should be the
+// RC4 key, at least 1 byte and at most 256 bytes.
+func NewCipher(key []byte) (*Cipher, os.Error) {
+	k := len(key)
+	if k < 1 || k > 256 {
+		return nil, KeySizeError(k)
+	}
+	var c Cipher
+	for i := 0; i < 256; i++ {
+		c.s[i] = uint8(i)
+	}
+	var j uint8 = 0
+	for i := 0; i < 256; i++ {
+		j += c.s[i] + key[i%k]
+		c.s[i], c.s[j] = c.s[j], c.s[i]
+	}
+	return &c, nil
+}
+
+// XORKeyStream sets dst to the result of XORing src with the key stream.
+// Dst and src may be the same slice but otherwise should not overlap.
+func (c *Cipher) XORKeyStream(dst, src []byte) {
+	for i := range src {
+		c.i += 1
+		c.j += c.s[c.i]
+		c.s[c.i], c.s[c.j] = c.s[c.j], c.s[c.i]
+		dst[i] = src[i] ^ c.s[c.s[c.i]+c.s[c.j]]
+	}
+}
+
+// Reset zeros the key data so that it will no longer appear in the
+// process's memory.
+func (c *Cipher) Reset() {
+	for i := range c.s {
+		c.s[i] = 0
+	}
+	c.i, c.j = 0, 0
+}
diff --git a/src/pkg/crypto/rc4/rc4_test.go b/src/pkg/crypto/rc4/rc4_test.go
new file mode 100644
index 000000000..6265d9408
--- /dev/null
+++ b/src/pkg/crypto/rc4/rc4_test.go
@@ -0,0 +1,59 @@
+// Copyright 2009 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.
+
+package rc4
+
+import (
+	"testing"
+)
+
+type rc4Test struct {
+	key, keystream []byte
+}
+
+var golden = []rc4Test{
+	// Test vectors from the original cypherpunk posting of ARC4:
+	//   http://groups.google.com/group/sci.crypt/msg/10a300c9d21afca0?pli=1
+	{
+		[]byte{0x01, 0x23, 0x45, 0x67, 0x89, 0xab, 0xcd, 0xef},
+		[]byte{0x74, 0x94, 0xc2, 0xe7, 0x10, 0x4b, 0x08, 0x79},
+	},
+	{
+		[]byte{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},
+		[]byte{0xde, 0x18, 0x89, 0x41, 0xa3, 0x37, 0x5d, 0x3a},
+	},
+	{
+		[]byte{0xef, 0x01, 0x23, 0x45},
+		[]byte{0xd6, 0xa1, 0x41, 0xa7, 0xec, 0x3c, 0x38, 0xdf, 0xbd, 0x61},
+	},
+
+	// Test vectors from the Wikipedia page: http://en.wikipedia.org/wiki/RC4
+	{
+		[]byte{0x4b, 0x65, 0x79},
+		[]byte{0xeb, 0x9f, 0x77, 0x81, 0xb7, 0x34, 0xca, 0x72, 0xa7, 0x19},
+	},
+	{
+		[]byte{0x57, 0x69, 0x6b, 0x69},
+		[]byte{0x60, 0x44, 0xdb, 0x6d, 0x41, 0xb7},
+	},
+}
+
+func TestGolden(t *testing.T) {
+	for i := 0; i < len(golden); i++ {
+		g := golden[i]
+		c, err := NewCipher(g.key)
+		if err != nil {
+			t.Errorf("Failed to create cipher at golden index %d", i)
+			return
+		}
+		keystream := make([]byte, len(g.keystream))
+		c.XORKeyStream(keystream, keystream)
+		for j, v := range keystream {
+			if g.keystream[j] != v {
+				t.Errorf("Failed at golden index %d", i)
+				break
+			}
+		}
+	}
+}