crypto: add twofish package

The code was (as annotated in the source code) adopted from Tom's
LibCrypt (public domain code, [1]). It was neither optimised for speed
nor were any security features added.

[1] http://libtom.org/?page=features&newsitems=5&whatfile=crypt

R=rsc, berengarlehr, albert.strasheim, agl1
CC=golang-dev, schulze
https://golang.org/cl/2687042

CONTRIBUTORS

@@ -68,6 +68,7 @@ Corey Thomasson <cthom.lists@gmail.com>
 Dan Sinclair <dan.sinclair@gmail.com>
 Daniel Fleischman <danielfleischman@gmail.com>
 Daniel Nadasi <dnadasi@google.com>
+Berengar Lehr <Berengar.Lehr@gmx.de>
 Daniel Theophanes <kardianos@gmail.com>
 David G. Andersen <dave.andersen@gmail.com>
 David Symonds <dsymonds@golang.org>

src/pkg/Makefile

@@ -47,6 +47,7 @@ DIRS=\
 	crypto/sha512\
 	crypto/subtle\
 	crypto/tls\
+	crypto/twofish\
 	crypto/x509\
 	crypto/xtea\
 	debug/dwarf\

src/pkg/crypto/twofish/Makefile

+# 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.
+
+include ../../../Make.inc
+
+TARG=crypto/twofish
+GOFILES=\
+	twofish.go\
+
+include ../../../Make.pkg

src/pkg/crypto/twofish/twofish_test.go

+// 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.
+
+package twofish
+
+import (
+	"bytes"
+	"testing"
+)
+
+var qbox = [2][4][16]byte{
+	{
+		{0x8, 0x1, 0x7, 0xD, 0x6, 0xF, 0x3, 0x2, 0x0, 0xB, 0x5, 0x9, 0xE, 0xC, 0xA, 0x4},
+		{0xE, 0xC, 0xB, 0x8, 0x1, 0x2, 0x3, 0x5, 0xF, 0x4, 0xA, 0x6, 0x7, 0x0, 0x9, 0xD},
+		{0xB, 0xA, 0x5, 0xE, 0x6, 0xD, 0x9, 0x0, 0xC, 0x8, 0xF, 0x3, 0x2, 0x4, 0x7, 0x1},
+		{0xD, 0x7, 0xF, 0x4, 0x1, 0x2, 0x6, 0xE, 0x9, 0xB, 0x3, 0x0, 0x8, 0x5, 0xC, 0xA},
+	},
+	{
+		{0x2, 0x8, 0xB, 0xD, 0xF, 0x7, 0x6, 0xE, 0x3, 0x1, 0x9, 0x4, 0x0, 0xA, 0xC, 0x5},
+		{0x1, 0xE, 0x2, 0xB, 0x4, 0xC, 0x3, 0x7, 0x6, 0xD, 0xA, 0x5, 0xF, 0x9, 0x0, 0x8},
+		{0x4, 0xC, 0x7, 0x5, 0x1, 0x6, 0x9, 0xA, 0x0, 0xE, 0xD, 0x8, 0x2, 0xB, 0x3, 0xF},
+		{0xB, 0x9, 0x5, 0x1, 0xC, 0x3, 0xD, 0xE, 0x6, 0x4, 0x7, 0xF, 0x2, 0x0, 0x8, 0xA},
+	},
+}
+
+// genSbox generates the variable sbox
+func genSbox(qi int, x byte) byte {
+	a0, b0 := x/16, x%16
+	for i := 0; i < 2; i++ {
+		a1 := a0 ^ b0
+		b1 := (a0 ^ ((b0 << 3) | (b0 >> 1)) ^ (a0 << 3)) & 15
+		a0 = qbox[qi][2*i][a1]
+		b0 = qbox[qi][2*i+1][b1]
+	}
+	return (b0 << 4) + a0
+}
+
+func TestSbox(t *testing.T) {
+	for n := 0; n < 2; n++ {
+		for m := 0; m < 256; m++ {
+			if genSbox(n, byte(m)) != sbox[n][m] {
+				t.Errorf("#%d|%d: sbox value = %d want %d", n, m, sbox[n][m], genSbox(n, byte(m)))
+			}
+		}
+	}
+}
+
+var testVectors = []struct {
+	key []byte
+	dec []byte
+	enc []byte
+}{
+	// These tests are extracted from LibTom
+	{
+		[]byte{0x9F, 0x58, 0x9F, 0x5C, 0xF6, 0x12, 0x2C, 0x32, 0xB6, 0xBF, 0xEC, 0x2F, 0x2A, 0xE8, 0xC3, 0x5A},
+		[]byte{0xD4, 0x91, 0xDB, 0x16, 0xE7, 0xB1, 0xC3, 0x9E, 0x86, 0xCB, 0x08, 0x6B, 0x78, 0x9F, 0x54, 0x19},
+		[]byte{0x01, 0x9F, 0x98, 0x09, 0xDE, 0x17, 0x11, 0x85, 0x8F, 0xAA, 0xC3, 0xA3, 0xBA, 0x20, 0xFB, 0xC3},
+	},
+	{
+		[]byte{0x88, 0xB2, 0xB2, 0x70, 0x6B, 0x10, 0x5E, 0x36, 0xB4, 0x46, 0xBB, 0x6D, 0x73, 0x1A, 0x1E, 0x88,
+			0xEF, 0xA7, 0x1F, 0x78, 0x89, 0x65, 0xBD, 0x44},
+		[]byte{0x39, 0xDA, 0x69, 0xD6, 0xBA, 0x49, 0x97, 0xD5, 0x85, 0xB6, 0xDC, 0x07, 0x3C, 0xA3, 0x41, 0xB2},
+		[]byte{0x18, 0x2B, 0x02, 0xD8, 0x14, 0x97, 0xEA, 0x45, 0xF9, 0xDA, 0xAC, 0xDC, 0x29, 0x19, 0x3A, 0x65},
+	},
+	{
+		[]byte{0xD4, 0x3B, 0xB7, 0x55, 0x6E, 0xA3, 0x2E, 0x46, 0xF2, 0xA2, 0x82, 0xB7, 0xD4, 0x5B, 0x4E, 0x0D,
+			0x57, 0xFF, 0x73, 0x9D, 0x4D, 0xC9, 0x2C, 0x1B, 0xD7, 0xFC, 0x01, 0x70, 0x0C, 0xC8, 0x21, 0x6F},
+		[]byte{0x90, 0xAF, 0xE9, 0x1B, 0xB2, 0x88, 0x54, 0x4F, 0x2C, 0x32, 0xDC, 0x23, 0x9B, 0x26, 0x35, 0xE6},
+		[]byte{0x6C, 0xB4, 0x56, 0x1C, 0x40, 0xBF, 0x0A, 0x97, 0x05, 0x93, 0x1C, 0xB6, 0xD4, 0x08, 0xE7, 0xFA},
+	},
+	// These test are derived from http://www.schneier.com/code/ecb_ival.txt
+	{
+		[]byte{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},
+		[]byte{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},
+		[]byte{0x9F, 0x58, 0x9F, 0x5C, 0xF6, 0x12, 0x2C, 0x32, 0xB6, 0xBF, 0xEC, 0x2F, 0x2A, 0xE8, 0xC3, 0x5A},
+	},
+	{
+		[]byte{0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF, 0xFE, 0xDC, 0xBA, 0x98, 0x76, 0x54, 0x32, 0x10,
+			0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77,
+		},
+		[]byte{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},
+		[]byte{0xCF, 0xD1, 0xD2, 0xE5, 0xA9, 0xBE, 0x9C, 0xDF, 0x50, 0x1F, 0x13, 0xB8, 0x92, 0xBD, 0x22, 0x48},
+	},
+	{
+		[]byte{0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF, 0xFE, 0xDC, 0xBA, 0x98, 0x76, 0x54, 0x32, 0x10,
+			0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77, 0x88, 0x99, 0xAA, 0xBB, 0xCC, 0xDD, 0xEE, 0xFF,
+		},
+		[]byte{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},
+		[]byte{0x37, 0x52, 0x7B, 0xE0, 0x05, 0x23, 0x34, 0xB8, 0x9F, 0x0C, 0xFC, 0xCA, 0xE8, 0x7C, 0xFA, 0x20},
+	},
+}
+
+func TestCipher(t *testing.T) {
+	for n, tt := range testVectors {
+		// Test if the plaintext (dec) is encrypts to the given
+		// ciphertext (enc) using the given key. Test also if enc can
+		// be decrypted again into dec.
+		c, err := NewCipher(tt.key)
+		if err != nil {
+			t.Errorf("#%d: NewCipher: %v", n, err)
+			return
+		}
+
+		buf := make([]byte, 16)
+		c.Encrypt(buf, tt.dec)
+		if !bytes.Equal(buf, tt.enc) {
+			t.Errorf("#%d: encrypt = %x want %x", n, buf, tt.enc)
+		}
+		c.Decrypt(buf, tt.enc)
+		if !bytes.Equal(buf, tt.dec) {
+			t.Errorf("#%d: decrypt = %x want %x", n, buf, tt.dec)
+		}
+
+		// Test that 16 zero bytes, encrypted 1000 times then decrypted
+		// 1000 times results in zero bytes again.
+		zero := make([]byte, 16)
+		buf = make([]byte, 16)
+		for i := 0; i < 1000; i++ {
+			c.Encrypt(buf, buf)
+		}
+		for i := 0; i < 1000; i++ {
+			c.Decrypt(buf, buf)
+		}
+		if !bytes.Equal(buf, zero) {
+			t.Errorf("#%d: encrypt/decrypt 1000: have %x want %x", n, buf, zero)
+		}
+	}
+}