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

5 files changed, 500 insertions, 0 deletions

diff --git a/CONTRIBUTORS b/CONTRIBUTORS
index 0f08c55aae..823561cb11 100644
--- a/CONTRIBUTORS
+++ b/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>
diff --git a/src/pkg/Makefile b/src/pkg/Makefile
index 7582aba3de..05e2a26d1f 100644
--- a/src/pkg/Makefile
+++ b/src/pkg/Makefile
@@ -47,6 +47,7 @@ DIRS=\
 	crypto/sha512\
 	crypto/subtle\
 	crypto/tls\
+	crypto/twofish\
 	crypto/x509\
 	crypto/xtea\
 	debug/dwarf\
diff --git a/src/pkg/crypto/twofish/Makefile b/src/pkg/crypto/twofish/Makefile
new file mode 100644
index 0000000000..aec61659d7
--- /dev/null
+++ b/src/pkg/crypto/twofish/Makefile
@@ -0,0 +1,11 @@
+# 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
diff --git a/src/pkg/crypto/twofish/twofish.go b/src/pkg/crypto/twofish/twofish.go
new file mode 100644
index 0000000000..b362c44d29
--- /dev/null
+++ b/src/pkg/crypto/twofish/twofish.go
@@ -0,0 +1,358 @@
+// 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.
+
+// This package implements Bruce Schneier's Twofish encryption algorithm.
+package twofish
+
+// Twofish is defined in http://www.schneier.com/paper-twofish-paper.pdf [TWOFISH]
+
+// This code is a port of the LibTom C implementation.
+// See http://libtom.org/?page=features&newsitems=5&whatfile=crypt.
+// LibTomCrypt is free for all purposes under the public domain.
+// It was heavily inspired by the go blowfish package.
+
+import (
+	"os"
+	"strconv"
+)
+
+// BlockSize is the constant block size of Twofish.
+const BlockSize = 16
+
+const mdsPolynomial = 0x169 // x^8 + x^6 + x^5 + x^3 + 1, see [TWOFISH] 4.2
+const rsPolynomial = 0x14d  // x^8 + x^6 + x^3 + x^2 + 1, see [TWOFISH] 4.3
+
+// A Cipher is an instance of Twofish encryption using a particular key.
+type Cipher struct {
+	s [4][256]uint32
+	k [40]uint32
+}
+
+type KeySizeError int
+
+func (k KeySizeError) String() string {
+	return "crypto/twofish: invalid key size " + strconv.Itoa(int(k))
+}
+
+// NewCipher creates and returns a Cipher.
+// The key argument should be the Twofish key, 16, 24 or 32 bytes.
+func NewCipher(key []byte) (*Cipher, os.Error) {
+	keylen := len(key)
+
+	if keylen != 16 && keylen != 24 && keylen != 32 {
+		return nil, KeySizeError(keylen)
+	}
+
+	// k is the number of 64 bit words in key
+	k := keylen / 8
+
+	// Create the S[..] words
+	var S [4 * 4]byte
+	for i := 0; i < k; i++ {
+		// Computes [y0 y1 y2 y3] = rs . [x0 x1 x2 x3 x4 x5 x6 x7]
+		for j := 0; j < 4; j++ {
+			for k := 0; k < 8; k++ {
+				S[4*i+j] ^= gfMult(key[8*i+k], rs[j][k], rsPolynomial)
+			}
+		}
+	}
+
+	// Calculate subkeys
+	c := new(Cipher)
+	var tmp [4]byte
+	for i := byte(0); i < 20; i++ {
+		// A = h(p * 2x, Me)
+		for j := 0; j < 4; j++ {
+			tmp[j] = 2 * i
+		}
+		A := h(tmp[:], key, 0)
+
+		// B = rolc(h(p * (2x + 1), Mo), 8)
+		for j := 0; j < 4; j++ {
+			tmp[j] = 2*i + 1
+		}
+		B := h(tmp[:], key, 1)
+		B = rol(B, 8)
+
+		c.k[2*i] = A + B
+
+		// K[2i+1] = (A + 2B) <<< 9
+		c.k[2*i+1] = rol(2*B+A, 9)
+	}
+
+	// Calculate sboxes
+	switch k {
+	case 2:
+		for i := 0; i <= 255; i++ {
+			c.s[0][i] = mdsColumnMult(sbox[1][sbox[0][sbox[0][byte(i)]^S[0]]^S[4]], 0)
+			c.s[1][i] = mdsColumnMult(sbox[0][sbox[0][sbox[1][byte(i)]^S[1]]^S[5]], 1)
+			c.s[2][i] = mdsColumnMult(sbox[1][sbox[1][sbox[0][byte(i)]^S[2]]^S[6]], 2)
+			c.s[3][i] = mdsColumnMult(sbox[0][sbox[1][sbox[1][byte(i)]^S[3]]^S[7]], 3)
+		}
+	case 3:
+		for i := 0; i < 256; i++ {
+			c.s[0][i] = mdsColumnMult(sbox[1][sbox[0][sbox[0][sbox[1][byte(i)]^S[0]]^S[4]]^S[8]], 0)
+			c.s[1][i] = mdsColumnMult(sbox[0][sbox[0][sbox[1][sbox[1][byte(i)]^S[1]]^S[5]]^S[9]], 1)
+			c.s[2][i] = mdsColumnMult(sbox[1][sbox[1][sbox[0][sbox[0][byte(i)]^S[2]]^S[6]]^S[10]], 2)
+			c.s[3][i] = mdsColumnMult(sbox[0][sbox[1][sbox[1][sbox[0][byte(i)]^S[3]]^S[7]]^S[11]], 3)
+		}
+	default:
+		for i := 0; i < 256; i++ {
+			c.s[0][i] = mdsColumnMult(sbox[1][sbox[0][sbox[0][sbox[1][sbox[1][byte(i)]^S[0]]^S[4]]^S[8]]^S[12]], 0)
+			c.s[1][i] = mdsColumnMult(sbox[0][sbox[0][sbox[1][sbox[1][sbox[0][byte(i)]^S[1]]^S[5]]^S[9]]^S[13]], 1)
+			c.s[2][i] = mdsColumnMult(sbox[1][sbox[1][sbox[0][sbox[0][sbox[0][byte(i)]^S[2]]^S[6]]^S[10]]^S[14]], 2)
+			c.s[3][i] = mdsColumnMult(sbox[0][sbox[1][sbox[1][sbox[0][sbox[1][byte(i)]^S[3]]^S[7]]^S[11]]^S[15]], 3)
+		}
+	}
+
+	return c, nil
+}
+
+// Reset zeros the key data, so that it will no longer appear in the process's
+// memory.
+func (c *Cipher) Reset() {
+	for i := 0; i < 40; i++ {
+		c.k[i] = 0
+	}
+	for i := 0; i < 4; i++ {
+		for j := 0; j < 265; j++ {
+			c.s[i][j] = 0
+		}
+	}
+}
+
+// BlockSize returns the Twofish block size, 16 bytes.
+func (c *Cipher) BlockSize() int { return BlockSize }
+
+// store32l stores src in dst in little-endian form.
+func store32l(dst []byte, src uint32) {
+	dst[0] = byte(src)
+	dst[1] = byte(src >> 8)
+	dst[2] = byte(src >> 16)
+	dst[3] = byte(src >> 24)
+	return
+}
+
+// load32l reads a little-endian uint32 from src.
+func load32l(src []byte) uint32 {
+	return uint32(src[0]) | uint32(src[1])<<8 | uint32(src[2])<<16 | uint32(src[3])<<24
+}
+
+// rol returns x after a left circular rotation of y bits.
+func rol(x, y uint32) uint32 {
+	return (x << (y & 31)) | (x >> (32 - (y & 31)))
+}
+
+// ror returns x after a right circular rotation of y bits.
+func ror(x, y uint32) uint32 {
+	return (x >> (y & 31)) | (x << (32 - (y & 31)))
+}
+
+// The RS matrix. See [TWOFISH] 4.3
+var rs = [4][8]byte{
+	{0x01, 0xA4, 0x55, 0x87, 0x5A, 0x58, 0xDB, 0x9E},
+	{0xA4, 0x56, 0x82, 0xF3, 0x1E, 0xC6, 0x68, 0xE5},
+	{0x02, 0xA1, 0xFC, 0xC1, 0x47, 0xAE, 0x3D, 0x19},
+	{0xA4, 0x55, 0x87, 0x5A, 0x58, 0xDB, 0x9E, 0x03},
+}
+
+// sbox tables
+var sbox = [2][256]byte{
+	{
+		0xa9, 0x67, 0xb3, 0xe8, 0x04, 0xfd, 0xa3, 0x76, 0x9a, 0x92, 0x80, 0x78, 0xe4, 0xdd, 0xd1, 0x38,
+		0x0d, 0xc6, 0x35, 0x98, 0x18, 0xf7, 0xec, 0x6c, 0x43, 0x75, 0x37, 0x26, 0xfa, 0x13, 0x94, 0x48,
+		0xf2, 0xd0, 0x8b, 0x30, 0x84, 0x54, 0xdf, 0x23, 0x19, 0x5b, 0x3d, 0x59, 0xf3, 0xae, 0xa2, 0x82,
+		0x63, 0x01, 0x83, 0x2e, 0xd9, 0x51, 0x9b, 0x7c, 0xa6, 0xeb, 0xa5, 0xbe, 0x16, 0x0c, 0xe3, 0x61,
+		0xc0, 0x8c, 0x3a, 0xf5, 0x73, 0x2c, 0x25, 0x0b, 0xbb, 0x4e, 0x89, 0x6b, 0x53, 0x6a, 0xb4, 0xf1,
+		0xe1, 0xe6, 0xbd, 0x45, 0xe2, 0xf4, 0xb6, 0x66, 0xcc, 0x95, 0x03, 0x56, 0xd4, 0x1c, 0x1e, 0xd7,
+		0xfb, 0xc3, 0x8e, 0xb5, 0xe9, 0xcf, 0xbf, 0xba, 0xea, 0x77, 0x39, 0xaf, 0x33, 0xc9, 0x62, 0x71,
+		0x81, 0x79, 0x09, 0xad, 0x24, 0xcd, 0xf9, 0xd8, 0xe5, 0xc5, 0xb9, 0x4d, 0x44, 0x08, 0x86, 0xe7,
+		0xa1, 0x1d, 0xaa, 0xed, 0x06, 0x70, 0xb2, 0xd2, 0x41, 0x7b, 0xa0, 0x11, 0x31, 0xc2, 0x27, 0x90,
+		0x20, 0xf6, 0x60, 0xff, 0x96, 0x5c, 0xb1, 0xab, 0x9e, 0x9c, 0x52, 0x1b, 0x5f, 0x93, 0x0a, 0xef,
+		0x91, 0x85, 0x49, 0xee, 0x2d, 0x4f, 0x8f, 0x3b, 0x47, 0x87, 0x6d, 0x46, 0xd6, 0x3e, 0x69, 0x64,
+		0x2a, 0xce, 0xcb, 0x2f, 0xfc, 0x97, 0x05, 0x7a, 0xac, 0x7f, 0xd5, 0x1a, 0x4b, 0x0e, 0xa7, 0x5a,
+		0x28, 0x14, 0x3f, 0x29, 0x88, 0x3c, 0x4c, 0x02, 0xb8, 0xda, 0xb0, 0x17, 0x55, 0x1f, 0x8a, 0x7d,
+		0x57, 0xc7, 0x8d, 0x74, 0xb7, 0xc4, 0x9f, 0x72, 0x7e, 0x15, 0x22, 0x12, 0x58, 0x07, 0x99, 0x34,
+		0x6e, 0x50, 0xde, 0x68, 0x65, 0xbc, 0xdb, 0xf8, 0xc8, 0xa8, 0x2b, 0x40, 0xdc, 0xfe, 0x32, 0xa4,
+		0xca, 0x10, 0x21, 0xf0, 0xd3, 0x5d, 0x0f, 0x00, 0x6f, 0x9d, 0x36, 0x42, 0x4a, 0x5e, 0xc1, 0xe0,
+	},
+	{
+		0x75, 0xf3, 0xc6, 0xf4, 0xdb, 0x7b, 0xfb, 0xc8, 0x4a, 0xd3, 0xe6, 0x6b, 0x45, 0x7d, 0xe8, 0x4b,
+		0xd6, 0x32, 0xd8, 0xfd, 0x37, 0x71, 0xf1, 0xe1, 0x30, 0x0f, 0xf8, 0x1b, 0x87, 0xfa, 0x06, 0x3f,
+		0x5e, 0xba, 0xae, 0x5b, 0x8a, 0x00, 0xbc, 0x9d, 0x6d, 0xc1, 0xb1, 0x0e, 0x80, 0x5d, 0xd2, 0xd5,
+		0xa0, 0x84, 0x07, 0x14, 0xb5, 0x90, 0x2c, 0xa3, 0xb2, 0x73, 0x4c, 0x54, 0x92, 0x74, 0x36, 0x51,
+		0x38, 0xb0, 0xbd, 0x5a, 0xfc, 0x60, 0x62, 0x96, 0x6c, 0x42, 0xf7, 0x10, 0x7c, 0x28, 0x27, 0x8c,
+		0x13, 0x95, 0x9c, 0xc7, 0x24, 0x46, 0x3b, 0x70, 0xca, 0xe3, 0x85, 0xcb, 0x11, 0xd0, 0x93, 0xb8,
+		0xa6, 0x83, 0x20, 0xff, 0x9f, 0x77, 0xc3, 0xcc, 0x03, 0x6f, 0x08, 0xbf, 0x40, 0xe7, 0x2b, 0xe2,
+		0x79, 0x0c, 0xaa, 0x82, 0x41, 0x3a, 0xea, 0xb9, 0xe4, 0x9a, 0xa4, 0x97, 0x7e, 0xda, 0x7a, 0x17,
+		0x66, 0x94, 0xa1, 0x1d, 0x3d, 0xf0, 0xde, 0xb3, 0x0b, 0x72, 0xa7, 0x1c, 0xef, 0xd1, 0x53, 0x3e,
+		0x8f, 0x33, 0x26, 0x5f, 0xec, 0x76, 0x2a, 0x49, 0x81, 0x88, 0xee, 0x21, 0xc4, 0x1a, 0xeb, 0xd9,
+		0xc5, 0x39, 0x99, 0xcd, 0xad, 0x31, 0x8b, 0x01, 0x18, 0x23, 0xdd, 0x1f, 0x4e, 0x2d, 0xf9, 0x48,
+		0x4f, 0xf2, 0x65, 0x8e, 0x78, 0x5c, 0x58, 0x19, 0x8d, 0xe5, 0x98, 0x57, 0x67, 0x7f, 0x05, 0x64,
+		0xaf, 0x63, 0xb6, 0xfe, 0xf5, 0xb7, 0x3c, 0xa5, 0xce, 0xe9, 0x68, 0x44, 0xe0, 0x4d, 0x43, 0x69,
+		0x29, 0x2e, 0xac, 0x15, 0x59, 0xa8, 0x0a, 0x9e, 0x6e, 0x47, 0xdf, 0x34, 0x35, 0x6a, 0xcf, 0xdc,
+		0x22, 0xc9, 0xc0, 0x9b, 0x89, 0xd4, 0xed, 0xab, 0x12, 0xa2, 0x0d, 0x52, 0xbb, 0x02, 0x2f, 0xa9,
+		0xd7, 0x61, 0x1e, 0xb4, 0x50, 0x04, 0xf6, 0xc2, 0x16, 0x25, 0x86, 0x56, 0x55, 0x09, 0xbe, 0x91,
+	},
+}
+
+// gfMult returns a·b in GF(2^8)/p
+func gfMult(a, b byte, p uint32) byte {
+	B := [2]uint32{0, uint32(b)}
+	P := [2]uint32{0, p}
+	var result uint32
+
+	// branchless GF multiplier
+	for i := 0; i < 7; i++ {
+		result ^= B[a&1]
+		a >>= 1
+		B[1] = P[B[1]>>7] ^ (B[1] << 1)
+	}
+	result ^= B[a&1]
+	return byte(result)
+}
+
+// mdsColumnMult calculates y{col} where [y0 y1 y2 y3] = MDS . [x0]
+func mdsColumnMult(in byte, col int) uint32 {
+	mul01 := in
+	mul5B := gfMult(in, 0x5B, mdsPolynomial)
+	mulEF := gfMult(in, 0xEF, mdsPolynomial)
+
+	switch col {
+	case 0:
+		return uint32(mul01) | uint32(mul5B)<<8 | uint32(mulEF)<<16 | uint32(mulEF)<<24
+	case 1:
+		return uint32(mulEF) | uint32(mulEF)<<8 | uint32(mul5B)<<16 | uint32(mul01)<<24
+	case 2:
+		return uint32(mul5B) | uint32(mulEF)<<8 | uint32(mul01)<<16 | uint32(mulEF)<<24
+	case 3:
+		return uint32(mul5B) | uint32(mul01)<<8 | uint32(mulEF)<<16 | uint32(mul5B)<<24
+	}
+
+	panic("unreachable")
+}
+
+// h implements the S-box generation function. See [TWOFISH] 4.3.5
+func h(in, key []byte, offset int) uint32 {
+	var y [4]byte
+	for x := 0; x < 4; x++ {
+		y[x] = in[x]
+	}
+	switch len(key) / 8 {
+	case 4:
+		y[0] = sbox[1][y[0]] ^ key[4*(6+offset)+0]
+		y[1] = sbox[0][y[1]] ^ key[4*(6+offset)+1]
+		y[2] = sbox[0][y[2]] ^ key[4*(6+offset)+2]
+		y[3] = sbox[1][y[3]] ^ key[4*(6+offset)+3]
+		fallthrough
+	case 3:
+		y[0] = sbox[1][y[0]] ^ key[4*(4+offset)+0]
+		y[1] = sbox[1][y[1]] ^ key[4*(4+offset)+1]
+		y[2] = sbox[0][y[2]] ^ key[4*(4+offset)+2]
+		y[3] = sbox[0][y[3]] ^ key[4*(4+offset)+3]
+		fallthrough
+	case 2:
+		y[0] = sbox[1][sbox[0][sbox[0][y[0]]^key[4*(2+offset)+0]]^key[4*(0+offset)+0]]
+		y[1] = sbox[0][sbox[0][sbox[1][y[1]]^key[4*(2+offset)+1]]^key[4*(0+offset)+1]]
+		y[2] = sbox[1][sbox[1][sbox[0][y[2]]^key[4*(2+offset)+2]]^key[4*(0+offset)+2]]
+		y[3] = sbox[0][sbox[1][sbox[1][y[3]]^key[4*(2+offset)+3]]^key[4*(0+offset)+3]]
+	}
+	// [y0 y1 y2 y3] = MDS . [x0 x1 x2 x3]
+	var mdsMult uint32
+	for i := 0; i < 4; i++ {
+		mdsMult ^= mdsColumnMult(y[i], i)
+	}
+	return mdsMult
+}
+
+// Encrypt encrypts a 16-byte block from src to dst, which may overlap.
+// Note that for amounts of data larger than a block,
+// it is not safe to just call Encrypt on successive blocks;
+// instead, use an encryption mode like CBC (see crypto/block/cbc.go).
+func (skey *Cipher) Encrypt(dst, src []byte) {
+	S1 := skey.s[0]
+	S2 := skey.s[1]
+	S3 := skey.s[2]
+	S4 := skey.s[3]
+
+	// Load input
+	a := load32l(src[0:4])
+	b := load32l(src[4:8])
+	c := load32l(src[8:12])
+	d := load32l(src[12:16])
+
+	// Pre-whitening
+	a ^= skey.k[0]
+	b ^= skey.k[1]
+	c ^= skey.k[2]
+	d ^= skey.k[3]
+
+	for i := 0; i < 8; i++ {
+		k := skey.k[8+i*4 : 12+i*4]
+		t2 := S2[byte(b)] ^ S3[byte(b>>8)] ^ S4[byte(b>>16)] ^ S1[byte(b>>24)]
+		t1 := S1[byte(a)] ^ S2[byte(a>>8)] ^ S3[byte(a>>16)] ^ S4[byte(a>>24)] + t2
+		c = ror(c^(t1+k[0]), 1)
+		d = rol(d, 1) ^ (t2 + t1 + k[1])
+
+		t2 = S2[byte(d)] ^ S3[byte(d>>8)] ^ S4[byte(d>>16)] ^ S1[byte(d>>24)]
+		t1 = S1[byte(c)] ^ S2[byte(c>>8)] ^ S3[byte(c>>16)] ^ S4[byte(c>>24)] + t2
+		a = ror(a^(t1+k[2]), 1)
+		b = rol(b, 1) ^ (t2 + t1 + k[3])
+	}
+
+	// Output with "undo last swap"
+	ta := c ^ skey.k[4]
+	tb := d ^ skey.k[5]
+	tc := a ^ skey.k[6]
+	td := b ^ skey.k[7]
+
+	store32l(dst[0:4], ta)
+	store32l(dst[4:8], tb)
+	store32l(dst[8:12], tc)
+	store32l(dst[12:16], td)
+}
+
+// Decrypt decrypts a 16-byte block from src to dst, which may overlap.
+func (skey *Cipher) Decrypt(dst, src []byte) {
+	S1 := skey.s[0]
+	S2 := skey.s[1]
+	S3 := skey.s[2]
+	S4 := skey.s[3]
+
+	// Load input
+	ta := load32l(src[0:4])
+	tb := load32l(src[4:8])
+	tc := load32l(src[8:12])
+	td := load32l(src[12:16])
+
+	// Undo undo final swap
+	a := tc ^ skey.k[6]
+	b := td ^ skey.k[7]
+	c := ta ^ skey.k[4]
+	d := tb ^ skey.k[5]
+
+	for i := 8; i > 0; i-- {
+		k := skey.k[4+i*4 : 8+i*4]
+		t2 := S2[byte(d)] ^ S3[byte(d>>8)] ^ S4[byte(d>>16)] ^ S1[byte(d>>24)]
+		t1 := S1[byte(c)] ^ S2[byte(c>>8)] ^ S3[byte(c>>16)] ^ S4[byte(c>>24)] + t2
+		a = rol(a, 1) ^ (t1 + k[2])
+		b = ror(b^(t2+t1+k[3]), 1)
+
+		t2 = S2[byte(b)] ^ S3[byte(b>>8)] ^ S4[byte(b>>16)] ^ S1[byte(b>>24)]
+		t1 = S1[byte(a)] ^ S2[byte(a>>8)] ^ S3[byte(a>>16)] ^ S4[byte(a>>24)] + t2
+		c = rol(c, 1) ^ (t1 + k[0])
+		d = ror(d^(t2+t1+k[1]), 1)
+	}
+
+	// Undo pre-whitening
+	a ^= skey.k[0]
+	b ^= skey.k[1]
+	c ^= skey.k[2]
+	d ^= skey.k[3]
+
+	store32l(dst[0:4], a)
+	store32l(dst[4:8], b)
+	store32l(dst[8:12], c)
+	store32l(dst[12:16], d)
+}
diff --git a/src/pkg/crypto/twofish/twofish_test.go b/src/pkg/crypto/twofish/twofish_test.go
new file mode 100644
index 0000000000..96ca6797a4
--- /dev/null
+++ b/src/pkg/crypto/twofish/twofish_test.go
@@ -0,0 +1,129 @@
+// 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)
+		}
+	}
+}