crypto/des: new package providing implementations of DES and TDEA

Original code by Chris Lennert <cale...@gmail.com>

R=rsc, agl1
CC=golang-dev
https://golang.org/cl/4331054

src/pkg/crypto/des/Makefile

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+# 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.
+
+include ../../../Make.inc
+
+TARG=crypto/des
+GOFILES=\
+	block.go\
+	cipher.go\
+	const.go\
+
+include ../../../Make.pkg

src/pkg/crypto/des/block.go

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+// 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.
+
+package des
+
+// Encrypt one block from src into dst, using the subkeys.
+func encryptBlock(subkeys [16]uint64, dst, src []byte) {
+	// perform initial permutation
+	permutedSrc := permuteBlock(src, initialPermutation[0:])
+
+	// split into left and right halves
+	left := uint32(permutedSrc >> 32)
+	right := uint32(permutedSrc)
+
+	// process left and right with feistel function
+	for i := 0; i < 16; i++ {
+		previousRight := right
+		right = left ^ feistel(right, subkeys[i])
+		left = previousRight
+	}
+	// switch left & right and perform final permutation
+	preOutput := (uint64(right) << 32) | uint64(left)
+	final := uint64ToBytes(permuteBlock(uint64ToBytes(preOutput), finalPermutation[0:]))
+
+	// copy bytes to destination
+	copy(dst, final)
+}
+
+// Decrypt one block from src into dst, using the subkeys.
+func decryptBlock(subkeys [16]uint64, dst, src []byte) {
+	// perform initial permutation
+	permutedSrc := permuteBlock(src, initialPermutation[0:])
+
+	// split into left and right halves
+	left := uint32(permutedSrc >> 32)
+	right := uint32(permutedSrc)
+
+	// process left and right with feistel function
+	for i := 0; i < 16; i++ {
+		previousRight := right
+		// decryption reverses order of subkeys
+		right = left ^ feistel(right, subkeys[15-i])
+		left = previousRight
+	}
+	// switch left & right and perform final permutation
+	preOutput := (uint64(right) << 32) | uint64(left)
+	final := uint64ToBytes(permuteBlock(uint64ToBytes(preOutput), finalPermutation[0:]))
+
+	// copy bytes to destination
+	copy(dst, final)
+}
+
+// DES Feistel function
+func feistel(right uint32, key uint64) (result uint32) {
+	rightExpanded := permuteBlock(uint32ToBytes(right), expansionFunction[:])
+	xorResult := key ^ rightExpanded
+	var sBoxResult uint32
+	for i := uint8(0); i < 8; i++ {
+		sBoxCoordValue := uint8((xorResult << (16 + (6 * i))) >> 58)
+		// determine the proper S-box row and column from the 6-bits of
+		// sBoxCoordValue row is determined by 1st and 6th bit
+		row := (sBoxCoordValue & 0x1) | ((sBoxCoordValue & 0x20) >> 4)
+		// column is middle four bits
+		column := (sBoxCoordValue << 3) >> 4
+		sBoxResult |= uint32(sBoxes[i][row][column]) << (4 * (7 - i))
+	}
+	return uint32(permuteBlock(uint32ToBytes(sBoxResult), permutationFunction[0:]))
+}
+
+// general purpose function to perform DES block permutations
+func permuteBlock(src []byte, permutation []uint8) (block uint64) {
+	for finalPosition, bitNumber := range permutation {
+		bitIndex := bitNumber - 1
+		byteIndex := bitIndex >> 3
+		bitNumberInByte := bitIndex % 8
+		bitValue := (src[byteIndex] << bitNumberInByte) >> 7
+		block |= uint64(bitValue) << uint64((uint8(len(permutation)-1))-uint8(finalPosition))
+	}
+	return
+}
+
+// creates 16 28-bit blocks rotated according
+// to the rotation schedule
+func ksRotate(in uint32) (out []uint32) {
+	out = make([]uint32, 16)
+	last := in
+	for i := 0; i < 16; i++ {
+		// 28-bit circular left shift
+		part1 := (last << (4 + uint32(ksRotations[i]))) >> 4
+		part2 := (last << 4) >> (32 - ksRotations[i])
+		out[i] = part1 | part2
+		last = out[i]
+	}
+	return
+}
+
+// creates 16 56-bit subkeys from the original key
+func ksGenerateSubkeys(cipher *DESCipher) {
+	// apply PC1 permutation to key
+	permutedKey := permuteBlock(cipher.key, permutedChoice1[0:])
+
+	// rotate halves of permuted key according to the rotation schedule
+	leftRotations := ksRotate(uint32(permutedKey >> 28))
+	rightRotations := ksRotate(uint32(permutedKey<<4) >> 4)
+
+	// generate subkeys
+	for i := 0; i < 16; i++ {
+		// combine halves to form 56-bit input to PC2
+		pc2Input := uint64(leftRotations[i])<<28 | uint64(rightRotations[i])
+		// apply PC2 permutation to 7 byte input
+		cipher.subkeys[i] = permuteBlock(uint64ToBytes(pc2Input)[1:], permutedChoice2[0:])
+	}
+}
+
+// generates a byte array from uint32 input
+func uint32ToBytes(block uint32) []byte {
+	return []byte{
+		byte(block >> 24), byte(block >> 16),
+		byte(block >> 8), byte(block)}
+}
+
+// generates a byte array from uint64 input
+func uint64ToBytes(block uint64) []byte {
+	return []byte{
+		byte(block >> 56), byte(block >> 48),
+		byte(block >> 40), byte(block >> 32),
+		byte(block >> 24), byte(block >> 16),
+		byte(block >> 8), byte(block)}
+}

src/pkg/crypto/des/cipher.go

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+// 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.
+
+package des
+
+import (
+	"os"
+	"strconv"
+)
+
+// The DES block size in bytes.
+const BlockSize = 8
+
+type KeySizeError int
+
+func (k KeySizeError) String() string {
+	return "crypto/des: invalid key size " + strconv.Itoa(int(k))
+}
+
+// A DESCipher is an instance of DES encryption.
+type DESCipher struct {
+	key     []byte
+	subkeys [16]uint64
+}
+
+// NewCipher creates and returns a new Cipher.
+func NewDESCipher(key []byte) (*DESCipher, os.Error) {
+	k := len(key)
+	if k != 8 {
+		return nil, KeySizeError(k)
+	}
+
+	c := &DESCipher{key, [16]uint64{}}
+	ksGenerateSubkeys(c)
+	return c, nil
+}
+
+// BlockSize returns the DES block size, 8 bytes.
+func (c *DESCipher) BlockSize() int { return BlockSize }
+
+// Encrypts the 8-byte buffer src and stores the result in dst.
+// 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/cipher/cbc.go).
+func (c *DESCipher) Encrypt(dst, src []byte) { encryptBlock(c.subkeys, dst, src) }
+
+// Decrypts the 8-byte buffer src and stores the result in dst.
+func (c *DESCipher) Decrypt(dst, src []byte) { decryptBlock(c.subkeys, dst, src) }
+
+// Reset zeros the key data, so that it will no longer
+// appear in the process's memory.
+func (c *DESCipher) Reset() {
+	for i := 0; i < len(c.key); i++ {
+		c.key[i] = 0
+	}
+	for i := 0; i < len(c.subkeys); i++ {
+		c.subkeys[i] = 0
+	}
+}
+
+// A TripleDESCipher is an instance of TripleDES encryption.
+type TripleDESCipher struct {
+	key                       []byte
+	cipher1, cipher2, cipher3 *DESCipher
+}
+
+// NewCipher creates and returns a new Cipher.
+func NewTripleDESCipher(key []byte) (*TripleDESCipher, os.Error) {
+	k := len(key)
+	if k != 24 {
+		return nil, KeySizeError(k)
+	}
+
+	cipher1, _ := NewDESCipher(key[0:8])
+	cipher2, _ := NewDESCipher(key[8:16])
+	cipher3, _ := NewDESCipher(key[16:])
+	c := &TripleDESCipher{key, cipher1, cipher2, cipher3}
+	return c, nil
+}
+
+// BlockSize returns the TripleDES block size, 8 bytes.
+// It is necessary to satisfy the Block interface in the
+// package "crypto/cipher".
+func (c *TripleDESCipher) BlockSize() int { return BlockSize }
+
+// Encrypts the 8-byte buffer src and stores the result in dst.
+// 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/cipher/cbc.go).
+func (c *TripleDESCipher) Encrypt(dst, src []byte) {
+	c.cipher1.Encrypt(dst, src)
+	c.cipher2.Decrypt(dst, dst)
+	c.cipher3.Encrypt(dst, dst)
+}
+
+// Decrypts the 8-byte buffer src and stores the result in dst.
+func (c *TripleDESCipher) Decrypt(dst, src []byte) {
+	c.cipher3.Decrypt(dst, src)
+	c.cipher2.Encrypt(dst, dst)
+	c.cipher1.Decrypt(dst, dst)
+}
+
+// Reset zeros the key data, so that it will no longer
+// appear in the process's memory.
+func (c *TripleDESCipher) Reset() {
+	for i := 0; i < len(c.key); i++ {
+		c.key[i] = 0
+	}
+	c.cipher1.Reset()
+	c.cipher2.Reset()
+	c.cipher3.Reset()
+}

src/pkg/crypto/des/const.go

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+// 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.
+
+// Package des implements the Data Encryption Standard (DES) and the
+// Triple Data Encryption Algorithm (TDEA) as defined
+// in U.S. Federal Information Processing Standards Publication 46-3.
+package des
+
+// Used to perform an initial permutation of a
+// 64-bit input block
+var initialPermutation = [64]uint8{
+	58, 50, 42, 34, 26, 18, 10, 2,
+	60, 52, 44, 36, 28, 20, 12, 4,
+	62, 54, 46, 38, 30, 22, 14, 6,
+	64, 56, 48, 40, 32, 24, 16, 8,
+	57, 49, 41, 33, 25, 17, 9, 1,
+	59, 51, 43, 35, 27, 19, 11, 3,
+	61, 53, 45, 37, 29, 21, 13, 5,
+	63, 55, 47, 39, 31, 23, 15, 7}
+
+// Used to perform a final permutation of a
+// 64-bit preoutput block
+// This is the inverse of initialPermutation
+var finalPermutation = [64]uint8{
+	40, 8, 48, 16, 56, 24, 64, 32,
+	39, 7, 47, 15, 55, 23, 63, 31,
+	38, 6, 46, 14, 54, 22, 62, 30,
+	37, 5, 45, 13, 53, 21, 61, 29,
+	36, 4, 44, 12, 52, 20, 60, 28,
+	35, 3, 43, 11, 51, 19, 59, 27,
+	34, 2, 42, 10, 50, 18, 58, 26,
+	33, 1, 41, 9, 49, 17, 57, 25}
+
+// Used to expand an input block of 32 bits,
+// producing an output block of 48 bits.
+var expansionFunction = [48]uint8{
+	32, 1, 2, 3, 4, 5,
+	4, 5, 6, 7, 8, 9,
+	8, 9, 10, 11, 12, 13,
+	12, 13, 14, 15, 16, 17,
+	16, 17, 18, 19, 20, 21,
+	20, 21, 22, 23, 24, 25,
+	24, 25, 26, 27, 28, 29,
+	28, 29, 30, 31, 32, 1}
+
+// Yields a 32-bit output from a 32-bit input
+var permutationFunction = [32]uint8{
+	16, 7, 20, 21,
+	29, 12, 28, 17,
+	1, 15, 23, 26,
+	5, 18, 31, 10,
+	2, 8, 24, 14,
+	32, 27, 3, 9,
+	19, 13, 30, 6,
+	22, 11, 4, 25}
+
+// Used in the key schedule to select 56 bits
+// from a 64-bit input.
+var permutedChoice1 = [56]uint8{
+	// left
+	57, 49, 41, 33, 25, 17, 9,
+	1, 58, 50, 42, 34, 26, 18,
+	10, 2, 59, 51, 43, 35, 27,
+	19, 11, 3, 60, 52, 44, 36,
+	// right
+	63, 55, 47, 39, 31, 23, 15,
+	7, 62, 54, 46, 38, 30, 22,
+	14, 6, 61, 53, 45, 37, 29,
+	21, 13, 5, 28, 20, 12, 4}
+
+// Used in the key schedule to produce
+// each subkey by selecting 48 bits
+// from the 56-bit input
+var permutedChoice2 = [48]uint8{
+	14, 17, 11, 24, 1, 5,
+	3, 28, 15, 6, 21, 10,
+	23, 19, 12, 4, 26, 8,
+	16, 7, 27, 20, 13, 2,
+	41, 52, 31, 37, 47, 55,
+	30, 40, 51, 45, 33, 48,
+	44, 49, 39, 56, 34, 53,
+	46, 42, 50, 36, 29, 32}
+
+// 8 S-boxes composed of 4 rows and 16 columns
+// Used in the DES cipher function
+var sBoxes = [8][4][16]uint8{
+	// S-box 1
+	{
+		[16]uint8{14, 4, 13, 1, 2, 15, 11, 8, 3, 10, 6, 12, 5, 9, 0, 7},
+		[16]uint8{0, 15, 7, 4, 14, 2, 13, 1, 10, 6, 12, 11, 9, 5, 3, 8},
+		[16]uint8{4, 1, 14, 8, 13, 6, 2, 11, 15, 12, 9, 7, 3, 10, 5, 0},
+		[16]uint8{15, 12, 8, 2, 4, 9, 1, 7, 5, 11, 3, 14, 10, 0, 6, 13}},
+	// S-box 2
+	{
+		[16]uint8{15, 1, 8, 14, 6, 11, 3, 4, 9, 7, 2, 13, 12, 0, 5, 10},
+		[16]uint8{3, 13, 4, 7, 15, 2, 8, 14, 12, 0, 1, 10, 6, 9, 11, 5},
+		[16]uint8{0, 14, 7, 11, 10, 4, 13, 1, 5, 8, 12, 6, 9, 3, 2, 15},
+		[16]uint8{13, 8, 10, 1, 3, 15, 4, 2, 11, 6, 7, 12, 0, 5, 14, 9}},
+	// S-box 3
+	{
+		[16]uint8{10, 0, 9, 14, 6, 3, 15, 5, 1, 13, 12, 7, 11, 4, 2, 8},
+		[16]uint8{13, 7, 0, 9, 3, 4, 6, 10, 2, 8, 5, 14, 12, 11, 15, 1},
+		[16]uint8{13, 6, 4, 9, 8, 15, 3, 0, 11, 1, 2, 12, 5, 10, 14, 7},
+		[16]uint8{1, 10, 13, 0, 6, 9, 8, 7, 4, 15, 14, 3, 11, 5, 2, 12}},
+	// S-box 4
+	{
+		[16]uint8{7, 13, 14, 3, 0, 6, 9, 10, 1, 2, 8, 5, 11, 12, 4, 15},
+		[16]uint8{13, 8, 11, 5, 6, 15, 0, 3, 4, 7, 2, 12, 1, 10, 14, 9},
+		[16]uint8{10, 6, 9, 0, 12, 11, 7, 13, 15, 1, 3, 14, 5, 2, 8, 4},
+		[16]uint8{3, 15, 0, 6, 10, 1, 13, 8, 9, 4, 5, 11, 12, 7, 2, 14}},
+	// S-box 5
+	{
+		[16]uint8{2, 12, 4, 1, 7, 10, 11, 6, 8, 5, 3, 15, 13, 0, 14, 9},
+		[16]uint8{14, 11, 2, 12, 4, 7, 13, 1, 5, 0, 15, 10, 3, 9, 8, 6},
+		[16]uint8{4, 2, 1, 11, 10, 13, 7, 8, 15, 9, 12, 5, 6, 3, 0, 14},
+		[16]uint8{11, 8, 12, 7, 1, 14, 2, 13, 6, 15, 0, 9, 10, 4, 5, 3}},
+	// S-box 6
+	{
+		[16]uint8{12, 1, 10, 15, 9, 2, 6, 8, 0, 13, 3, 4, 14, 7, 5, 11},
+		[16]uint8{10, 15, 4, 2, 7, 12, 9, 5, 6, 1, 13, 14, 0, 11, 3, 8},
+		[16]uint8{9, 14, 15, 5, 2, 8, 12, 3, 7, 0, 4, 10, 1, 13, 11, 6},
+		[16]uint8{4, 3, 2, 12, 9, 5, 15, 10, 11, 14, 1, 7, 6, 0, 8, 13}},
+	// S-box 7
+	{
+		[16]uint8{4, 11, 2, 14, 15, 0, 8, 13, 3, 12, 9, 7, 5, 10, 6, 1},
+		[16]uint8{13, 0, 11, 7, 4, 9, 1, 10, 14, 3, 5, 12, 2, 15, 8, 6},
+		[16]uint8{1, 4, 11, 13, 12, 3, 7, 14, 10, 15, 6, 8, 0, 5, 9, 2},
+		[16]uint8{6, 11, 13, 8, 1, 4, 10, 7, 9, 5, 0, 15, 14, 2, 3, 12}},
+	// S-box 8
+	{
+		[16]uint8{13, 2, 8, 4, 6, 15, 11, 1, 10, 9, 3, 14, 5, 0, 12, 7},
+		[16]uint8{1, 15, 13, 8, 10, 3, 7, 4, 12, 5, 6, 11, 0, 14, 9, 2},
+		[16]uint8{7, 11, 4, 1, 9, 12, 14, 2, 0, 6, 10, 13, 15, 3, 5, 8},
+		[16]uint8{2, 1, 14, 7, 4, 10, 8, 13, 15, 12, 9, 0, 3, 5, 6, 11}}}
+
+// Size of left rotation per round in each half of the key schedule
+var ksRotations = [16]uint8{1, 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 1}