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- // 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 des
- import (
- "crypto/cipher"
- "crypto/internal/subtle"
- "encoding/binary"
- "strconv"
- )
- // The DES block size in bytes.
- const BlockSize = 8
- type KeySizeError int
- func (k KeySizeError) Error() string {
- return "crypto/des: invalid key size " + strconv.Itoa(int(k))
- }
- // desCipher is an instance of DES encryption.
- type desCipher struct {
- subkeys [16]uint64
- }
- // NewCipher creates and returns a new cipher.Block.
- func NewCipher(key []byte) (cipher.Block, error) {
- if len(key) != 8 {
- return nil, KeySizeError(len(key))
- }
- c := new(desCipher)
- c.generateSubkeys(key)
- return c, nil
- }
- func (c *desCipher) BlockSize() int { return BlockSize }
- func (c *desCipher) Encrypt(dst, src []byte) {
- if len(src) < BlockSize {
- panic("crypto/des: input not full block")
- }
- if len(dst) < BlockSize {
- panic("crypto/des: output not full block")
- }
- if subtle.InexactOverlap(dst[:BlockSize], src[:BlockSize]) {
- panic("crypto/des: invalid buffer overlap")
- }
- encryptBlock(c.subkeys[:], dst, src)
- }
- func (c *desCipher) Decrypt(dst, src []byte) {
- if len(src) < BlockSize {
- panic("crypto/des: input not full block")
- }
- if len(dst) < BlockSize {
- panic("crypto/des: output not full block")
- }
- if subtle.InexactOverlap(dst[:BlockSize], src[:BlockSize]) {
- panic("crypto/des: invalid buffer overlap")
- }
- decryptBlock(c.subkeys[:], dst, src)
- }
- // A tripleDESCipher is an instance of TripleDES encryption.
- type tripleDESCipher struct {
- cipher1, cipher2, cipher3 desCipher
- }
- // NewTripleDESCipher creates and returns a new cipher.Block.
- func NewTripleDESCipher(key []byte) (cipher.Block, error) {
- if len(key) != 24 {
- return nil, KeySizeError(len(key))
- }
- c := new(tripleDESCipher)
- c.cipher1.generateSubkeys(key[:8])
- c.cipher2.generateSubkeys(key[8:16])
- c.cipher3.generateSubkeys(key[16:])
- return c, nil
- }
- func (c *tripleDESCipher) BlockSize() int { return BlockSize }
- func (c *tripleDESCipher) Encrypt(dst, src []byte) {
- if len(src) < BlockSize {
- panic("crypto/des: input not full block")
- }
- if len(dst) < BlockSize {
- panic("crypto/des: output not full block")
- }
- if subtle.InexactOverlap(dst[:BlockSize], src[:BlockSize]) {
- panic("crypto/des: invalid buffer overlap")
- }
- b := binary.BigEndian.Uint64(src)
- b = permuteInitialBlock(b)
- left, right := uint32(b>>32), uint32(b)
- left = (left << 1) | (left >> 31)
- right = (right << 1) | (right >> 31)
- for i := 0; i < 8; i++ {
- left, right = feistel(left, right, c.cipher1.subkeys[2*i], c.cipher1.subkeys[2*i+1])
- }
- for i := 0; i < 8; i++ {
- right, left = feistel(right, left, c.cipher2.subkeys[15-2*i], c.cipher2.subkeys[15-(2*i+1)])
- }
- for i := 0; i < 8; i++ {
- left, right = feistel(left, right, c.cipher3.subkeys[2*i], c.cipher3.subkeys[2*i+1])
- }
- left = (left << 31) | (left >> 1)
- right = (right << 31) | (right >> 1)
- preOutput := (uint64(right) << 32) | uint64(left)
- binary.BigEndian.PutUint64(dst, permuteFinalBlock(preOutput))
- }
- func (c *tripleDESCipher) Decrypt(dst, src []byte) {
- if len(src) < BlockSize {
- panic("crypto/des: input not full block")
- }
- if len(dst) < BlockSize {
- panic("crypto/des: output not full block")
- }
- if subtle.InexactOverlap(dst[:BlockSize], src[:BlockSize]) {
- panic("crypto/des: invalid buffer overlap")
- }
- b := binary.BigEndian.Uint64(src)
- b = permuteInitialBlock(b)
- left, right := uint32(b>>32), uint32(b)
- left = (left << 1) | (left >> 31)
- right = (right << 1) | (right >> 31)
- for i := 0; i < 8; i++ {
- left, right = feistel(left, right, c.cipher3.subkeys[15-2*i], c.cipher3.subkeys[15-(2*i+1)])
- }
- for i := 0; i < 8; i++ {
- right, left = feistel(right, left, c.cipher2.subkeys[2*i], c.cipher2.subkeys[2*i+1])
- }
- for i := 0; i < 8; i++ {
- left, right = feistel(left, right, c.cipher1.subkeys[15-2*i], c.cipher1.subkeys[15-(2*i+1)])
- }
- left = (left << 31) | (left >> 1)
- right = (right << 31) | (right >> 1)
- preOutput := (uint64(right) << 32) | uint64(left)
- binary.BigEndian.PutUint64(dst, permuteFinalBlock(preOutput))
- }
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