mirror of
https://github.com/autc04/Retro68.git
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113 lines
3.0 KiB
Go
113 lines
3.0 KiB
Go
// Copyright 2011 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package des
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import (
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"crypto/cipher"
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"encoding/binary"
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"strconv"
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)
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// The DES block size in bytes.
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const BlockSize = 8
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type KeySizeError int
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func (k KeySizeError) Error() string {
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return "crypto/des: invalid key size " + strconv.Itoa(int(k))
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}
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// desCipher is an instance of DES encryption.
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type desCipher struct {
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subkeys [16]uint64
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}
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// NewCipher creates and returns a new cipher.Block.
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func NewCipher(key []byte) (cipher.Block, error) {
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if len(key) != 8 {
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return nil, KeySizeError(len(key))
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}
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c := new(desCipher)
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c.generateSubkeys(key)
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return c, nil
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}
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func (c *desCipher) BlockSize() int { return BlockSize }
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func (c *desCipher) Encrypt(dst, src []byte) { encryptBlock(c.subkeys[:], dst, src) }
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func (c *desCipher) Decrypt(dst, src []byte) { decryptBlock(c.subkeys[:], dst, src) }
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// A tripleDESCipher is an instance of TripleDES encryption.
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type tripleDESCipher struct {
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cipher1, cipher2, cipher3 desCipher
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}
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// NewTripleDESCipher creates and returns a new cipher.Block.
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func NewTripleDESCipher(key []byte) (cipher.Block, error) {
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if len(key) != 24 {
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return nil, KeySizeError(len(key))
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}
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c := new(tripleDESCipher)
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c.cipher1.generateSubkeys(key[:8])
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c.cipher2.generateSubkeys(key[8:16])
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c.cipher3.generateSubkeys(key[16:])
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return c, nil
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}
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func (c *tripleDESCipher) BlockSize() int { return BlockSize }
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func (c *tripleDESCipher) Encrypt(dst, src []byte) {
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b := binary.BigEndian.Uint64(src)
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b = permuteInitialBlock(b)
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left, right := uint32(b>>32), uint32(b)
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left = (left << 1) | (left >> 31)
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right = (right << 1) | (right >> 31)
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for i := 0; i < 8; i++ {
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left, right = feistel(left, right, c.cipher1.subkeys[2*i], c.cipher1.subkeys[2*i+1])
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}
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for i := 0; i < 8; i++ {
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right, left = feistel(right, left, c.cipher2.subkeys[15-2*i], c.cipher2.subkeys[15-(2*i+1)])
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}
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for i := 0; i < 8; i++ {
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left, right = feistel(left, right, c.cipher3.subkeys[2*i], c.cipher3.subkeys[2*i+1])
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}
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left = (left << 31) | (left >> 1)
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right = (right << 31) | (right >> 1)
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preOutput := (uint64(right) << 32) | uint64(left)
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binary.BigEndian.PutUint64(dst, permuteFinalBlock(preOutput))
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}
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func (c *tripleDESCipher) Decrypt(dst, src []byte) {
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b := binary.BigEndian.Uint64(src)
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b = permuteInitialBlock(b)
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left, right := uint32(b>>32), uint32(b)
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left = (left << 1) | (left >> 31)
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right = (right << 1) | (right >> 31)
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for i := 0; i < 8; i++ {
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left, right = feistel(left, right, c.cipher3.subkeys[15-2*i], c.cipher3.subkeys[15-(2*i+1)])
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}
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for i := 0; i < 8; i++ {
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right, left = feistel(right, left, c.cipher2.subkeys[2*i], c.cipher2.subkeys[2*i+1])
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}
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for i := 0; i < 8; i++ {
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left, right = feistel(left, right, c.cipher1.subkeys[15-2*i], c.cipher1.subkeys[15-(2*i+1)])
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}
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left = (left << 31) | (left >> 1)
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right = (right << 31) | (right >> 1)
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preOutput := (uint64(right) << 32) | uint64(left)
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binary.BigEndian.PutUint64(dst, permuteFinalBlock(preOutput))
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}
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