Source file src/pkg/crypto/des/cipher.go
1 // Copyright 2011 The Go Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style 3 // license that can be found in the LICENSE file. 4 5 package des 6 7 import ( 8 "crypto/cipher" 9 "strconv" 10 ) 11 12 // The DES block size in bytes. 13 const BlockSize = 8 14 15 type KeySizeError int 16 17 func (k KeySizeError) Error() string { 18 return "crypto/des: invalid key size " + strconv.Itoa(int(k)) 19 } 20 21 // desCipher is an instance of DES encryption. 22 type desCipher struct { 23 subkeys [16]uint64 24 } 25 26 // NewCipher creates and returns a new cipher.Block. 27 func NewCipher(key []byte) (cipher.Block, error) { 28 if len(key) != 8 { 29 return nil, KeySizeError(len(key)) 30 } 31 32 c := new(desCipher) 33 c.generateSubkeys(key) 34 return c, nil 35 } 36 37 func (c *desCipher) BlockSize() int { return BlockSize } 38 39 func (c *desCipher) Encrypt(dst, src []byte) { encryptBlock(c.subkeys[:], dst, src) } 40 41 func (c *desCipher) Decrypt(dst, src []byte) { decryptBlock(c.subkeys[:], dst, src) } 42 43 // A tripleDESCipher is an instance of TripleDES encryption. 44 type tripleDESCipher struct { 45 cipher1, cipher2, cipher3 desCipher 46 } 47 48 // NewTripleDESCipher creates and returns a new cipher.Block. 49 func NewTripleDESCipher(key []byte) (cipher.Block, error) { 50 if len(key) != 24 { 51 return nil, KeySizeError(len(key)) 52 } 53 54 c := new(tripleDESCipher) 55 c.cipher1.generateSubkeys(key[:8]) 56 c.cipher2.generateSubkeys(key[8:16]) 57 c.cipher3.generateSubkeys(key[16:]) 58 return c, nil 59 } 60 61 func (c *tripleDESCipher) BlockSize() int { return BlockSize } 62 63 func (c *tripleDESCipher) Encrypt(dst, src []byte) { 64 c.cipher1.Encrypt(dst, src) 65 c.cipher2.Decrypt(dst, dst) 66 c.cipher3.Encrypt(dst, dst) 67 } 68 69 func (c *tripleDESCipher) Decrypt(dst, src []byte) { 70 c.cipher3.Decrypt(dst, src) 71 c.cipher2.Encrypt(dst, dst) 72 c.cipher1.Decrypt(dst, dst) 73 }