vendor/golang.org/x/crypto/blowfish/cipher.go

   1 // Copyright 2010 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 blowfish implements Bruce Schneier's Blowfish encryption algorithm.
   6 //
   7 // Blowfish is a legacy cipher and its short block size makes it vulnerable to
   8 // birthday bound attacks (see https://sweet32.info). It should only be used
   9 // where compatibility with legacy systems, not security, is the goal.
  10 //
  11 // Deprecated: any new system should use AES (from crypto/aes, if necessary in
  12 // an AEAD mode like crypto/cipher.NewGCM) or XChaCha20-Poly1305 (from
  13 // golang.org/x/crypto/chacha20poly1305).
  14 package blowfish // import "golang.org/x/crypto/blowfish"
  15
  16 // The code is a port of Bruce Schneier's C implementation.
  17 // See https://www.schneier.com/blowfish.html.
  18
  19 import "strconv"
  20
  21 // The Blowfish block size in bytes.
  22 const BlockSize = 8
  23
  24 // A Cipher is an instance of Blowfish encryption using a particular key.
  25 type Cipher struct {
  26         p              [18]uint32
  27         s0, s1, s2, s3 [256]uint32
  28 }
  29
  30 type KeySizeError int
  31
  32 func (k KeySizeError) Error() string {
  33         return "crypto/blowfish: invalid key size " + strconv.Itoa(int(k))
  34 }
  35
  36 // NewCipher creates and returns a Cipher.
  37 // The key argument should be the Blowfish key, from 1 to 56 bytes.
  38 func NewCipher(key []byte) (*Cipher, error) {
  39         var result Cipher
  40         if k := len(key); k < 1 || k > 56 {
  41                 return nil, KeySizeError(k)
  42         }
  43         initCipher(&result)
  44         ExpandKey(key, &result)
  45         return &result, nil
  46 }
  47
  48 // NewSaltedCipher creates a returns a Cipher that folds a salt into its key
  49 // schedule. For most purposes, NewCipher, instead of NewSaltedCipher, is
  50 // sufficient and desirable. For bcrypt compatibility, the key can be over 56
  51 // bytes.
  52 func NewSaltedCipher(key, salt []byte) (*Cipher, error) {
  53         if len(salt) == 0 {
  54                 return NewCipher(key)
  55         }
  56         var result Cipher
  57         if k := len(key); k < 1 {
  58                 return nil, KeySizeError(k)
  59         }
  60         initCipher(&result)
  61         expandKeyWithSalt(key, salt, &result)
  62         return &result, nil
  63 }
  64
  65 // BlockSize returns the Blowfish block size, 8 bytes.
  66 // It is necessary to satisfy the Block interface in the
  67 // package "crypto/cipher".
  68 func (c *Cipher) BlockSize() int { return BlockSize }
  69
  70 // Encrypt encrypts the 8-byte buffer src using the key k
  71 // and stores the result in dst.
  72 // Note that for amounts of data larger than a block,
  73 // it is not safe to just call Encrypt on successive blocks;
  74 // instead, use an encryption mode like CBC (see crypto/cipher/cbc.go).
  75 func (c *Cipher) Encrypt(dst, src []byte) {
  76         l := uint32(src[0])<<24 | uint32(src[1])<<16 | uint32(src[2])<<8 | uint32(src[3])
  77         r := uint32(src[4])<<24 | uint32(src[5])<<16 | uint32(src[6])<<8 | uint32(src[7])
  78         l, r = encryptBlock(l, r, c)
  79         dst[0], dst[1], dst[2], dst[3] = byte(l>>24), byte(l>>16), byte(l>>8), byte(l)
  80         dst[4], dst[5], dst[6], dst[7] = byte(r>>24), byte(r>>16), byte(r>>8), byte(r)
  81 }
  82
  83 // Decrypt decrypts the 8-byte buffer src using the key k
  84 // and stores the result in dst.
  85 func (c *Cipher) Decrypt(dst, src []byte) {
  86         l := uint32(src[0])<<24 | uint32(src[1])<<16 | uint32(src[2])<<8 | uint32(src[3])
  87         r := uint32(src[4])<<24 | uint32(src[5])<<16 | uint32(src[6])<<8 | uint32(src[7])
  88         l, r = decryptBlock(l, r, c)
  89         dst[0], dst[1], dst[2], dst[3] = byte(l>>24), byte(l>>16), byte(l>>8), byte(l)
  90         dst[4], dst[5], dst[6], dst[7] = byte(r>>24), byte(r>>16), byte(r>>8), byte(r)
  91 }
  92
  93 func initCipher(c *Cipher) {
  94         copy(c.p[0:], p[0:])
  95         copy(c.s0[0:], s0[0:])
  96         copy(c.s1[0:], s1[0:])
  97         copy(c.s2[0:], s2[0:])
  98         copy(c.s3[0:], s3[0:])
  99 }