100 строки
3.4 KiB
Go
100 строки
3.4 KiB
Go
// Copyright 2010 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 blowfish implements Bruce Schneier's Blowfish encryption algorithm.
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//
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// Blowfish is a legacy cipher and its short block size makes it vulnerable to
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// birthday bound attacks (see https://sweet32.info). It should only be used
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// where compatibility with legacy systems, not security, is the goal.
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//
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// Deprecated: any new system should use AES (from crypto/aes, if necessary in
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// an AEAD mode like crypto/cipher.NewGCM) or XChaCha20-Poly1305 (from
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// golang.org/x/crypto/chacha20poly1305).
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package blowfish
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// The code is a port of Bruce Schneier's C implementation.
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// See https://www.schneier.com/blowfish.html.
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import "strconv"
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// The Blowfish block size in bytes.
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const BlockSize = 8
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// A Cipher is an instance of Blowfish encryption using a particular key.
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type Cipher struct {
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p [18]uint32
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s0, s1, s2, s3 [256]uint32
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}
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type KeySizeError int
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func (k KeySizeError) Error() string {
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return "crypto/blowfish: invalid key size " + strconv.Itoa(int(k))
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}
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// NewCipher creates and returns a Cipher.
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// The key argument should be the Blowfish key, from 1 to 56 bytes.
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func NewCipher(key []byte) (*Cipher, error) {
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var result Cipher
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if k := len(key); k < 1 || k > 56 {
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return nil, KeySizeError(k)
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}
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initCipher(&result)
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ExpandKey(key, &result)
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return &result, nil
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}
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// NewSaltedCipher creates a returns a Cipher that folds a salt into its key
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// schedule. For most purposes, NewCipher, instead of NewSaltedCipher, is
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// sufficient and desirable. For bcrypt compatibility, the key can be over 56
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// bytes.
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func NewSaltedCipher(key, salt []byte) (*Cipher, error) {
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if len(salt) == 0 {
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return NewCipher(key)
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}
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var result Cipher
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if k := len(key); k < 1 {
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return nil, KeySizeError(k)
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}
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initCipher(&result)
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expandKeyWithSalt(key, salt, &result)
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return &result, nil
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}
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// BlockSize returns the Blowfish block size, 8 bytes.
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// It is necessary to satisfy the Block interface in the
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// package "crypto/cipher".
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func (c *Cipher) BlockSize() int { return BlockSize }
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// Encrypt encrypts the 8-byte buffer src using the key k
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// and stores the result in dst.
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// Note that for amounts of data larger than a block,
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// it is not safe to just call Encrypt on successive blocks;
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// instead, use an encryption mode like CBC (see crypto/cipher/cbc.go).
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func (c *Cipher) Encrypt(dst, src []byte) {
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l := uint32(src[0])<<24 | uint32(src[1])<<16 | uint32(src[2])<<8 | uint32(src[3])
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r := uint32(src[4])<<24 | uint32(src[5])<<16 | uint32(src[6])<<8 | uint32(src[7])
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l, r = encryptBlock(l, r, c)
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dst[0], dst[1], dst[2], dst[3] = byte(l>>24), byte(l>>16), byte(l>>8), byte(l)
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dst[4], dst[5], dst[6], dst[7] = byte(r>>24), byte(r>>16), byte(r>>8), byte(r)
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}
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// Decrypt decrypts the 8-byte buffer src using the key k
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// and stores the result in dst.
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func (c *Cipher) Decrypt(dst, src []byte) {
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l := uint32(src[0])<<24 | uint32(src[1])<<16 | uint32(src[2])<<8 | uint32(src[3])
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r := uint32(src[4])<<24 | uint32(src[5])<<16 | uint32(src[6])<<8 | uint32(src[7])
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l, r = decryptBlock(l, r, c)
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dst[0], dst[1], dst[2], dst[3] = byte(l>>24), byte(l>>16), byte(l>>8), byte(l)
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dst[4], dst[5], dst[6], dst[7] = byte(r>>24), byte(r>>16), byte(r>>8), byte(r)
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}
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func initCipher(c *Cipher) {
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copy(c.p[0:], p[0:])
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copy(c.s0[0:], s0[0:])
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copy(c.s1[0:], s1[0:])
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copy(c.s2[0:], s2[0:])
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copy(c.s3[0:], s3[0:])
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}
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