gtsocial-umbx

cipher.go (3536B)

---

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