lib/3rdParty/phpseclib/Crypt/DES.php

Properties

Description

Pure-PHP implementation of DES.

Uses mcrypt, if available, and an internal implementation, otherwise. PHP versions 4 and 5 Useful resources are as follows: - {@link http://en.wikipedia.org/wiki/DES_supplementary_material Wikipedia: DES supplementary material} - {@link http://www.itl.nist.gov/fipspubs/fip46-2.htm FIPS 46-2 - (DES), Data Encryption Standard} - {@link http://www.cs.eku.edu/faculty/styer/460/Encrypt/JS-DES.html JavaScript DES Example} Here's a short example of how to use this library: setKey('abcdefgh'); $size = 10 * 1024; $plaintext = ''; for ($i = 0; $i < $size; $i++) { $plaintext.= 'a'; } echo $des->decrypt($des->encrypt($plaintext)); ?> LICENSE: Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

Constants

  CRYPT_DES_ENCRYPT = 0

Contains array_reverse($keys[CRYPT_DES_DECRYPT])


  CRYPT_DES_DECRYPT = 1

Contains array_reverse($keys[CRYPT_DES_ENCRYPT])


  CRYPT_DES_MODE_CTR = -1

Encrypt / decrypt using the Counter mode.
Set to -1 since that's what Crypt/Random.php uses to index the CTR mode.

  CRYPT_DES_MODE_ECB = 1

Encrypt / decrypt using the Electronic Code Book mode.


  CRYPT_DES_MODE_CBC = 2

Encrypt / decrypt using the Code Book Chaining mode.


  CRYPT_DES_MODE_CFB = 3

Encrypt / decrypt using the Cipher Feedback mode.


  CRYPT_DES_MODE_OFB = 4

Encrypt / decrypt using the Cipher Feedback mode.


  CRYPT_DES_MODE_INTERNAL = 1

Toggles the internal implementation


  CRYPT_DES_MODE_MCRYPT = 2

Toggles the mcrypt implementation


  CRYPT_DES_MODE = CRYPT_DES_MODE_INTERNAL




Classes

Crypt_DES

Properties

 
 
public  
0.1.0  
No 
No 

Description

Pure-PHP implementation of DES.

Methods

Crypt_DES, _generate_xor, _pad, _prepareKey, _processBlock, _string_shift, _unpad, decrypt, disableContinuousBuffer, disablePadding, enableContinuousBuffer, enablePadding, encrypt, setIV, setKey,

Crypt_DES(   $mode = CRYPT_MODE_DES_CBC, ) : \Crypt_DES

Description

Default Constructor.
Determines whether or not the mcrypt extension should be used. $mode should only, at present, be CRYPT_DES_MODE_ECB or CRYPT_DES_MODE_CBC. If not explictly set, CRYPT_DES_MODE_CBC will be used.

Arguments

Name Type Description Default
$mode n/a CRYPT_MODE_DES_CBC

Return value

Type Description
\Crypt_DES

Tags

Name Description
access public

_generate_xor( Integer   $length, String   $iv, ) : n/a

Description

Generate CTR XOR encryption key
Encrypt the output of this and XOR it against the ciphertext / plaintext to get the plaintext / ciphertext in CTR mode.

Arguments

Name Type Description Default
$length Integer
$iv String

Return value

Type Description
n/a n/a

Tags

Name Description
see
see
access public

_pad(   $text, ) : n/a

Description

Pads a string
Pads a string using the RSA PKCS padding standards so that its length is a multiple of the blocksize (8). 8 - (strlen($text) & 7) bytes are added, each of which is equal to chr(8 - (strlen($text) & 7) If padding is disabled and $text is not a multiple of the blocksize, the string will be padded regardless and padding will, hence forth, be enabled.

Arguments

Name Type Description Default
$text n/a

Return value

Type Description
n/a n/a

Tags

Name Description
see
access private

_prepareKey( String   $key, ) : Array

Description

Creates the key schedule.

Arguments

Name Type Description Default
$key String

Return value

Type Description
Array

Tags

Name Description
access private

_processBlock( String   $block, Integer   $mode, ) : String

Description

Encrypts or decrypts a 64-bit block
$mode should be either CRYPT_DES_ENCRYPT or CRYPT_DES_DECRYPT. See {@link http://en.wikipedia.org/wiki/Image:Feistel.png Feistel.png} to get a general idea of what this function does.

Arguments

Name Type Description Default
$block String
$mode Integer

Return value

Type Description
String

Tags

Name Description
access private

_string_shift( String   $string,   $index = 1, ) : String

Description

String Shift
Inspired by array_shift

Arguments

Name Type Description Default
$string String
$index n/a 1

Return value

Type Description
String

Tags

Name Description
access private

_unpad(   $text, ) : n/a

Description

Unpads a string
If padding is enabled and the reported padding length is invalid the encryption key will be assumed to be wrong and false will be returned.

Arguments

Name Type Description Default
$text n/a

Return value

Type Description
n/a n/a

Tags

Name Description
see
access private

decrypt( String   $ciphertext, ) : n/a

Description

Decrypts a message.
If strlen($ciphertext) is not a multiple of 8, null bytes will be added to the end of the string until it is.

Arguments

Name Type Description Default
$ciphertext String

Return value

Type Description
n/a n/a

Tags

Name Description
see
access public

disableContinuousBuffer( ) : n/a

Description

Treat consecutive packets as if they are a discontinuous buffer.
The default behavior.

Return value

Type Description
n/a n/a

Tags

Name Description
see
access public

disablePadding( ) : n/a

Description

Do not pad packets.

Return value

Type Description
n/a n/a

Tags

Name Description
see
access public

enableContinuousBuffer( ) : n/a

Description

Treat consecutive "packets" as if they are a continuous buffer.
Say you have a 16-byte plaintext $plaintext. Using the default behavior, the two following code snippets will yield different outputs: echo $des->encrypt(substr($plaintext, 0, 8)); echo $des->encrypt(substr($plaintext, 8, 8)); echo $des->encrypt($plaintext); The solution is to enable the continuous buffer. Although this will resolve the above discrepancy, it creates another, as demonstrated with the following: $des->encrypt(substr($plaintext, 0, 8)); echo $des->decrypt($des->encrypt(substr($plaintext, 8, 8))); echo $des->decrypt($des->encrypt(substr($plaintext, 8, 8))); With the continuous buffer disabled, these would yield the same output. With it enabled, they yield different outputs. The reason is due to the fact that the initialization vector's change after every encryption / decryption round when the continuous buffer is enabled. When it's disabled, they remain constant. Put another way, when the continuous buffer is enabled, the state of the Crypt_DES() object changes after each encryption / decryption round, whereas otherwise, it'd remain constant. For this reason, it's recommended that continuous buffers not be used. They do offer better security and are, in fact, sometimes required (SSH uses them), however, they are also less intuitive and more likely to cause you problems.

Return value

Type Description
n/a n/a

Tags

Name Description
see
access public

enablePadding( ) : n/a

Description

Pad "packets".
DES works by encrypting eight bytes at a time. If you ever need to encrypt or decrypt something that's not a multiple of eight, it becomes necessary to pad the input so that it's length is a multiple of eight. Padding is enabled by default. Sometimes, however, it is undesirable to pad strings. Such is the case in SSH1, where "packets" are padded with random bytes before being encrypted. Unpad these packets and you risk stripping away characters that shouldn't be stripped away. (SSH knows how many bytes are added because the length is transmitted separately)

Return value

Type Description
n/a n/a

Tags

Name Description
see
access public

encrypt( String   $plaintext, ) : n/a

Description

Encrypts a message.
$plaintext will be padded with up to 8 additional bytes. Other DES implementations may or may not pad in the same manner. Other common approaches to padding and the reasons why it's necessary are discussed in the following URL: {@link http://www.di-mgt.com.au/cryptopad.html http://www.di-mgt.com.au/cryptopad.html} An alternative to padding is to, separately, send the length of the file. This is what SSH, in fact, does. strlen($plaintext) will still need to be a multiple of 8, however, arbitrary values can be added to make it that length.

Arguments

Name Type Description Default
$plaintext String

Return value

Type Description
n/a n/a

Tags

Name Description
see
access public

setIV( String   $iv, ) : n/a

Description

Sets the initialization vector. (optional)
SetIV is not required when CRYPT_DES_MODE_ECB is being used. If not explictly set, it'll be assumed to be all zero's.

Arguments

Name Type Description Default
$iv String

Return value

Type Description
n/a n/a

Tags

Name Description
access public

setKey( String   $key, ) : n/a

Description

Sets the key.
Keys can be of any length. DES, itself, uses 64-bit keys (eg. strlen($key) == 8), however, we only use the first eight, if $key has more then eight characters in it, and pad $key with the null byte if it is less then eight characters long. DES also requires that every eighth bit be a parity bit, however, we'll ignore that. If the key is not explicitly set, it'll be assumed to be all zero's.

Arguments

Name Type Description Default
$key String

Return value

Type Description
n/a n/a

Tags

Name Description
access public

Properties

$continuousBuffer, $debuffer, $dechanged, $decryptIV, $demcrypt, $ecb, $enbuffer, $enchanged, $encryptIV, $enmcrypt, $iv, $keys, $mode, $paddable, $padding,

Boolean  public  $continuousBuffer = false

Continuous Buffer status


String  public  $debuffer = ''

Decryption buffer for CTR, OFB and CFB modes


Boolean  public  $dechanged = true

Does the demcrypt resource need to be (re)initialized?


String  public  $decryptIV = "\0\0\0\0\0\0\0\0"

A "sliding" Initialization Vector


String  public  $demcrypt =

mcrypt resource for decryption
The mcrypt resource can be recreated every time something needs to be created or it can be created just once. Since mcrypt operates in continuous mode, by default, it'll need to be recreated when in non-continuous mode.

String  public  $ecb =

mcrypt resource for CFB mode


String  public  $enbuffer = ''

Encryption buffer for CTR, OFB and CFB modes


Boolean  public  $enchanged = true

Does the enmcrypt resource need to be (re)initialized?


String  public  $encryptIV = "\0\0\0\0\0\0\0\0"

A "sliding" Initialization Vector


String  public  $enmcrypt =

mcrypt resource for encryption
The mcrypt resource can be recreated every time something needs to be created or it can be created just once. Since mcrypt operates in continuous mode, by default, it'll need to be recreated when in non-continuous mode.

String  public  $iv = "\0\0\0\0\0\0\0\0"

The Initialization Vector


Array  public  $keys = "\0\0\0\0\0\0\0\0"

The Key Schedule


Integer  public  $mode =

The Encryption Mode


Boolean  public  $paddable = false

Is the mode one that is paddable?


Boolean  public  $padding = true

Padding status


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