lib/3rdParty/phpseclib/Crypt/RC4.php

Properties

Description

Pure-PHP implementation of RC4.

Uses mcrypt, if available, and an internal implementation, otherwise. PHP versions 4 and 5 Useful resources are as follows: - {@link http://www.mozilla.org/projects/security/pki/nss/draft-kaukonen-cipher-arcfour-03.txt ARCFOUR Algorithm} - {@link http://en.wikipedia.org/wiki/RC4 - Wikipedia: RC4} RC4 is also known as ARCFOUR or ARC4. The reason is elaborated upon at Wikipedia. This class is named RC4 and not ARCFOUR or ARC4 because RC4 is how it is refered to in the SSH1 specification. 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 $rc4->decrypt($rc4->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_RC4_MODE_INTERNAL = 1

Toggles the internal implementation


  CRYPT_RC4_MODE_MCRYPT = 2

Toggles the mcrypt implementation


  CRYPT_RC4_ENCRYPT = 0




  CRYPT_RC4_DECRYPT = 1




  CRYPT_RC4_MODE = CRYPT_RC4_MODE_INTERNAL




Classes

Crypt_RC4

Properties

 
 
public  
 
No 
No 

Description

Pure-PHP implementation of RC4.

Methods

Crypt_RC4, __destruct, _closeMCrypt, _crypt, decrypt, disableContinuousBuffer, disablePadding, enableContinuousBuffer, enablePadding, encrypt, setIV, setKey, setMCrypt,

Crypt_RC4( ) : \Crypt_RC4

Description

Default Constructor.
Determines whether or not the mcrypt extension should be used.

Return value

Type Description
\Crypt_RC4

Tags

Name Description
access public

__destruct( ) : n/a

Description

Class destructor.
Will be called, automatically, if you're using PHP5. If you're using PHP4, call it yourself. Only really needs to be called if mcrypt is being used.

Return value

Type Description
n/a n/a

Tags

Name Description
access public

_closeMCrypt( ) : n/a

Description

Properly close the MCrypt objects.

Return value

Type Description
n/a n/a

Tags

Name Description
access prviate

_crypt( String   $text, Integer   $mode, ) : n/a

Description

Encrypts or decrypts a message.

Arguments

Name Type Description Default
$text String
$mode Integer

Return value

Type Description
n/a n/a

Tags

Name Description
see
see
access private

decrypt( String   $ciphertext, ) : n/a

Description

Decrypts a message.
$this->decrypt($this->encrypt($plaintext)) == $this->encrypt($this->encrypt($plaintext)). Atleast if the continuous buffer is disabled.

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

Dummy function.

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 $rc4->encrypt(substr($plaintext, 0, 8)); echo $rc4->encrypt(substr($plaintext, 8, 8)); echo $rc4->encrypt($plaintext); The solution is to enable the continuous buffer. Although this will resolve the above discrepancy, it creates another, as demonstrated with the following: $rc4->encrypt(substr($plaintext, 0, 8)); echo $rc4->decrypt($des->encrypt(substr($plaintext, 8, 8))); echo $rc4->decrypt($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

Dummy function.
Since RC4 is a stream cipher and not a block cipher, no padding is necessary. The only reason this function is included is so that you can switch between a block cipher and a stream cipher transparently.

Return value

Type Description
n/a n/a

Tags

Name Description
see
access public

encrypt( String   $plaintext, ) : n/a

Description

Encrypts a message.

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

Dummy function.
Some protocols, such as WEP, prepend an "initialization vector" to the key, effectively creating a new key [1]. If you need to use an initialization vector in this manner, feel free to prepend it to the key, yourself, before calling setKey(). [1] WEP's initialization vectors (IV's) are used in a somewhat insecure way. Since, in that protocol, the IV's are relatively easy to predict, an attack described by {@link http://www.drizzle.com/~aboba/IEEE/rc4_ksaproc.pdf Scott Fluhrer, Itsik Mantin, and Adi Shamir} can be used to quickly guess at the rest of the key. The following links elaborate: {@link http://www.rsa.com/rsalabs/node.asp?id=2009 http://www.rsa.com/rsalabs/node.asp?id=2009} {@link http://en.wikipedia.org/wiki/Related_key_attack http://en.wikipedia.org/wiki/Related_key_attack}

Arguments

Name Type Description Default
$iv String

Return value

Type Description
n/a n/a

Tags

Name Description
see
access public

setKey( String   $key, ) : n/a

Description

Sets the key.
Keys can be between 1 and 256 bytes long. If they are longer then 256 bytes, the first 256 bytes will be used. If no key is explicitly set, it'll be assumed to be a single null byte.

Arguments

Name Type Description Default
$key String

Return value

Type Description
n/a n/a

Tags

Name Description
access public

setMCrypt(   $algorithm_directory = '',   $mode_directory = '', ) : n/a

Description

Sets MCrypt parameters. (optional)
If MCrypt is being used, empty strings will be used, unless otherwise specified.

Arguments

Name Type Description Default
$algorithm_directory n/a ''
$mode_directory n/a ''

Return value

Type Description
n/a n/a

Tags

Name Description
link http://php.net/function.mcrypt-module-open#function.mcrypt-module-open
access public

Properties

$continuousBuffer, $decryptIndex, $decryptStream, $encryptIndex, $encryptStream, $key, $mcrypt, $mode,

Boolean  public  $continuousBuffer = false

Continuous Buffer status


Integer  public  $decryptIndex = 0

The $i and $j indexes for decryption


Array  public  $decryptStream = false

The Key Stream for decryption
If CRYPT_RC4_MODE == CRYPT_RC4_MODE_MCRYPT, this will be equal to the mcrypt object

Integer  public  $encryptIndex = 0

The $i and $j indexes for encryption


Array  public  $encryptStream = false

The Key Stream for encryption
If CRYPT_RC4_MODE == CRYPT_RC4_MODE_MCRYPT, this will be equal to the mcrypt object

String  public  $key = "\0"

The Key


Array  public  $mcrypt = array('', '')

MCrypt parameters


Integer  public  $mode =

The Encryption Algorithm
Only used if CRYPT_RC4_MODE == CRYPT_RC4_MODE_MCRYPT. Only possible values are MCRYPT_RC4 or MCRYPT_ARCFOUR.

Documentation was generated by phpDocumentor 2.0.1 .

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