RC4

Pure-PHP implementation of RC4.

Full name: \phpseclib\Crypt\RC4
Parent class: \phpseclib\Crypt\Base

Constants

Constant	Visibility	Type	Value
`ENCRYPT`	public		0
`DECRYPT`	public		1

Properties

block_size

Block Length of the cipher

public int $block_size

RC4 is a stream cipher so we the block_size to 0

See Also:

\phpseclib\Crypt\Base::block_size -

key_length

Key Length (in bytes)

public int $key_length

See Also:

\phpseclib\Crypt\RC4::setKeyLength() -

cipher_name_mcrypt

The mcrypt specific name of the cipher

public string $cipher_name_mcrypt

See Also:

\phpseclib\Crypt\Base::cipher_name_mcrypt -

use_inline_crypt

Holds whether performance-optimized $inline_crypt() can/should be used.

public mixed $use_inline_crypt

See Also:

\phpseclib\Crypt\Base::inline_crypt -

key

The Key

public string $key

See Also:

\phpseclib\Crypt\self::setKey() -

stream

The Key Stream for decryption and encryption

public array $stream

See Also:

\phpseclib\Crypt\self::setKey() -

Methods

__construct

Default Constructor.

public __construct(): \phpseclib\Crypt\RC4

Determines whether or not the mcrypt extension should be used.

See Also:

\phpseclib\Crypt\Base::__construct() -

isValidEngine

Test for engine validity

public isValidEngine(int $engine): bool

This is mainly just a wrapper to set things up for \phpseclib\Crypt\Base::isValidEngine()

Parameters:

Parameter	Type	Description
`$engine`	int

See Also:

\phpseclib\Crypt\Base::__construct() -

setIV

Dummy function.

public setIV(string $iv): mixed

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} 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} {@link http://en.wikipedia.org/wiki/Related_key_attack}

Parameters:

Parameter	Type	Description
`$iv`	string

See Also:

\phpseclib\Crypt\self::setKey() -

setKeyLength

Sets the key length

public setKeyLength(int $length): mixed

Keys can be between 1 and 256 bytes long.

Parameters:

Parameter	Type	Description
`$length`	int

encrypt

Encrypts a message.

public encrypt(string $plaintext): string

Parameters:

Parameter	Type	Description
`$plaintext`	string

Return Value:

$ciphertext

See Also:

\phpseclib\Crypt\Base::decrypt() - * \phpseclib\Crypt\self::_crypt() -

decrypt

Decrypts a message.

public decrypt(string $ciphertext): string

$this->decrypt($this->encrypt($plaintext)) == $this->encrypt($this->encrypt($plaintext)). At least if the continuous buffer is disabled.

Parameters:

Parameter	Type	Description
`$ciphertext`	string

Return Value:

$plaintext

See Also:

\phpseclib\Crypt\Base::encrypt() - * \phpseclib\Crypt\self::_crypt() -

_encryptBlock

Encrypts a block

public _encryptBlock(string $in): string

Parameters:

Parameter	Type	Description
`$in`	string

_decryptBlock

Decrypts a block

public _decryptBlock(string $in): string

Parameters:

Parameter	Type	Description
`$in`	string

_setupKey

Setup the key (expansion)

public _setupKey(): mixed

See Also:

\phpseclib\Crypt\Base::_setupKey() -

_crypt

Encrypts or decrypts a message.

public _crypt(string $text, int $mode): string

Parameters:

Parameter	Type	Description
`$text`	string
`$mode`	int

Return Value:

$text

See Also:

\phpseclib\Crypt\self::encrypt() - * \phpseclib\Crypt\self::decrypt() -

Inherited methods

__construct

Default Constructor.

public __construct(int $mode = self::MODE_CBC): mixed

Determines whether or not the mcrypt extension should be used.

$mode could be:

self::MODE_ECB
self::MODE_CBC
self::MODE_CTR
self::MODE_CFB
self::MODE_OFB

If not explicitly set, self::MODE_CBC will be used.

Parameters:

Parameter	Type	Description
`$mode`	int

setKeyLength

Sets the key length.

public setKeyLength(int $length): mixed

Keys with explicitly set lengths need to be treated accordingly

Parameters:

Parameter	Type	Description
`$length`	int

getKeyLength

Returns the current key length in bits

public getKeyLength(): int

getBlockLength

Returns the current block length in bits

public getBlockLength(): int

_openssl_ctr_process

OpenSSL CTR Processor

public _openssl_ctr_process(string $plaintext, string& $encryptIV, array& $buffer): string

PHP's OpenSSL bindings do not operate in continuous mode so we'll wrap around it. Since the keystream for CTR is the same for both encrypting and decrypting this function is re-used by both Base::encrypt() and Base::decrypt(). Also, OpenSSL doesn't implement CTR for all of it's symmetric ciphers so this function will emulate CTR with ECB when necessary.

Parameters:

Parameter	Type	Description
`$plaintext`	string
`$encryptIV`	string
`$buffer`	array

See Also:

\phpseclib\Crypt\self::encrypt() - * \phpseclib\Crypt\self::decrypt() -

_openssl_ofb_process

OpenSSL OFB Processor

public _openssl_ofb_process(string $plaintext, string& $encryptIV, array& $buffer): string

PHP's OpenSSL bindings do not operate in continuous mode so we'll wrap around it. Since the keystream for OFB is the same for both encrypting and decrypting this function is re-used by both Base::encrypt() and Base::decrypt().

Parameters:

Parameter	Type	Description
`$plaintext`	string
`$encryptIV`	string
`$buffer`	array

See Also:

\phpseclib\Crypt\self::encrypt() - * \phpseclib\Crypt\self::decrypt() -

_openssl_translate_mode

phpseclib <-> OpenSSL Mode Mapper

public _openssl_translate_mode(): int

May need to be overwritten by classes extending this one in some cases

enablePadding

Pad "packets".

public enablePadding(): mixed

Block ciphers working by encrypting between their specified [$this->]block_size at a time If you ever need to encrypt or decrypt something that isn't of the proper length, it becomes necessary to pad the input so that it is of the proper length.

Padding is enabled by default. Sometimes, however, it is undesirable to pad strings. Such is the case in SSH, 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)

See Also:

\phpseclib\Crypt\self::disablePadding() -

disablePadding

Do not pad packets.

public disablePadding(): mixed

See Also:

\phpseclib\Crypt\self::enablePadding() -

isValidEngine

Test for engine validity

public isValidEngine(int $engine): bool

Parameters:

Parameter	Type	Description
`$engine`	int

See Also:

\phpseclib\Crypt\self::__construct() -

setPreferredEngine

Sets the preferred crypt engine

public setPreferredEngine(int $engine): mixed

Currently, $engine could be:

\phpseclib\Crypt\Base::ENGINE_OPENSSL [very fast]
\phpseclib\Crypt\Base::ENGINE_MCRYPT [fast]
\phpseclib\Crypt\Base::ENGINE_INTERNAL [slow]

If the preferred crypt engine is not available the fastest available one will be used

Parameters:

Parameter	Type	Description
`$engine`	int

See Also:

\phpseclib\Crypt\self::__construct() -

getEngine

Returns the engine currently being utilized

public getEngine(): mixed

See Also:

\phpseclib\Crypt\self::_setEngine() -

_setEngine

Sets the engine as appropriate

public _setEngine(): mixed

See Also:

\phpseclib\Crypt\self::__construct() -

_encryptBlock

Encrypts a block

public _encryptBlock(string $in): string

Note: Must be extended by the child \phpseclib\Crypt* class

This method is abstract.

Parameters:

Parameter	Type	Description
`$in`	string

_decryptBlock

Decrypts a block

public _decryptBlock(string $in): string

Note: Must be extended by the child \phpseclib\Crypt* class

This method is abstract.

Parameters:

Parameter	Type	Description
`$in`	string

_setupKey

Setup the key (expansion)

public _setupKey(): mixed

Only used if $engine == self::ENGINE_INTERNAL

Note: Must extend by the child \phpseclib\Crypt* class

This method is abstract.

See Also:

\phpseclib\Crypt\self::_setup() -

_pad

Pads a string

public _pad(string $text): string

Pads a string using the RSA PKCS padding standards so that its length is a multiple of the blocksize. $this->block_size - (strlen($text) % $this->block_size) bytes are added, each of which is equal to chr($this->block_size - (strlen($text) % $this->block_size)

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.

Parameters:

Parameter	Type	Description
`$text`	string

See Also:

\phpseclib\Crypt\self::_unpad() -

_unpad

Unpads a string.

public _unpad(string $text): 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.

Parameters:

Parameter	Type	Description
`$text`	string

See Also:

\phpseclib\Crypt\self::_pad() -

_string_shift

String Shift

public _string_shift(string& $string, int $index = 1): string

Inspired by array_shift

Parameters:

Parameter	Type	Description
`$string`	string
`$index`	int

_string_pop

String Pop

public _string_pop(string& $string, int $index = 1): string

Inspired by array_pop

Parameters:

Parameter	Type	Description
`$string`	string
`$index`	int

_increment_str

Increment the current string

public _increment_str(string& $var): mixed

Parameters:

Parameter	Type	Description
`$var`	string

See Also:

\phpseclib\Crypt\self::decrypt() - * \phpseclib\Crypt\self::encrypt() -

_createInlineCryptFunction

Creates the performance-optimized function for en/decrypt()

public _createInlineCryptFunction(array $cipher_code): string

Internally for phpseclib developers:

_createInlineCryptFunction():

merge the $cipher_code [setup'ed by _setupInlineCrypt()] with the current [$this->]mode of operation code
create the $inline function, which called by encrypt() / decrypt() as its replacement to speed up the en/decryption operations.
return the name of the created $inline callback function
used to speed up en/decryption

The main reason why can speed up things [up to 50%] this way are:

using variables more effective then regular. (ie no use of expensive arrays but integers $k_0, $k_1 ... or even, for example, the pure $key[] values hardcoded)
avoiding 1000's of function calls of ie _encryptBlock() but inlining the crypt operations. in the mode of operation for() loop.
full loop unroll the (sometimes key-dependent) rounds avoiding this way ++$i counters and runtime-if's etc...

The basic code architectur of the generated $inline en/decrypt() lambda function, in pseudo php, is:

+----------------------------------------------------------------------------------------------+ | callback $inline = create_function: | | lambda_function_0001_crypt_ECB($action, $text) | | { | | INSERT PHP CODE OF: | | $cipher_code['init_crypt']; // general init code. | | // ie: $sbox'es declarations used for | | // encrypt and decrypt'ing. | | | | switch ($action) { | | case 'encrypt': | | INSERT PHP CODE OF: | | $cipher_code['init_encrypt']; // encrypt sepcific init code. | | ie: specified $key or $box | | declarations for encrypt'ing. | | | | foreach ($ciphertext) { | | $in = $block_size of $ciphertext; | | | | INSERT PHP CODE OF: | | $cipher_code['encrypt_block']; // encrypt's (string) $in, which is always: | | // strlen($in) == $this->block_size | | // here comes the cipher algorithm in action | | // for encryption. | | // $cipher_code['encrypt_block'] has to | | // encrypt the content of the $in variable | | | | $plaintext .= $in; | | } | | return $plaintext; | | | | case 'decrypt': | | INSERT PHP CODE OF: | | $cipher_code['init_decrypt']; // decrypt sepcific init code | | ie: specified $key or $box | | declarations for decrypt'ing. | | foreach ($plaintext) { | | $in = $block_size of $plaintext; | | | | INSERT PHP CODE OF: | | $cipher_code['decrypt_block']; // decrypt's (string) $in, which is always | | // strlen($in) == $this->block_size | | // here comes the cipher algorithm in action | | // for decryption. | | // $cipher_code['decrypt_block'] has to | | // decrypt the content of the $in variable | | $ciphertext .= $in; | | } | | return $ciphertext; | | } | | } | +----------------------------------------------------------------------------------------------+

See also the \phpseclib\Crypt*::_setupInlineCrypt()'s for productive inline $cipher_code's how they works.

Structure of: $cipher_code = array( 'init_crypt' => (string) '', // optional 'init_encrypt' => (string) '', // optional 'init_decrypt' => (string) '', // optional 'encrypt_block' => (string) '', // required 'decrypt_block' => (string) '' // required );

Parameters:

Parameter	Type	Description
`$cipher_code`	array

Return Value:

(the name of the created callback function)

See Also:

\phpseclib\Crypt\self::_setupInlineCrypt() - * \phpseclib\Crypt\self::encrypt() - * \phpseclib\Crypt\self::decrypt() -

_getLambdaFunctions

Holds the lambda_functions table (classwide)

public _getLambdaFunctions(): array

Each name of the lambda function, created from _setupInlineCrypt() && _createInlineCryptFunction() is stored, classwide (!), here for reusing.

The string-based index of $function is a classwide unique value representing, at least, the $mode of operation (or more... depends of the optimizing level) for which $mode the lambda function was created.

Return Value:

&$functions

_hashInlineCryptFunction

Generates a digest from $bytes

public _hashInlineCryptFunction(string $bytes): string

Parameters:

Parameter	Type	Description
`$bytes`	string

See Also:

\phpseclib\Crypt\self::_setupInlineCrypt() -

safe_intval

Convert float to int

public safe_intval(string $x): int

On ARM CPUs converting floats to ints doesn't always work

Parameters:

Parameter	Type	Description
`$x`	string

safe_intval_inline

eval()'able string for in-line float to int

public safe_intval_inline(): string

do_nothing

Dummy error handler to suppress mcrypt errors

public do_nothing(): mixed

continuousBufferEnabled

Is the continuous buffer enabled?

public continuousBufferEnabled(): bool

Automatically generated on 2025-03-18