mirror of
https://github.com/danog/tgseclib.git
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542 lines
14 KiB
PHP
542 lines
14 KiB
PHP
<?php
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/**
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* Pure-PHP implementation of Salsa20.
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*
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* PHP version 5
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*
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* @category Crypt
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* @package Salsa20
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* @author Jim Wigginton <terrafrost@php.net>
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* @copyright 2019 Jim Wigginton
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* @license http://www.opensource.org/licenses/mit-license.html MIT License
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* @link http://phpseclib.sourceforge.net
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*/
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namespace phpseclib\Crypt;
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use phpseclib\Crypt\Common\StreamCipher;
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use phpseclib\Exception\InsufficientSetupException;
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use phpseclib\Exception\BadDecryptionException;
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use phpseclib\Common\Functions\Strings;
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/**
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* Pure-PHP implementation of Salsa20.
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*
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* @package Salsa20
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* @author Jim Wigginton <terrafrost@php.net>
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* @access public
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*/
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class Salsa20 extends StreamCipher
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{
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/**
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* Part 1 of the state
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*
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* @var string|false
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*/
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protected $p1 = false;
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/**
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* Part 2 of the state
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*
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* @var string|false
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*/
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protected $p2 = false;
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/**
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* Key Length (in bytes)
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*
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* @var int
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*/
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protected $key_length = 32; // = 256 bits
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/**
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* Block Length of the cipher
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*
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* Salsa20 is a stream cipher
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* so we the block_size to 0
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*
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* @var int
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*/
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protected $block_size = 0;
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/**#@+
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* @access private
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* @see \phpseclib\Crypt\Salsa20::crypt()
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*/
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const ENCRYPT = 0;
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const DECRYPT = 1;
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/**#@-*/
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/**
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* Encryption buffer for continuous mode
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*
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* @var array
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*/
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protected $enbuffer;
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/**
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* Decryption buffer for continuous mode
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*
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* @var array
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*/
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protected $debuffer;
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/**
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* Counter
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*
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* @var int
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*/
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protected $counter = 0;
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/**
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* Using Generated Poly1305 Key
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*
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* @var boolean
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*/
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protected $usingGeneratedPoly1305Key = false;
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/**
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* Default Constructor.
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*
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* @see \phpseclib\Crypt\Common\SymmetricKey::__construct()
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* @return \phpseclib\Crypt\Salsa20
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*/
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public function __construct()
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{
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parent::__construct('stream');
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}
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/**
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* Salsa20 does not use an IV
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*
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* @return bool
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*/
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public function usesIV()
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{
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return false;
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}
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/**
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* Salsa20 uses a nonce
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*
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* @return bool
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*/
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public function usesNonce()
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{
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return true;
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}
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/**
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* Sets the key.
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*
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* @param string $key
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* @throws \LengthException if the key length isn't supported
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*/
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public function setKey($key)
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{
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switch (strlen($key)) {
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case 16:
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case 32:
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break;
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default:
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throw new \LengthException('Key of size ' . strlen($key) . ' not supported by this algorithm. Only keys of sizes 16 or 32 are supported');
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}
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parent::setKey($key);
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}
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/**
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* Sets the nonce.
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*
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* @param string $nonce
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*/
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public function setNonce($nonce)
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{
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if (strlen($nonce) != 8) {
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throw new \LengthException('Nonce of size ' . strlen($key) . ' not supported by this algorithm. Only an 64-bit nonce is supported');
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}
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$this->nonce = $nonce;
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$this->changed = true;
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$this->setEngine();
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}
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/**
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* Sets the counter.
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*
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* @param int $counter
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*/
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public function setCounter($counter)
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{
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$this->counter = $counter;
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$this->setEngine();
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}
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/**
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* Creates a Poly1305 key using the method discussed in RFC8439
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*
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* See https://tools.ietf.org/html/rfc8439#section-2.6.1
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*/
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protected function createPoly1305Key()
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{
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if ($this->nonce === false) {
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throw new InsufficientSetupException('No nonce has been defined');
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}
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if ($this->key === false) {
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throw new InsufficientSetupException('No key has been defined');
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}
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$c = clone $this;
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$c->setCounter(0);
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$c->usePoly1305 = false;
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$block = $c->encrypt(str_repeat("\0", 256));
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$this->setPoly1305Key(substr($block, 0, 32));
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if ($this->counter == 0) {
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$this->counter++;
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}
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}
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/**
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* Setup the self::ENGINE_INTERNAL $engine
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*
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* (re)init, if necessary, the internal cipher $engine
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*
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* _setup() will be called each time if $changed === true
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* typically this happens when using one or more of following public methods:
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*
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* - setKey()
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*
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* - setNonce()
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*
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* - First run of encrypt() / decrypt() with no init-settings
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*
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* @see self::setKey()
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* @see self::setNonce()
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* @see self::disableContinuousBuffer()
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*/
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protected function setup()
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{
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if (!$this->changed) {
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return;
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}
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$this->enbuffer = $this->debuffer = ['ciphertext' => '', 'counter' => $this->counter];
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$this->changed = false;
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if ($this->nonce === false) {
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throw new InsufficientSetupException('No nonce has been defined');
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}
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if ($this->key === false) {
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throw new InsufficientSetupException('No key has been defined');
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}
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if ($this->usePoly1305 && !isset($this->poly1305Key)) {
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$this->usingGeneratedPoly1305Key = true;
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$this->createPoly1305Key();
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}
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$key = $this->key;
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if (strlen($key) == 16) {
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$constant = 'expand 16-byte k';
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$key.= $key;
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} else {
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$constant = 'expand 32-byte k';
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}
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$this->p1 = substr($constant, 0, 4) .
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substr($key, 0, 16) .
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substr($constant, 4, 4) .
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$this->nonce .
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"\0\0\0\0";
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$this->p2 = substr($constant, 8, 4) .
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substr($key, 16, 16) .
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substr($constant, 12, 4);
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}
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/**
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* Setup the key (expansion)
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*/
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protected function setupKey()
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{
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// Salsa20 does not utilize this method
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}
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/**
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* Encrypts a message.
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*
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* @see \phpseclib\Crypt\Common\SymmetricKey::decrypt()
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* @see self::crypt()
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* @param string $plaintext
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* @return string $ciphertext
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*/
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public function encrypt($plaintext)
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{
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$ciphertext = $this->crypt($plaintext, self::ENCRYPT);
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if (isset($this->poly1305Key)) {
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$this->newtag = $this->poly1305($ciphertext);
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}
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return $ciphertext;
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}
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/**
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* Decrypts a message.
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*
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* $this->decrypt($this->encrypt($plaintext)) == $this->encrypt($this->encrypt($plaintext)).
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* At least if the continuous buffer is disabled.
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*
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* @see \phpseclib\Crypt\Common\SymmetricKey::encrypt()
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* @see self::crypt()
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* @param string $ciphertext
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* @return string $plaintext
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*/
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public function decrypt($ciphertext)
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{
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if (isset($this->poly1305Key)) {
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if ($this->oldtag === false) {
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throw new InsufficientSetupException('Authentication Tag has not been set');
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}
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$newtag = $this->poly1305($ciphertext);
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if ($this->oldtag != substr($newtag, 0, strlen($this->oldtag))) {
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$this->oldtag = false;
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throw new BadDecryptionException('Derived authentication tag and supplied authentication tag do not match');
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}
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$this->oldtag = false;
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}
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return $this->crypt($ciphertext, self::DECRYPT);
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}
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/**
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* Encrypts a block
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*
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* @param string $in
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*/
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protected function encryptBlock($in)
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{
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// Salsa20 does not utilize this method
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}
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/**
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* Decrypts a block
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*
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* @param string $in
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*/
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protected function decryptBlock($in)
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{
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// Salsa20 does not utilize this method
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}
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/**
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* Encrypts or decrypts a message.
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*
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* @see self::encrypt()
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* @see self::decrypt()
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* @param string $text
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* @param int $mode
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* @return string $text
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*/
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private function crypt($text, $mode)
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{
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$this->setup();
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if (!$this->continuousBuffer) {
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if ($this->engine == self::ENGINE_OPENSSL) {
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$iv = pack('V', $this->counter) . $this->p2;
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return openssl_encrypt(
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$text,
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$this->cipher_name_openssl,
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$this->key,
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OPENSSL_RAW_DATA,
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$iv
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);
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}
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$i = $this->counter;
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$blocks = str_split($text, 64);
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foreach ($blocks as &$block) {
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$block^= static::salsa20($this->p1 . pack('V', $i++) . $this->p2);
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}
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return implode('', $blocks);
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}
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if ($mode == self::ENCRYPT) {
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$buffer = &$this->enbuffer;
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} else {
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$buffer = &$this->debuffer;
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}
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if (strlen($buffer['ciphertext'])) {
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$ciphertext = $text ^ Strings::shift($buffer['ciphertext'], strlen($text));
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$text = substr($text, strlen($ciphertext));
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if (!strlen($text)) {
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return $ciphertext;
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}
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}
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$overflow = strlen($text) % 64; // & 0x3F
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if ($overflow) {
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$text2 = Strings::pop($text, $overflow);
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if ($this->engine == self::ENGINE_OPENSSL) {
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$iv = pack('V', $buffer['counter']) . $this->p2;
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// at this point $text should be a multiple of 64
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$buffer['counter']+= (strlen($text) >> 6) + 1; // ie. divide by 64
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$encrypted = openssl_encrypt(
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$text . str_repeat("\0", 64),
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$this->cipher_name_openssl,
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$this->key,
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OPENSSL_RAW_DATA,
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$iv
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);
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$temp = Strings::pop($encrypted, 64);
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} else {
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$blocks = str_split($text, 64);
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if (strlen($text)) {
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foreach ($blocks as &$block) {
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$block^= static::salsa20($this->p1 . pack('V', $buffer['counter']++) . $this->p2);
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}
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}
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$encrypted = implode('', $blocks);
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$temp = static::salsa20($this->p1 . pack('V', $buffer['counter']++) . $this->p2);
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}
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$ciphertext.= $encrypted . ($text2 ^ $temp);
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$buffer['ciphertext'] = substr($temp, $overflow);
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} elseif (!strlen($buffer['ciphertext'])) {
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if ($this->engine == self::ENGINE_OPENSSL) {
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$iv = pack('V', $buffer['counter']) . $this->p2;
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$buffer['counter']+= (strlen($text) >> 6);
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$ciphertext.= openssl_encrypt(
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$text,
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$this->cipher_name_openssl,
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$this->key,
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OPENSSL_RAW_DATA,
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$iv
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);
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} else {
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$blocks = str_split($text, 64);
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foreach ($blocks as &$block) {
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$block^= static::salsa20($this->p1 . pack('V', $buffer['counter']++) . $this->p2);
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}
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$ciphertext.= implode('', $blocks);
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}
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}
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return $ciphertext;
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}
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/**
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* Left Rotate
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*
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* @param int $x
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* @param int $n
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* @return int
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*/
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protected static function leftRotate($x, $n)
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{
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$r1 = $x << $n;
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if (PHP_INT_SIZE == 8) {
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$r1&= 0xFFFFFFFF;
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$r2 = ($x & 0xFFFFFFFF) >> (32 - $n);
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} else {
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$r2 = $x >> (32 - $n);
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$r2&= (1 << $n) - 1;
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}
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return $r1 | $r2;
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}
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/**
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* The quarterround function
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*
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* @param int $a
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* @param int $b
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* @param int $c
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* @param int $d
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*/
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protected static function quarterRound(&$a, &$b, &$c, &$d)
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{
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$b^= self::leftRotate($a + $d, 7);
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$c^= self::leftRotate($b + $a, 9);
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$d^= self::leftRotate($c + $b, 13);
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$a^= self::leftRotate($d + $c, 18);
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}
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/**
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* The doubleround function
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*
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* @param int $x0...$x16
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*/
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protected static function doubleRound(&$x0, &$x1, &$x2, &$x3, &$x4, &$x5, &$x6, &$x7, &$x8, &$x9, &$x10, &$x11, &$x12, &$x13, &$x14, &$x15)
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{
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// columnRound
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static::quarterRound( $x0, $x4, $x8, $x12);
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static::quarterRound( $x5, $x9, $x13, $x1);
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static::quarterRound($x10, $x14, $x2, $x6);
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static::quarterRound($x15, $x3, $x7, $x11);
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// rowRound
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static::quarterRound( $x0, $x1, $x2, $x3);
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static::quarterRound( $x5, $x6, $x7, $x4);
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static::quarterRound($x10, $x11, $x8, $x9);
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static::quarterRound($x15, $x12, $x13, $x14);
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}
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/**
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* The Salsa20 hash function function
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*
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* @param string $x
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*/
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protected static function salsa20($x)
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{
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$z = $x = unpack('V*', $x);
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for ($i = 0; $i < 10; $i++) {
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static::doubleRound(...$z);
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}
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for ($i = 1; $i <= 16; $i++) {
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$x[$i]+= $z[$i];
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}
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return pack('V*', ...$x);
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}
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/**
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* Calculates Poly1305 MAC
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*
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* @see self::decrypt()
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* @see self::encrypt()
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* @access private
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* @param string $text
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* @return string
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*/
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protected function poly1305($ciphertext)
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{
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if (!$this->usingGeneratedPoly1305Key) {
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return parent::poly1305($this->aad . $ciphertext);
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} else {
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/*
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sodium_crypto_aead_chacha20poly1305_encrypt does not calculate the poly1305 tag
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the same way sodium_crypto_aead_chacha20poly1305_ietf_encrypt does. you can see
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how the latter encrypts it in Salsa20::encrypt(). here's how the former encrypts
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it:
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$this->newtag = $this->poly1305(
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$this->aad .
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pack('V', strlen($this->aad)) . "\0\0\0\0" .
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$ciphertext .
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pack('V', strlen($ciphertext)) . "\0\0\0\0"
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);
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phpseclib opts to use the IETF construction, even when the nonce is 64-bits
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instead of 96-bits
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*/
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return parent::poly1305(
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self::nullPad128($this->aad) .
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self::nullPad128($ciphertext) .
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pack('V', strlen($this->aad)) . "\0\0\0\0" .
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pack('V', strlen($ciphertext)) . "\0\0\0\0"
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);
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}
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}
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}
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