* setKey('abcdefghijklmnopqrstuvwx'); * * $size = 10 * 1024; * $plaintext = ''; * for ($i = 0; $i < $size; $i++) { * $plaintext.= 'a'; * } * * echo $des->decrypt($des->encrypt($plaintext)); * ?> * * * @author Jim Wigginton * @copyright 2007 Jim Wigginton * @license http://www.opensource.org/licenses/mit-license.html MIT License * @link http://phpseclib.sourceforge.net */ namespace phpseclib3\Crypt; /** * Pure-PHP implementation of Triple DES. * * @author Jim Wigginton */ class TripleDES extends DES { /** * Encrypt / decrypt using inner chaining * * Inner chaining is used by SSH-1 and is generally considered to be less secure then outer chaining (self::MODE_CBC3). */ const MODE_3CBC = -2; /** * Encrypt / decrypt using outer chaining * * Outer chaining is used by SSH-2 and when the mode is set to \phpseclib3\Crypt\Common\BlockCipher::MODE_CBC. */ const MODE_CBC3 = self::MODE_CBC; /** * Key Length (in bytes) * * @see \phpseclib3\Crypt\TripleDES::setKeyLength() * @var int */ protected $key_length = 24; /** * The mcrypt specific name of the cipher * * @see \phpseclib3\Crypt\DES::cipher_name_mcrypt * @see \phpseclib3\Crypt\Common\SymmetricKey::cipher_name_mcrypt * @var string */ protected $cipher_name_mcrypt = 'tripledes'; /** * Optimizing value while CFB-encrypting * * @see \phpseclib3\Crypt\Common\SymmetricKey::cfb_init_len * @var int */ protected $cfb_init_len = 750; /** * max possible size of $key * * @see self::setKey() * @see \phpseclib3\Crypt\DES::setKey() * @var string */ protected $key_length_max = 24; /** * Internal flag whether using self::MODE_3CBC or not * * @var bool */ private $mode_3cbc; /** * The \phpseclib3\Crypt\DES objects * * Used only if $mode_3cbc === true * * @var array */ private $des; /** * Default Constructor. * * Determines whether or not the mcrypt or OpenSSL extensions should be used. * * $mode could be: * * - ecb * * - cbc * * - ctr * * - cfb * * - ofb * * - 3cbc * * - cbc3 (same as cbc) * * @see \phpseclib3\Crypt\DES::__construct() * @see \phpseclib3\Crypt\Common\SymmetricKey::__construct() * @param string $mode */ public function __construct($mode) { switch (strtolower($mode)) { // In case of self::MODE_3CBC, we init as CRYPT_DES_MODE_CBC // and additional flag us internally as 3CBC case '3cbc': parent::__construct('cbc'); $this->mode_3cbc = true; // This three $des'es will do the 3CBC work (if $key > 64bits) $this->des = [ new DES('cbc'), new DES('cbc'), new DES('cbc'), ]; // we're going to be doing the padding, ourselves, so disable it in the \phpseclib3\Crypt\DES objects $this->des[0]->disablePadding(); $this->des[1]->disablePadding(); $this->des[2]->disablePadding(); break; case 'cbc3': $mode = 'cbc'; // fall-through // If not 3CBC, we init as usual default: parent::__construct($mode); if ($this->mode == self::MODE_STREAM) { throw new BadModeException('Block ciphers cannot be ran in stream mode'); } } } /** * Test for engine validity * * This is mainly just a wrapper to set things up for \phpseclib3\Crypt\Common\SymmetricKey::isValidEngine() * * @see \phpseclib3\Crypt\Common\SymmetricKey::__construct() * @param int $engine * @return bool */ protected function isValidEngineHelper($engine) { if ($engine == self::ENGINE_OPENSSL) { $this->cipher_name_openssl_ecb = 'des-ede3'; $mode = $this->openssl_translate_mode(); $this->cipher_name_openssl = $mode == 'ecb' ? 'des-ede3' : 'des-ede3-' . $mode; } return parent::isValidEngineHelper($engine); } /** * Sets the initialization vector. * * SetIV is not required when \phpseclib3\Crypt\Common\SymmetricKey::MODE_ECB is being used. * * @see \phpseclib3\Crypt\Common\SymmetricKey::setIV() * @param string $iv */ public function setIV($iv) { parent::setIV($iv); if ($this->mode_3cbc) { $this->des[0]->setIV($iv); $this->des[1]->setIV($iv); $this->des[2]->setIV($iv); } } /** * Sets the key length. * * Valid key lengths are 128 and 192 bits. * * If you want to use a 64-bit key use DES.php * * @see \phpseclib3\Crypt\Common\SymmetricKey:setKeyLength() * @throws \LengthException if the key length is invalid * @param int $length */ public function setKeyLength($length) { switch ($length) { case 128: case 192: break; default: throw new \LengthException('Key size of ' . $length . ' bits is not supported by this algorithm. Only keys of sizes 128 or 192 bits are supported'); } parent::setKeyLength($length); } /** * Sets the key. * * Triple DES can use 128-bit (eg. strlen($key) == 16) or 192-bit (eg. strlen($key) == 24) keys. * * DES also requires that every eighth bit be a parity bit, however, we'll ignore that. * * @see \phpseclib3\Crypt\DES::setKey() * @see \phpseclib3\Crypt\Common\SymmetricKey::setKey() * @throws \LengthException if the key length is invalid * @param string $key */ public function setKey($key) { if ($this->explicit_key_length !== false && strlen($key) != $this->explicit_key_length) { throw new \LengthException('Key length has already been set to ' . $this->explicit_key_length . ' bytes and this key is ' . strlen($key) . ' bytes'); } switch (strlen($key)) { case 16: $key .= substr($key, 0, 8); break; case 24: break; default: throw new \LengthException('Key of size ' . strlen($key) . ' not supported by this algorithm. Only keys of sizes 16 or 24 are supported'); } // copied from self::setKey() $this->key = $key; $this->key_length = strlen($key); $this->changed = $this->nonIVChanged = true; $this->setEngine(); if ($this->mode_3cbc) { $this->des[0]->setKey(substr($key, 0, 8)); $this->des[1]->setKey(substr($key, 8, 8)); $this->des[2]->setKey(substr($key, 16, 8)); } } /** * Encrypts a message. * * @see \phpseclib3\Crypt\Common\SymmetricKey::encrypt() * @param string $plaintext * @return string $cipertext */ public function encrypt($plaintext) { // parent::en/decrypt() is able to do all the work for all modes and keylengths, // except for: self::MODE_3CBC (inner chaining CBC) with a key > 64bits // if the key is smaller then 8, do what we'd normally do if ($this->mode_3cbc && strlen($this->key) > 8) { return $this->des[2]->encrypt( $this->des[1]->decrypt( $this->des[0]->encrypt( $this->pad($plaintext) ) ) ); } return parent::encrypt($plaintext); } /** * Decrypts a message. * * @see \phpseclib3\Crypt\Common\SymmetricKey::decrypt() * @param string $ciphertext * @return string $plaintext */ public function decrypt($ciphertext) { if ($this->mode_3cbc && strlen($this->key) > 8) { return $this->unpad( $this->des[0]->decrypt( $this->des[1]->encrypt( $this->des[2]->decrypt( str_pad($ciphertext, (strlen($ciphertext) + 7) & 0xFFFFFFF8, "\0") ) ) ) ); } return parent::decrypt($ciphertext); } /** * 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($plaintext, 8, 8))); * * * With the continuous buffer disabled, these would yield the same output. With it enabled, they yield different * outputs. The reason is due to the fact that the initialization vector's change after every encryption / * decryption round when the continuous buffer is enabled. When it's disabled, they remain constant. * * Put another way, when the continuous buffer is enabled, the state of the \phpseclib3\Crypt\DES() object changes after each * encryption / decryption round, whereas otherwise, it'd remain constant. For this reason, it's recommended that * continuous buffers not be used. They do offer better security and are, in fact, sometimes required (SSH uses them), * however, they are also less intuitive and more likely to cause you problems. * * @see \phpseclib3\Crypt\Common\SymmetricKey::enableContinuousBuffer() * @see self::disableContinuousBuffer() */ public function enableContinuousBuffer() { parent::enableContinuousBuffer(); if ($this->mode_3cbc) { $this->des[0]->enableContinuousBuffer(); $this->des[1]->enableContinuousBuffer(); $this->des[2]->enableContinuousBuffer(); } } /** * Treat consecutive packets as if they are a discontinuous buffer. * * The default behavior. * * @see \phpseclib3\Crypt\Common\SymmetricKey::disableContinuousBuffer() * @see self::enableContinuousBuffer() */ public function disableContinuousBuffer() { parent::disableContinuousBuffer(); if ($this->mode_3cbc) { $this->des[0]->disableContinuousBuffer(); $this->des[1]->disableContinuousBuffer(); $this->des[2]->disableContinuousBuffer(); } } /** * Creates the key schedule * * @see \phpseclib3\Crypt\DES::setupKey() * @see \phpseclib3\Crypt\Common\SymmetricKey::setupKey() */ protected function setupKey() { switch (true) { // if $key <= 64bits we configure our internal pure-php cipher engine // to act as regular [1]DES, not as 3DES. mcrypt.so::tripledes does the same. case strlen($this->key) <= 8: $this->des_rounds = 1; break; // otherwise, if $key > 64bits, we configure our engine to work as 3DES. default: $this->des_rounds = 3; // (only) if 3CBC is used we have, of course, to setup the $des[0-2] keys also separately. if ($this->mode_3cbc) { $this->des[0]->setupKey(); $this->des[1]->setupKey(); $this->des[2]->setupKey(); // because $des[0-2] will, now, do all the work we can return here // not need unnecessary stress parent::setupKey() with our, now unused, $key. return; } } // setup our key parent::setupKey(); } /** * Sets the internal crypt engine * * @see \phpseclib3\Crypt\Common\SymmetricKey::__construct() * @see \phpseclib3\Crypt\Common\SymmetricKey::setPreferredEngine() * @param int $engine */ public function setPreferredEngine($engine) { if ($this->mode_3cbc) { $this->des[0]->setPreferredEngine($engine); $this->des[1]->setPreferredEngine($engine); $this->des[2]->setPreferredEngine($engine); } parent::setPreferredEngine($engine); } }