tgseclib/tests/Unit/Crypt/RC2Test.php

<?php
/**
 * @author    Andreas Fischer <bantu@phpbb.com>
 * @copyright MMXIII Andreas Fischer
 * @license   http://www.opensource.org/licenses/mit-license.html  MIT License
 */

use phpseclib\Crypt\Base;
use phpseclib\Crypt\RC2;

class Unit_Crypt_RC2Test extends PhpseclibTestCase
{
    var $engines = array(
        Base::ENGINE_INTERNAL => 'internal',
        Base::ENGINE_MCRYPT => 'mcrypt',
        Base::ENGINE_OPENSSL => 'OpenSSL',
    );

    public function engineVectors()
    {
        // tests from https://tools.ietf.org/html/rfc2268#page-8
        $tests = array(
            // key, effective key length, plaintext, ciphertext
            array('0000000000000000', 63, '0000000000000000', 'ebb773f993278eff'),
            array('ffffffffffffffff', 64, 'ffffffffffffffff', '278b27e42e2f0d49'),
            array('3000000000000000', 64, '1000000000000001', '30649edf9be7d2c2'),
            array('88', 64, '0000000000000000', '61a8a244adacccf0'),
            array('88bca90e90875a', 64, '0000000000000000', '6ccf4308974c267f'),
            array('88bca90e90875a7f0f79c384627bafb2', 64, '0000000000000000', '1a807d272bbe5db1'),
            array('88bca90e90875a7f0f79c384627bafb2', 128, '0000000000000000', '2269552ab0f85ca6'),
            array('88bca90e90875a7f0f79c384627bafb216f80a6f85920584c42fceb0be255daf1e', 129, '0000000000000000', '5b78d3a43dfff1f1')
        );
        $result = array();
        // @codingStandardsIgnoreStart
        foreach ($this->engines as $engine => $engineName) 
        foreach ($tests as $test)
            $result[] = array($engine, $engineName, $test[0], $test[1], $test[2], $test[3]);
        // @codingStandardsIgnoreEnd
        return $result;
    }

    // this test is just confirming RC2's key expansion
    public function testEncryptPadding()
    {
        $rc2 = new RC2(Base::MODE_ECB);

        // unlike Crypt_AES / Crypt_Rijndael, when you tell Crypt_RC2 that the key length is 128-bits the key isn't null padded to that length.
        // instead, RC2 key expansion is used to extend it out to that length. this isn't done for AES / Rijndael since that doesn't define any
        // sort of key expansion algorithm.

        // admittedly, phpseclib is inconsistent in this regard. RC4 and Blowfish support arbitrary key lengths between a certain range, as well,
        // and they don't have any way to set the key length. but then again, neither do those algorithms have their own key expansion algorithm,
        // whereas RC2 does. and technically, AES / Rijndael (and even Twofish) don't support arbitrary key lengths - they support variable key
        // lengths. so in some ways, i suppose this inconsistency somewhat makes sense, although the fact that Crypt_Twofish doesn't have a
        // setKeyLength() function whereas Crypt_AES / Crypt_Rijndael do not is, itself, an inconsistency.

        // but that said, Crypt_RC2 is inconsistent in other ways: if you pass a 128-bit (16-byte) key to it via setKey() the key is not treated
        // as a 128-bit key but rather as a 1024-bit key and is expanded accordingly, not via null padding, but via RC2's key expansion algorithm.

        // this behavior is in contrast to mcrypt, which extends keys via null padding to 1024 bits. it is also in contrast to OpenSSL, which
        // extends keys, via null padding, to 128 bits. mcrypt's approach seems preferable as one can simulate 128 bit keys by using RC2's
        // key expansion algorithm to extend the key to 1024 bits and then changing the first byte of the new key with an inverse pitable mapping.
        // in contrast, to my knowledge, there is no technique for expanding a key less than 128 bits to 128 bits, via RC2 key expansion. the only
        // scenario in that regard is null padding.

        // simple truncation is insufficient, since, quoting RFC2268, "the purpose of the key-expansion algorithm [in RC2] is to modify the key buffer
        // so that each bit of the expanded key depends in a complicated way on every bit of the supplied input key".

        // now, to OpenSSL's credit, null padding is internally consistent with OpenSSL. OpenSSL only supports fixed length keys. For rc2, rc4 and
        // bf (blowfish), all keys are 128 bits (or are null padded / truncated accordingly). to use 40-bit or 64-bit keys with RC4 with OpenSSL you
        // don't use the rc4 algorithm - you use the rc4-40 or rc4-64 algorithm. and similarily, it's not aes-cbc that you use - it's either aes-128-cbc
        // or aes-192-cbc or aes-256-cbc. this is in contrast to mcrypt, which (with the exception of RC2) actually supports variable and arbitrary
        // length keys.

        // superficially, it seens like Rijndael would be another exception to mcrypt's key length handling, but it in fact is not. the reason being that,
        // with mcrypt, when you specify MCRYPT_RIJNDAEL_128 or MCRYPT_RIJNDAEL_192 or MCRYPT_RIJNDAEL_256 the numbers at the end aren't referring to the
        // key length, but rather, the block length. ie. Rijndael, unlike most block ciphers, doesn't just have a variable (but not arbitrary) key length -
        // it also has a variable block length. AES's block length, however, is not variable, so technically, only MCRYPT_RIJNDAEL_128 is AES.

        $rc2->setKey(str_repeat('d', 16), 128);

        $rc2->setPreferredEngine(Base::ENGINE_INTERNAL);
        $internal = $rc2->encrypt('d');

        $result = pack('H*', 'e3b36057f4821346');
        $this->assertEquals($result, $internal, 'Failed asserting that the internal engine produced the correct result');

        $rc2->setPreferredEngine(Base::ENGINE_MCRYPT);
        if ($rc2->getEngine() == Base::ENGINE_MCRYPT) {
            $mcrypt = $rc2->encrypt('d');
            $this->assertEquals($result, $mcrypt, 'Failed asserting that the mcrypt engine produced the correct result');
        } else {
            self::markTestSkipped('Unable to initialize mcrypt engine');
        }

        $rc2->setPreferredEngine(Base::ENGINE_OPENSSL);
        if ($rc2->getEngine() == Base::ENGINE_OPENSSL) {
            $openssl = $rc2->encrypt('d');
            $this->assertEquals($result, $openssl,  'Failed asserting that the OpenSSL engine produced the correct result');
        } else {
            self::markTestSkipped('Unable to initialize OpenSSL engine');
        }
    }

    /**
    * @dataProvider engineVectors
    */
    public function testVectors($engine, $engineName, $key, $keyLen, $plaintext, $ciphertext)
    {
        $rc2 = new RC2();
        $rc2->disablePadding();
        $rc2->setKeyLength($keyLen);
        $rc2->setKey(pack('H*', $key)); // could also do $rc2->setKey(pack('H*', $key), $keyLen)
        if (!$rc2->isValidEngine($engine)) {
            self::markTestSkipped('Unable to initialize ' . $engineName . ' engine');
        }
        $rc2->setPreferredEngine($engine);

        $result = bin2hex($rc2->encrypt(pack('H*', $plaintext)));
        $this->assertEquals($result, $ciphertext, "Failed asserting that $plaintext yielded expected output in $engineName engine");
    }
}