PHP_CRYPT\Cipher_Skipjack

Complexity

Total Complexity

39

Size/Duplication

Total Lines	353
Duplicated Lines	51.27 %

Coupling/Cohesion

Components	1
Dependencies	1

Importance

Changes

0

10 Methods

Rating	Name	Duplication	Size	Complexity
A	__construct()	0	14	1
A	__destruct()	0	4	1
D	encrypt()	24	28	10
D	decrypt()	24	28	10
C	gPermutation()	26	39	8
A	ruleA()	48	48	2
A	ruleB()	49	49	2
A	expandKey()	8	17	3
A	initTables()	0	21	1
A	type()	0	4	1

<?php
/*
 * Author: Ryan Gilfether
 * URL: http://www.gilfether.com/phpCrypt
 * Date: April 23, 2013
 * Copyright (C) 2013 Ryan Gilfether
 *
 * This file is part of phpCrypt
 *
 * phpCrypt is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, see <http://www.gnu.org/licenses/>.
 */

namespace PHP_CRYPT;
require_once(dirname(__FILE__)."/../Cipher.php");
require_once(dirname(__FILE__)."/../phpCrypt.php");


/**
 * Implements Skipjack Encryption
 * Resources used to implement this algorithm:
 * csrc.nist.gov/groups/ST/toolkit/documents/skipjack/skipjack.pdf
 * http://calccrypto.wikidot.com/algorithms:skipjack
 * http://www.quadibloc.com/crypto/co040303.htm
 *
 * @author Ryan Gilfether
 * @link http://www.gilfether.com/phpcrypt
 * @copyright 2013 Ryan Gilfether
 */
class Cipher_Skipjack extends Cipher
{
    /** @type integer BYTES_BLOCK The size of the block, in bytes */
    const BYTES_BLOCK = 8; // 64 bits

    /** @type integer BYTES_KEY The size of the key, in bytes */
    const BYTES_KEY = 10; // 80 bits

    /** @type string $expanded_key The expanded key */
    private $expanded_key = "";

    /** @type array $_f The Skipjack F-Table, this is a constant */
    private static $_f = array();


    /**
     * Constructor
     *
     * @param string $key The key used for Encryption/Decryption
     * @return void

Adding a @return annotation to constructors is generally not recommended as a constructor does not have a meaningful return value.

     */
    public function __construct($key)
    {
        // set the Skipjack key
        parent::__construct(PHP_Crypt::CIPHER_SKIPJACK, $key, self::BYTES_KEY);

        // initialize variables
        $this->initTables();

        // set the block size used
        $this->blockSize(self::BYTES_BLOCK);

        // expand the key from 10 bytes to 128 bytes
        $this->expandKey();
    }


    /**
     * Destructor
     *
     * @return void
     */
    public function __destruct()
    {
        parent::__destruct();
    }


    /**
     * Encrypt plain text data using Skipjack
     *
     * @return boolean Returns true
     */
    public function encrypt(&$text)

This method seems to be duplicated in your project.

    {
        $this->operation(parent::ENCRYPT);

        for ($i = 1; $i <= 32; ++$i)
        {
            $pos = (4 * $i) - 4;
            $subkey = substr($this->expanded_key, $pos, 4);

            if ($i >= 1 && $i <= 8) {
                            $this->ruleA($text, $subkey, $i);
            }

            if ($i >= 9 && $i <= 16) {
                            $this->ruleB($text, $subkey, $i);
            }

            if ($i >= 17 && $i <= 24) {
                            $this->ruleA($text, $subkey, $i);
            }

            if ($i >= 25 && $i <= 32) {
                            $this->ruleB($text, $subkey, $i);
            }
        }

        return true;
    }


    /**
     * Decrypt a Skipjack encrypted string
     *
     * @return boolean Returns true
     */
    public function decrypt(&$text)

This method seems to be duplicated in your project.

    {
        $this->operation(parent::DECRYPT);

        for ($i = 32; $i >= 1; --$i)
        {
            $pos = ($i - 1) * 4;
            $subkey = substr($this->expanded_key, $pos, 4);

            if ($i <= 32 && $i >= 25) {
                            $this->ruleB($text, $subkey, $i);
            }

            if ($i <= 24 && $i >= 17) {
                            $this->ruleA($text, $subkey, $i);
            }

            if ($i <= 16 && $i >= 9) {
                            $this->ruleB($text, $subkey, $i);
            }

            if ($i <= 8 && $i >= 1) {
                            $this->ruleA($text, $subkey, $i);
            }
        }

        return true;
    }


    /**
     * For the G Permutations, the input data is 2 Bytes The first byte is
     * the left side and the second is the right side.The round key is 4 bytes
     * long (Indices 8*i-8 to 8*i), which is split as 4 pieces: K0, K1, K2, K3
     *
     * @param string $bytes A 2 byte string
     * @param string $key 4 bytes of $this->expanded_key
     * @return string A 2 byte string, the G Permutation of $bytes
     */
    private function gPermutation($bytes, $key)
    {
        $left = ord($bytes[0]);
        $right = ord($bytes[1]);

        if ($this->operation() == parent::ENCRYPT)
        {
            for ($i = 0; $i < 4; ++$i)
            {
                if ($i == 0 || $i == 2)
                {
                    $pos = $right ^ $this->str2Dec($key[$i]);
                    $left = $left ^ self::$_f[$pos];
                } else
                {
                    $pos = $left ^ $this->str2Dec($key[$i]);
                    $right = $right ^ self::$_f[$pos];
                }
            }
        } else // parent::DECRYPT
        {
            // we do the same as in encryption, but apply the key backwards,
            // from key[3] to key[0]

43% of this comment could be valid code. Did you maybe forget this after debugging?

            for ($i = 3; $i >= 0; --$i)
            {
                if ($i == 0 || $i == 2)
                {
                    $pos = $right ^ $this->str2Dec($key[$i]);
                    $left = $left ^ self::$_f[$pos];
                } else
                {
                    $pos = $left ^ $this->str2Dec($key[$i]);
                    $right = $right ^ self::$_f[$pos];
                }
            }
        }

        return $this->dec2Str($left).$this->dec2Str($right);
    }


    /**
     * Perform SkipJacks RuleA function. Split the data into 4 parts,
     * 2 bytes each: W0, W1, W2, W3.
     *
     * @param string $bytes An 8 byte string
     * @param string $key 4 bytes of $this->expanded_key
     * @param integer $i The round number
     * @return void
     */
    private function ruleA(&$bytes, $key, $i)

This method seems to be duplicated in your project.

    {
        $w = str_split($bytes, 2);

        if ($this->operation() == parent::ENCRYPT)
        {
            /*
			 * Set the W3 as the old W2
			 * Set the W2 as the old W1
			 * Set the W1 as the G(W0)
			 * Set the W0 as the W1 xor W4 xor i
			 */

            $w[4] = $w[3];
            $w[3] = $w[2];
            $w[2] = $w[1];
            $w[1] = $this->gPermutation($w[0], $key);

            $hex1 = $this->str2Hex($w[1]);
            $hex4 = $this->str2Hex($w[4]);
            $hexi = $this->dec2Hex($i);
            $w[0] = $this->xorHex($hex1, $hex4, $hexi);
            $w[0] = $this->hex2Str($w[0]);
        } else // parent::DECRYPT
        {
            /*
			 * Set W4 as W0 xor W1 xor i
			 * Set W0 as Inverse G(W1)
			 * Set W1 as the old W2
			 * Set W2 as the old W3
			 * Set W3 as W4
			 */

            $hex0 = $this->str2Hex($w[0]);
            $hex1 = $this->str2Hex($w[1]);
            $hexi = $this->dec2Hex($i);
            $w[4] = $this->xorHex($hex0, $hex1, $hexi);
            $w[4] = $this->hex2Str($w[4]);

            $w[0] = $this->gPermutation($w[1], $key);
            $w[1] = $w[2];
            $w[2] = $w[3];
            $w[3] = $w[4];
        }

        // glue all the pieces back together
        $bytes = $w[0].$w[1].$w[2].$w[3];
    }


    /**
     * Perform SkipJacks RuleB function. Split the data into 4 parts,
     * 2 bytes each: W0, W1, W2, W3.
     *
     * @param string $bytes An 8 bytes string
     * @param string $key 4 bytes of $this->expanded_key
     * @param integer $i The round number
     * @return void
     */
    private function ruleB(&$bytes, $key, $i)

This method seems to be duplicated in your project.

    {
        $w = str_split($bytes, 2);

        if ($this->operation() == parent::ENCRYPT)
        {
            /*
			 * Set the new W3 as the old W2
			 * Set the new W2 as the old W0 xor old W1 xor i
			 * Set the new W1 as G(old W0)
			 * Set the new W0 as the old W3
			 */

            $w[4] = $w[3];
            $w[3] = $w[2];

            $hex0 = $this->str2Hex($w[0]);
            $hex1 = $this->str2Hex($w[1]);
            $hexi = $this->dec2Hex($i);
            $w[2] = $this->xorHex($hex0, $hex1, $hexi);
            $w[2] = $this->hex2Str($w[2]);

            $w[1] = $this->gPermutation($w[0], $key);
            $w[0] = $w[4];
        } else // parent::DECRYPT
        {
            /*
			 * Set W4 as the old W0
			 * Set new W0 as Inverse G(old W1)
			 * Set new W1 as Inverse G(old W1) xor old W2 xor i
			 * Set new W2 as the old W3
			 * Set new W0 as the old W4
			 */

            $w[4] = $w[0];
            $w[0] = $this->gPermutation($w[1], $key);

            $hex0 = $this->str2Hex($w[0]);
            $hex2 = $this->str2Hex($w[2]);
            $hexi = $this->dec2Hex($i);
            $w[1] = $this->xorHex($hex0, $hex2, $hexi);
            $w[1] = $this->hex2Str($w[1]);

            $w[2] = $w[3];
            $w[3] = $w[4];
        }

        $bytes = $w[0].$w[1].$w[2].$w[3];
    }


    /**
     * Expands the key from 10 bytes, to 128 bytes
     * This is done by copying the key 1 byte at a time and
     * appending it to $this->expanded_key, when we reach the
     * end of the key, we start over at position 0 and continue
     * until we reach 128 bytes
     *
     * @return void
     */
    private function expandKey()
    {
        $this->expanded_key = "";
        $key_bytes = $this->keySize();
        $key = $this->key();
        $pos = 0;

        for ($i = 0; $i < 128; ++$i)
        {
            if ($pos == $key_bytes) {
                            $pos = 0;
            }

            $this->expanded_key .= $key[$pos];
            ++$pos;
        }
    }


    /**
     * Initialize all the tables, this function is called inside the constructor
     *
     * @return void
     */
    private function initTables()
    {
        self::$_f = array(
            0xa3, 0xd7, 0x09, 0x83, 0xf8, 0x48, 0xf6, 0xf4, 0xb3, 0x21, 0x15, 0x78, 0x99, 0xb1, 0xaf, 0xf9,
            0xe7, 0x2d, 0x4d, 0x8a, 0xce, 0x4c, 0xca, 0x2e, 0x52, 0x95, 0xd9, 0x1e, 0x4e, 0x38, 0x44, 0x28,
            0x0a, 0xdf, 0x02, 0xa0, 0x17, 0xf1, 0x60, 0x68, 0x12, 0xb7, 0x7a, 0xc3, 0xe9, 0xfa, 0x3d, 0x53,
            0x96, 0x84, 0x6b, 0xba, 0xf2, 0x63, 0x9a, 0x19, 0x7c, 0xae, 0xe5, 0xf5, 0xf7, 0x16, 0x6a, 0xa2,
            0x39, 0xb6, 0x7b, 0x0f, 0xc1, 0x93, 0x81, 0x1b, 0xee, 0xb4, 0x1a, 0xea, 0xd0, 0x91, 0x2f, 0xb8,
            0x55, 0xb9, 0xda, 0x85, 0x3f, 0x41, 0xbf, 0xe0, 0x5a, 0x58, 0x80, 0x5f, 0x66, 0x0b, 0xd8, 0x90,
            0x35, 0xd5, 0xc0, 0xa7, 0x33, 0x06, 0x65, 0x69, 0x45, 0x00, 0x94, 0x56, 0x6d, 0x98, 0x9b, 0x76,
            0x97, 0xfc, 0xb2, 0xc2, 0xb0, 0xfe, 0xdb, 0x20, 0xe1, 0xeb, 0xd6, 0xe4, 0xdd, 0x47, 0x4a, 0x1d,
            0x42, 0xed, 0x9e, 0x6e, 0x49, 0x3c, 0xcd, 0x43, 0x27, 0xd2, 0x07, 0xd4, 0xde, 0xc7, 0x67, 0x18,
            0x89, 0xcb, 0x30, 0x1f, 0x8d, 0xc6, 0x8f, 0xaa, 0xc8, 0x74, 0xdc, 0xc9, 0x5d, 0x5c, 0x31, 0xa4,
            0x70, 0x88, 0x61, 0x2c, 0x9f, 0x0d, 0x2b, 0x87, 0x50, 0x82, 0x54, 0x64, 0x26, 0x7d, 0x03, 0x40,
            0x34, 0x4b, 0x1c, 0x73, 0xd1, 0xc4, 0xfd, 0x3b, 0xcc, 0xfb, 0x7f, 0xab, 0xe6, 0x3e, 0x5b, 0xa5,
            0xad, 0x04, 0x23, 0x9c, 0x14, 0x51, 0x22, 0xf0, 0x29, 0x79, 0x71, 0x7e, 0xff, 0x8c, 0x0e, 0xe2,
            0x0c, 0xef, 0xbc, 0x72, 0x75, 0x6f, 0x37, 0xa1, 0xec, 0xd3, 0x8e, 0x62, 0x8b, 0x86, 0x10, 0xe8,
            0x08, 0x77, 0x11, 0xbe, 0x92, 0x4f, 0x24, 0xc5, 0x32, 0x36, 0x9d, 0xcf, 0xf3, 0xa6, 0xbb, 0xac,
            0x5e, 0x6c, 0xa9, 0x13, 0x57, 0x25, 0xb5, 0xe3, 0xbd, 0xa8, 0x3a, 0x01, 0x05, 0x59, 0x2a, 0x46
        );
    }


    /**
     * Indicates that this is a block cipher
     *
     * @return integer Returns Cipher::BLOCK
     */
    public function type()
    {
        return parent::BLOCK;
    }
}
?>

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