AesCtr::decrypt() - Code Metrics - Inspection of "Update AesCtrTest.php" - mmeyer2k/dcrypt - Measure and Improve Code Quality continuously with Scrutinizer

Completed

Push — master ( ca77ed...3bcd04 )

by Michael

created 2016-02-19 23:44 UTC

AesCtr::decrypt() B

↳ Parent: AesCtr

Complexity

Conditions	2
Paths	2

Size

Total Lines	30
Code Lines	11

Duplication

Lines	0
Ratio	0 %

Importance

Changes	2
Bugs	0	Features	1

Metric	Value
c	2
b	0
f	1
dl	0
loc	30
rs	8.8571
cc	2
eloc	11
nc	2
nop	3

<?php

/**
 * AesCtr.php
 * 
 * PHP version 5
 * 
 * @category Dcrypt
 * @package  Dcrypt
 * @author   Michael Meyer (mmeyer2k) <[email protected]>
 * @license  http://opensource.org/licenses/MIT The MIT License (MIT)
 * @link     https://github.com/mmeyer2k/dcrypt
 */

namespace Dcrypt;

/**
 * Symmetric AES-256-CTR encryption functions powered by OpenSSL.
 * 
 * @category Dcrypt
 * @package  Dcrypt
 * @author   Michael Meyer (mmeyer2k) <[email protected]>
 * @license  http://opensource.org/licenses/MIT The MIT License (MIT)
 * @link     https://github.com/mmeyer2k/dcrypt
 * @link     https://apigen.ci/github/mmeyer2k/dcrypt/namespace-Dcrypt.html
 */
class AesCtr extends Cryptobase
{

    /**
     * AES-256 cipher identifier that will be passed to openssl
     * 
     * @var string
     */
    const CIPHER = 'aes-256-ctr';

    /**
     * Size of initialization vector in bytes
     * 
     * @var int
     */
    const IVSIZE = 16;

    /**
     * Size of checksum in bytes
     * 
     * @var int
     */
    const CKSIZE = 32;

    /**
     * Decrypt cyphertext
     * 
     * @param string $cyphertext Cyphertext to decrypt
     * @param string $password   Password that should be used to decrypt input data
     * @param int    $cost       Number of HMAC iterations to perform on key
     * 
     * @return string|boolean Returns false on checksum validation failure
     */
    public static function decrypt($cyphertext, $password, $cost = 0)
    {
        // Find the IV at the beginning of the cypher text
        $iv = Str::substr($cyphertext, 0, self::IVSIZE);

        // Gather the key IV
        $keyiv = Str::substr($cyphertext, self::IVSIZE, self::IVSIZE);

        // Gather the checksum portion of the cypher text
        $chksum = Str::substr($cyphertext, self::IVSIZE * 2, self::CKSIZE);

        // Gather message portion of cyphertext after iv and checksum
        $message = Str::substr($cyphertext, self::IVSIZE * 2 + self::CKSIZE);

        // Derive key from password
        $key = self::key($password, $iv . $keyiv, $cost);

        // Calculate verification checksum
        $verify = self::checksum($message, $iv, $key);

        // Verify HMAC before decrypting
        if (!Str::equal($verify, $chksum)) {
            return static::invalidChecksum();
class YourClass
{
    private static function getTemperature() {
        return "3422 °C";
}

public static function getSomeVariable()
{
    return static::getTemperature();
}
        }

        // Decrypt message with padding
        $padded = \openssl_decrypt($message, self::CIPHER, $key, 1, $iv);

        return Pkcs7::unpad($padded);
    }

    /**
     * Encrypt plaintext
     * 
     * @param string $plaintext Plaintext string to encrypt.
     * @param string $password  Password used to encrypt data.
     * @param int    $cost      Number of HMAC iterations to perform on key
     * 
     * @return string 
     */
    public static function encrypt($plaintext, $password, $cost = 0)
    {
        // Generate IV of appropriate size.
        $iv = Random::get(self::IVSIZE);

        // Generage a second IV used only for the key. This helps to mitigate
        // the problem of encrypting twice with the same IV and key.
        $keyiv = Random::get(self::IVSIZE);

        // Derive key from password
        $key = self::key($password, $iv . $keyiv, $cost);

        $padded = Pkcs7::pad($plaintext, 16);

        // Encrypt the plaintext
        $message = \openssl_encrypt($padded, self::CIPHER, $key, 1, $iv);

        // Create the cypher text prefix (iv + checksum)
        $prefix = $iv . $keyiv . self::checksum($message, $iv, $key);

        // Return prefix + cyphertext
        return $prefix . $message;
    }

    /**
     * By default, \Dcrypt\Aes will will return false when the checksum is invalid.
     * Use AesExp to force an exception to be thrown instead.
     * 
     * @return false
     */
    private static function invalidChecksum()
    {
        return false;
    }

}


1			<?php
2
3			/**
4			* AesCtr.php
5			*
6			* PHP version 5
7			*
8			* @category Dcrypt
9			* @package Dcrypt
10			* @author Michael Meyer (mmeyer2k) <[email protected]>
11			* @license http://opensource.org/licenses/MIT The MIT License (MIT)
12			* @link https://github.com/mmeyer2k/dcrypt
13			*/
14
15			namespace Dcrypt;
16
17			/**
18			* Symmetric AES-256-CTR encryption functions powered by OpenSSL.
19			*
20			* @category Dcrypt
21			* @package Dcrypt
22			* @author Michael Meyer (mmeyer2k) <[email protected]>
23			* @license http://opensource.org/licenses/MIT The MIT License (MIT)
24			* @link https://github.com/mmeyer2k/dcrypt
25			* @link https://apigen.ci/github/mmeyer2k/dcrypt/namespace-Dcrypt.html
26			*/
27			class AesCtr extends Cryptobase
28			{
29
30			/**
31			* AES-256 cipher identifier that will be passed to openssl
32			*
33			* @var string
34			*/
35			const CIPHER = 'aes-256-ctr';
36
37			/**
38			* Size of initialization vector in bytes
39			*
40			* @var int
41			*/
42			const IVSIZE = 16;
43
44			/**
45			* Size of checksum in bytes
46			*
47			* @var int
48			*/
49			const CKSIZE = 32;
50
51			/**
52			* Decrypt cyphertext
53			*
54			* @param string $cyphertext Cyphertext to decrypt
55			* @param string $password Password that should be used to decrypt input data
56			* @param int $cost Number of HMAC iterations to perform on key
57			*
58			* @return string\|boolean Returns false on checksum validation failure
59			*/
60			public static function decrypt($cyphertext, $password, $cost = 0)
61			{
62			// Find the IV at the beginning of the cypher text
63			$iv = Str::substr($cyphertext, 0, self::IVSIZE);
64
65			// Gather the key IV
66			$keyiv = Str::substr($cyphertext, self::IVSIZE, self::IVSIZE);
67
68			// Gather the checksum portion of the cypher text
69			$chksum = Str::substr($cyphertext, self::IVSIZE * 2, self::CKSIZE);
70
71			// Gather message portion of cyphertext after iv and checksum
72			$message = Str::substr($cyphertext, self::IVSIZE * 2 + self::CKSIZE);
73
74			// Derive key from password
75			$key = self::key($password, $iv . $keyiv, $cost);
76
77			// Calculate verification checksum
78			$verify = self::checksum($message, $iv, $key);
79
80			// Verify HMAC before decrypting
81			if (!Str::equal($verify, $chksum)) {
82			return static::invalidChecksum();
			0 ignored issues – show Bug introduced 2016-02-19 19:55 UTC by Report Bug Copy Issue Report Since `invalidChecksum()` is declared private, calling it with `static` will lead to errors in possible sub-classes. You can either use `self`, or increase the visibility of `invalidChecksum()` to at least protected. Let’s assume you have a class which uses late-static binding: class YourClass { private static function getTemperature() { return "3422 °C"; } public static function getSomeVariable() { return static::getTemperature(); } } The code above will run fine in your PHP runtime. However, if you now create a sub-class and call the `getSomeVariable()` on that sub-class, you will receive a runtime error: class YourSubClass extends YourClass { private static function getTemperature() { return "-182 °C"; } } print YourSubClass::getSomeVariable(); // Will cause an access error. In the case above, it makes sense to update `SomeClass` to use `self` instead: class YourClass { private static function getTemperature() { return "3422 °C"; } public static function getSomeVariable() { return self::getTemperature(); } } Loading history...
83			}
84
85			// Decrypt message with padding
86			$padded = \openssl_decrypt($message, self::CIPHER, $key, 1, $iv);
87
88			return Pkcs7::unpad($padded);
89			}
90
91			/**
92			* Encrypt plaintext
93			*
94			* @param string $plaintext Plaintext string to encrypt.
95			* @param string $password Password used to encrypt data.
96			* @param int $cost Number of HMAC iterations to perform on key
97			*
98			* @return string
99			*/
100			public static function encrypt($plaintext, $password, $cost = 0)
101			{
102			// Generate IV of appropriate size.
103			$iv = Random::get(self::IVSIZE);
104
105			// Generage a second IV used only for the key. This helps to mitigate
106			// the problem of encrypting twice with the same IV and key.
107			$keyiv = Random::get(self::IVSIZE);
108
109			// Derive key from password
110			$key = self::key($password, $iv . $keyiv, $cost);
111
112			$padded = Pkcs7::pad($plaintext, 16);
113
114			// Encrypt the plaintext
115			$message = \openssl_encrypt($padded, self::CIPHER, $key, 1, $iv);
116
117			// Create the cypher text prefix (iv + checksum)
118			$prefix = $iv . $keyiv . self::checksum($message, $iv, $key);
119
120			// Return prefix + cyphertext
121			return $prefix . $message;
122			}
123
124			/**
125			* By default, \Dcrypt\Aes will will return false when the checksum is invalid.
126			* Use AesExp to force an exception to be thrown instead.
127			*
128			* @return false
129			*/
130			private static function invalidChecksum()
131			{
132			return false;
133			}
134
135			}
136

mmeyer2k / dcrypt

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AesCtr::decrypt() B

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