Crypto::calculateHMAC() - Code Metrics - Inspection of "Merge pull request #25714 from nextcloud/fix/23197..." - nextcloud/server - Measure and Improve Code Quality continuously with Scrutinizer

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Push — master ( 634b6b...393309 )

by Morris

created 2021-04-22 11:23 UTC

Crypto::calculateHMAC() A

↳ Parent: Crypto

Complexity

Conditions	2
Paths	2

Size

Total Lines	11
Code Lines	6

Duplication

Lines	0
Ratio	0 %

Importance

Changes

Metric	Value
cc	2
eloc	6
nc	2
nop	2
dl	0
loc	11
rs	10
c	0
b	0
f	0

<?php

declare(strict_types=1);

/**
 * @copyright Copyright (c) 2016, ownCloud, Inc.
 *
 * @author Andreas Fischer <[email protected]>
 * @author Christoph Wurst <[email protected]>
 * @author Lukas Reschke <[email protected]>
 * @author lynn-stephenson <[email protected]>
 * @author Morris Jobke <[email protected]>
 * @author Roeland Jago Douma <[email protected]>
 *
 * @license AGPL-3.0
 *
 * This code is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License, version 3,
 * as published by the Free Software Foundation.
 *
 * 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 Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License, version 3,
 * along with this program. If not, see <http://www.gnu.org/licenses/>
 *
 */

namespace OC\Security;

use OCP\IConfig;
use OCP\Security\ICrypto;
use OCP\Security\ISecureRandom;
use phpseclib\Crypt\AES;
use phpseclib\Crypt\Hash;

/**
 * Class Crypto provides a high-level encryption layer using AES-CBC. If no key has been provided
 * it will use the secret defined in config.php as key. Additionally the message will be HMAC'd.
 *
 * Usage:
 * $encryptWithDefaultPassword = \OC::$server->getCrypto()->encrypt('EncryptedText');
 * $encryptWithCustompassword = \OC::$server->getCrypto()->encrypt('EncryptedText', 'password');
 *
 * @package OC\Security
 */
class Crypto implements ICrypto {
	/** @var AES $cipher */
	private $cipher;
	/** @var int */
	private $ivLength = 16;
	/** @var IConfig */
	private $config;

	/**
	 * @param IConfig $config
	 * @param ISecureRandom $random
	 */
	public function __construct(IConfig $config) {
		$this->cipher = new AES();
		$this->config = $config;
	}

	/**
	 * @param string $message The message to authenticate
	 * @param string $password Password to use (defaults to `secret` in config.php)
	 * @return string Calculated HMAC
	 */
	public function calculateHMAC(string $message, string $password = ''): string {
		if ($password === '') {
			$password = $this->config->getSystemValue('secret');
		}

		// Append an "a" behind the password and hash it to prevent reusing the same password as for encryption
		$password = hash('sha512', $password . 'a');

		$hash = new Hash('sha512');
		$hash->setKey($password);
		return $hash->hash($message);
	}

	/**
	 * Encrypts a value and adds an HMAC (Encrypt-Then-MAC)
	 * @param string $plaintext
	 * @param string $password Password to encrypt, if not specified the secret from config.php will be taken
	 * @return string Authenticated ciphertext
	 */
	public function encrypt(string $plaintext, string $password = ''): string {
		if ($password === '') {
			$password = $this->config->getSystemValue('secret');
		}
		$keyMaterial = hash_hkdf('sha512', $password);
		$this->cipher->setPassword(substr($keyMaterial, 0, 32));

		$iv = \random_bytes($this->ivLength);
		$this->cipher->setIV($iv);

		$ciphertext = bin2hex($this->cipher->encrypt($plaintext));
		$iv = bin2hex($iv);
		$hmac = bin2hex($this->calculateHMAC($ciphertext.$iv, substr($keyMaterial, 32)));

		return $ciphertext.'|'.$iv.'|'.$hmac.'|3';
	}

	/**
	 * Decrypts a value and verifies the HMAC (Encrypt-Then-Mac)
	 * @param string $authenticatedCiphertext
	 * @param string $password Password to encrypt, if not specified the secret from config.php will be taken
	 * @return string plaintext
	 * @throws \Exception If the HMAC does not match
	 * @throws \Exception If the decryption failed
	 */
	public function decrypt(string $authenticatedCiphertext, string $password = ''): string {
		if ($password === '') {
			$password = $this->config->getSystemValue('secret');
		}
		$hmacKey = $encryptionKey = $password;

		$parts = explode('|', $authenticatedCiphertext);
		$partCount = \count($parts);
		if ($partCount < 3 || $partCount > 4) {
			throw new \Exception('Authenticated ciphertext could not be decoded.');
		}

		$ciphertext = $this->hex2bin($parts[0]);
		$iv = $parts[1];
		$hmac = $this->hex2bin($parts[2]);

		if ($partCount === 4) {
			$version = $parts[3];
			if ($version >= '2') {
				$iv = $this->hex2bin($iv);
			}

			if ($version === '3') {
				$keyMaterial = hash_hkdf('sha512', $password);
				$encryptionKey = substr($keyMaterial, 0, 32);
				$hmacKey = substr($keyMaterial, 32);
			}
		}
		$this->cipher->setPassword($encryptionKey);
		$this->cipher->setIV($iv);

		if (!hash_equals($this->calculateHMAC($parts[0] . $parts[1], $hmacKey), $hmac)) {
			throw new \Exception('HMAC does not match.');
		}

		$result = $this->cipher->decrypt($ciphertext);
		if ($result === false) {

			throw new \Exception('Decryption failed');
		}

		return $result;
	}

	private function hex2bin(string $hex): string {
		if (!ctype_xdigit($hex)) {
			throw new \RuntimeException('String contains non hex chars: ' . $hex);
		}
		if (strlen($hex) % 2 !== 0) {
			throw new \RuntimeException('Hex string is not of even length: ' . $hex);
		}
		$result = hex2bin($hex);

		if ($result === false) {
			throw new \RuntimeException('Hex to bin conversion failed: ' . $hex);
		}

		return $result;
	}
}


1			<?php
2
3			declare(strict_types=1);
4
5			/**
6			* @copyright Copyright (c) 2016, ownCloud, Inc.
7			*
8			* @author Andreas Fischer <[email protected]>
9			* @author Christoph Wurst <[email protected]>
10			* @author Lukas Reschke <[email protected]>
11			* @author lynn-stephenson <[email protected]>
12			* @author Morris Jobke <[email protected]>
13			* @author Roeland Jago Douma <[email protected]>
14			*
15			* @license AGPL-3.0
16			*
17			* This code is free software: you can redistribute it and/or modify
18			* it under the terms of the GNU Affero General Public License, version 3,
19			* as published by the Free Software Foundation.
20			*
21			* This program is distributed in the hope that it will be useful,
22			* but WITHOUT ANY WARRANTY; without even the implied warranty of
23			* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
24			* GNU Affero General Public License for more details.
25			*
26			* You should have received a copy of the GNU Affero General Public License, version 3,
27			* along with this program. If not, see <http://www.gnu.org/licenses/>
28			*
29			*/
30
31			namespace OC\Security;
32
33			use OCP\IConfig;
34			use OCP\Security\ICrypto;
35			use OCP\Security\ISecureRandom;
36			use phpseclib\Crypt\AES;
37			use phpseclib\Crypt\Hash;
38
39			/**
40			* Class Crypto provides a high-level encryption layer using AES-CBC. If no key has been provided
41			* it will use the secret defined in config.php as key. Additionally the message will be HMAC'd.
42			*
43			* Usage:
44			* $encryptWithDefaultPassword = \OC::$server->getCrypto()->encrypt('EncryptedText');
45			* $encryptWithCustompassword = \OC::$server->getCrypto()->encrypt('EncryptedText', 'password');
46			*
47			* @package OC\Security
48			*/
49			class Crypto implements ICrypto {
50			/** @var AES $cipher */
51			private $cipher;
52			/** @var int */
53			private $ivLength = 16;
54			/** @var IConfig */
55			private $config;
56
57			/**
58			* @param IConfig $config
59			* @param ISecureRandom $random
60			*/
61			public function __construct(IConfig $config) {
62			$this->cipher = new AES();
63			$this->config = $config;
64			}
65
66			/**
67			* @param string $message The message to authenticate
68			* @param string $password Password to use (defaults to `secret` in config.php)
69			* @return string Calculated HMAC
70			*/
71			public function calculateHMAC(string $message, string $password = ''): string {
72			if ($password === '') {
73			$password = $this->config->getSystemValue('secret');
74			}
75
76			// Append an "a" behind the password and hash it to prevent reusing the same password as for encryption
77			$password = hash('sha512', $password . 'a');
78
79			$hash = new Hash('sha512');
80			$hash->setKey($password);
81			return $hash->hash($message);
82			}
83
84			/**
85			* Encrypts a value and adds an HMAC (Encrypt-Then-MAC)
86			* @param string $plaintext
87			* @param string $password Password to encrypt, if not specified the secret from config.php will be taken
88			* @return string Authenticated ciphertext
89			*/
90			public function encrypt(string $plaintext, string $password = ''): string {
91			if ($password === '') {
92			$password = $this->config->getSystemValue('secret');
93			}
94			$keyMaterial = hash_hkdf('sha512', $password);
95			$this->cipher->setPassword(substr($keyMaterial, 0, 32));
96
97			$iv = \random_bytes($this->ivLength);
98			$this->cipher->setIV($iv);
99
100			$ciphertext = bin2hex($this->cipher->encrypt($plaintext));
101			$iv = bin2hex($iv);
102			$hmac = bin2hex($this->calculateHMAC($ciphertext.$iv, substr($keyMaterial, 32)));
103
104			return $ciphertext.'\|'.$iv.'\|'.$hmac.'\|3';
105			}
106
107			/**
108			* Decrypts a value and verifies the HMAC (Encrypt-Then-Mac)
109			* @param string $authenticatedCiphertext
110			* @param string $password Password to encrypt, if not specified the secret from config.php will be taken
111			* @return string plaintext
112			* @throws \Exception If the HMAC does not match
113			* @throws \Exception If the decryption failed
114			*/
115			public function decrypt(string $authenticatedCiphertext, string $password = ''): string {
116			if ($password === '') {
117			$password = $this->config->getSystemValue('secret');
118			}
119			$hmacKey = $encryptionKey = $password;
120
121			$parts = explode('\|', $authenticatedCiphertext);
122			$partCount = \count($parts);
123			if ($partCount < 3 \|\| $partCount > 4) {
124			throw new \Exception('Authenticated ciphertext could not be decoded.');
125			}
126
127			$ciphertext = $this->hex2bin($parts[0]);
128			$iv = $parts[1];
129			$hmac = $this->hex2bin($parts[2]);
130
131			if ($partCount === 4) {
132			$version = $parts[3];
133			if ($version >= '2') {
134			$iv = $this->hex2bin($iv);
135			}
136
137			if ($version === '3') {
138			$keyMaterial = hash_hkdf('sha512', $password);
139			$encryptionKey = substr($keyMaterial, 0, 32);
140			$hmacKey = substr($keyMaterial, 32);
141			}
142			}
143			$this->cipher->setPassword($encryptionKey);
144			$this->cipher->setIV($iv);
145
146			if (!hash_equals($this->calculateHMAC($parts[0] . $parts[1], $hmacKey), $hmac)) {
147			throw new \Exception('HMAC does not match.');
148			}
149
150			$result = $this->cipher->decrypt($ciphertext);
151			if ($result === false) {
			0 ignored issues – show introduced 2018-11-14 18:44 UTC by Report Bug Copy Issue Report The condition `$result === false` is always `false`. Loading history...
152			throw new \Exception('Decryption failed');
153			}
154
155			return $result;
156			}
157
158			private function hex2bin(string $hex): string {
159			if (!ctype_xdigit($hex)) {
160			throw new \RuntimeException('String contains non hex chars: ' . $hex);
161			}
162			if (strlen($hex) % 2 !== 0) {
163			throw new \RuntimeException('Hex string is not of even length: ' . $hex);
164			}
165			$result = hex2bin($hex);
166
167			if ($result === false) {
168			throw new \RuntimeException('Hex to bin conversion failed: ' . $hex);
169			}
170
171			return $result;
172			}
173			}
174

nextcloud / server

Push — master ( 634b6b...393309 )

Crypto::calculateHMAC() A

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