Make mcrypt optional

Now Security::encrypt() and Security::decrypt() works with openssl
if the mcrypt extension is unavailable.
Note that Security::rijndael() doesn't work with openssl.

composer.json

@@ -18,8 +18,11 @@
 		"source": "https://github.com/cakephp/cakephp"
 	},
 	"require": {
-		"php": ">=5.3.0",
+		"php": ">=5.3.0"
-		"ext-mcrypt": "*"
+	},
+	"suggest": {
+		"ext-openssl": "You need to install ext-openssl or ext-mcrypt to use AES-256 encryption",
+		"ext-mcrypt": "You need to install ext-openssl or ext-mcrypt to use AES-256 encryption"
 	},
 	"require-dev": {
 		"phpunit/phpunit": "<6.0.0",

lib/Cake/Test/Case/Utility/SecurityTest.php

@@ -29,6 +29,45 @@ class SecurityTest extends CakeTestCase {
  */
 	public $sut = null;
 
+/**
+ * setUp method
+ *
+ * @return void
+ */
+	public function setUp() {
+		parent::setUp();
+		Security::engine(null);
+	}
+
+/**
+ * tearDown method
+ *
+ * @return void
+ */
+	public function tearDown() {
+		parent::tearDown();
+		Security::engine(null);
+	}
+
+/**
+ * Tests that Security::engine() works
+ *
+ * @return void
+ */
+	public function testEngine() {
+		if (extension_loaded('mcrypt')) {
+			$this->assertEquals('mcrypt', Security::engine());
+		}
+
+		$this->assertContains(Security::engine(), array('mcrypt', 'openssl'));
+
+		Security::engine('mcrypt');
+		$this->assertEquals('mcrypt', Security::engine());
+
+		Security::engine('openssl');
+		$this->assertEquals('openssl', Security::engine());
+	}
+
 /**
  * testInactiveMins method
  *
@@ -337,6 +376,54 @@ class SecurityTest extends CakeTestCase {
 		$this->assertEquals($txt, Security::decrypt($result, $key));
 	}
 
+/**
+ * Tests that encrypted strings are comatible between the mcrypt and openssl engine.
+ *
+ * @dataProvider plainTextProvider
+ * @param string $txt Plain text to be encrypted.
+ * @return void
+ */
+	public function testEncryptDecryptCompatibility($txt) {
+		$this->skipIf(!extension_loaded('mcrypt'), 'This test requires mcrypt to be installed');
+		$this->skipIf(!extension_loaded('openssl'), 'This test requires oepnssl to be installed');
+		$this->skipIf(version_compare(PHP_VERSION, '5.3.3', '<'), 'This test requires PHP 5.3.3 or grater');
+
+		$key = '12345678901234567890123456789012';
+
+		Security::engine('mcrypt');
+		$mcrypt = Security::encrypt($txt, $key);
+
+		Security::engine('openssl');
+		$openssl = Security::encrypt($txt, $key);
+
+		$this->assertEquals(strlen($mcrypt), strlen($openssl));
+
+		Security::engine('mcrypt');
+		$this->assertEquals($txt, Security::decrypt($mcrypt, $key));
+		$this->assertEquals($txt, Security::decrypt($openssl, $key));
+
+		Security::engine('openssl');
+		$this->assertEquals($txt, Security::decrypt($mcrypt, $key));
+		$this->assertEquals($txt, Security::decrypt($openssl, $key));
+	}
+
+/**
+ * Data provider for testEncryptDecryptCompatibility
+ *
+ * @return array
+ */
+	public function plainTextProvider() {
+		return array(
+			array(''),
+			array('abcdefg'),
+			array('1234567890123456'),
+			array('The quick brown fox'),
+			array('12345678901234567890123456789012'),
+			array('The quick brown fox jumped over the lazy dog.'),
+			array('何らかのマルチバイト文字列'),
+		);
+	}
+
 /**
  * Test that changing the key causes decryption to fail.
  *

lib/Cake/Utility/Security.php

@@ -25,6 +25,13 @@ App::uses('CakeText', 'Utility');
  */
 class Security {
 
+/**
+ * The encryption engine
+ *
+ * @var string
+ */
+	protected static $_engine = null;
+
 /**
  * Default hash method
  *
@@ -206,7 +213,7 @@ class Security {
  * for sensitive data. Additionally this method does *not* work in environments
  * where suhosin is enabled.
  *
- * Instead you should use Security::rijndael() when you need strong
+ * Instead you should use Security::encrypt() when you need strong
  * encryption.
  *
  * @param string $text Encrypted string to decrypt, normal string to encrypt
@@ -349,12 +356,24 @@ class Security {
 		// Generate the encryption and hmac key.
 		$key = substr(hash('sha256', $key . $hmacSalt), 0, 32);
 
+		if (static::engine() === 'openssl') {
+			$method = 'AES-256-CBC';
+			$ivSize = openssl_cipher_iv_length($method);
+			$iv = openssl_random_pseudo_bytes($ivSize);
+			$padLength = (int)ceil((strlen($plain) ?: 1) / $ivSize) * $ivSize;
+			$ciphertext = openssl_encrypt(str_pad($plain, $padLength, "\0"), $method, $key, true, $iv);
+			// Remove the PKCS#7 padding block for compatibility with mcrypt.
+			// Since we have padded the provided data with \0, the final block contains only padded bytes.
+			// So it can be removed safely.
+			$ciphertext = $iv . substr($ciphertext, 0, -$ivSize);
+		} else {
 			$algorithm = MCRYPT_RIJNDAEL_128;
 			$mode = MCRYPT_MODE_CBC;
-
 			$ivSize = mcrypt_get_iv_size($algorithm, $mode);
 			$iv = mcrypt_create_iv($ivSize, MCRYPT_DEV_URANDOM);
 			$ciphertext = $iv . mcrypt_encrypt($algorithm, $key, $plain, $mode, $iv);
+		}
+
 		$hmac = hash_hmac('sha256', $ciphertext, $key);
 		return $hmac . $ciphertext;
 	}
@@ -404,14 +423,42 @@ class Security {
 			return false;
 		}
 
+		if (static::engine() === 'openssl') {
+			$method = 'AES-256-CBC';
+			$ivSize = openssl_cipher_iv_length($method);
+			$iv = substr($cipher, 0, $ivSize);
+			$cipher = substr($cipher, $ivSize);
+			// Regenerate PKCS#7 padding block
+			$padding = openssl_encrypt('', $method, $key, true, substr($cipher, -$ivSize));
+			$plain = openssl_decrypt($cipher . $padding, $method, $key, true, $iv);
+		} else {
 			$algorithm = MCRYPT_RIJNDAEL_128;
 			$mode = MCRYPT_MODE_CBC;
 			$ivSize = mcrypt_get_iv_size($algorithm, $mode);
-
 			$iv = substr($cipher, 0, $ivSize);
 			$cipher = substr($cipher, $ivSize);
 			$plain = mcrypt_decrypt($algorithm, $key, $cipher, $mode, $iv);
+		}
+
 		return rtrim($plain, "\0");
 	}
 
+/**
+ * Set or get the encryption engine
+ *
+ * @param string $engine The encryption engine to use
+ * @return string
+ */
+	public static function engine($engine = null) {
+		if (func_num_args() > 0) {
+			static::$_engine = $engine;
+		} elseif (static::$_engine === null) {
+			static::$_engine = 'mcrypt';
+			if (!extension_loaded('mcrypt') && extension_loaded('openssl') && version_compare(PHP_VERSION, '5.3.3', '>=')) {
+				static::$_engine = 'openssl';
+			}
+		}
+		return static::$_engine;
+	}
+
 }