MAGETWO-67319: Add @api Annotation in Encryption framework library

Author: buskamuza

lib/internal/Magento/Framework/Encryption/Crypt.php

@@ -4,12 +4,12 @@
  * See COPYING.txt for license details.
  */
 
-// @codingStandardsIgnoreFile
-
 namespace Magento\Framework\Encryption;
 
 /**
  * Class encapsulates cryptographic algorithm
+ *
+ * @api
  */
 class Crypt
 {
@@ -85,8 +85,6 @@ public function __construct($key, $cipher = MCRYPT_BLOWFISH, $mode = MCRYPT_MODE
 
     /**
      * Destructor frees allocated resources
-     *
-     * @return void
      */
     public function __destruct()
     {

lib/internal/Magento/Framework/Encryption/EncryptorInterface.php

@@ -7,6 +7,8 @@
 
 /**
  * Encryptor interface
+ *
+ * @api
  */
 interface EncryptorInterface
 {

lib/internal/Magento/Framework/Encryption/Helper/Security.php

@@ -4,18 +4,20 @@
  * See COPYING.txt for license details.
  */
 
-// @codingStandardsIgnoreFile
-
 namespace Magento\Framework\Encryption\Helper;
 
 use Zend\Crypt\Utils;
 
 /**
  * Class implements compareString from Zend\Crypt
+ *
+ * @api
  */
 class Security
 {
     /**
+     * Compare two strings in a secure way that avoids string length guessing based on duration of calculation
+     *
      * @param  string $expected
      * @param  string $actual
      * @return bool

lib/internal/Magento/Framework/Encryption/UrlCoder.php

@@ -6,6 +6,9 @@
  */
 namespace Magento\Framework\Encryption;
 
+/**
+ * @api
+ */
 class UrlCoder
 {
     /**