Switch to OpenSSL (mcrypt deprecated in PHP 7.1)

Author: leith

composer.json

@@ -38,7 +38,7 @@
         "squizlabs/php_codesniffer": "^3.5"
     },
     "suggest": {
-        "ext-mcrypt": "Required for hashing functions to check message signatures"
+        "ext-openssl": "Required for hashing functions to check message signatures"
     },
     "extra": {
         "branch-alias": {

src/Message/Security.php

@@ -58,7 +58,11 @@ protected function encryptMessage($message, $key)
         $iv = implode(array_map('chr', array(0, 0, 0, 0, 0, 0, 0, 0)));
 
         if ($this->hasValidEncryptionMethod()) {
-            $ciphertext = mcrypt_encrypt(MCRYPT_3DES, $key, $message, MCRYPT_MODE_CBC, $iv);
+            // OpenSSL needs to manually pad $message length to be mod 8 = 0; OPENSSL_ZERO_PADDING option doens't work
+            if (strlen($message) % 8) {
+                $message = str_pad($message, strlen($message) + 8 - strlen($message) % 8, "\0");
+            }
+            $ciphertext = openssl_encrypt($message, 'des-ede3-cbc', $key, OPENSSL_RAW_DATA | OPENSSL_NO_PADDING, $iv);
         } else {
             throw new RuntimeException('No valid encryption extension installed');
         }
@@ -73,7 +77,7 @@ protected function encryptMessage($message, $key)
      */
     public function hasValidEncryptionMethod()
     {
-        return extension_loaded('mcrypt') && function_exists('mcrypt_encrypt');
+        return extension_loaded('openssl') && function_exists('openssl_encrypt');
     }
 
     /**

tests/Message/SecurityTest.php

@@ -38,14 +38,14 @@ public function testDecodeMerchantParameters()
     }
 
     /**
-     * Confirm that the mcrypt extension is loaded and we have the appropriate method
+     * Confirm that the openssl extension is loaded and we have the appropriate method
      *
      * Checks are split out in case only one is failing, rather than the blanket true/false for both
      */
     public function testHasValidEncryptionMethod()
     {
-        $this->assertTrue(extension_loaded('mcrypt'));
-        $this->assertTrue(function_exists('mcrypt_encrypt'));
+        $this->assertTrue(extension_loaded('openssl'));
+        $this->assertTrue(function_exists('openssl_encrypt'));
         $this->assertTrue($this->security->hasValidEncryptionMethod());
     }