diff --git a/src/Utils/KeyCrypt.php b/src/Utils/KeyCrypt.php
new file mode 100644
index 00000000..d5e5e2c4
--- /dev/null
+++ b/src/Utils/KeyCrypt.php
@@ -0,0 +1,81 @@
+<?php
+/**
+ * Public/private key encryption
+ *
+ * @package     league/oauth2-server
+ * @author      Alex Bilbie <hello@alexbilbie.com>
+ * @copyright   Copyright (c) Alex Bilbie
+ * @license     http://mit-license.org/
+ * @link        https://github.com/thephpleague/oauth2-server
+ */
+
+namespace League\OAuth2\Server\Utils;
+
+class KeyCrypt
+{
+    /**
+     * Encrypt data with a private key
+     *
+     * @param string $unencryptedData
+     * @param string $pathToPrivateKey
+     *
+     * @return string
+     */
+    public static function encrypt($unencryptedData, $pathToPrivateKey)
+    {
+        $privateKey = openssl_pkey_get_private($pathToPrivateKey);
+        $privateKeyDetails = @openssl_pkey_get_details($privateKey);
+        if ($privateKeyDetails === null) {
+            throw new \LogicException(sprintf('Could not get details of private key: %s', $pathToPrivateKey));
+        }
+
+        $chunkSize = ceil($privateKeyDetails['bits'] / 8) - 11;
+        $output = '';
+
+        while ($unencryptedData) {
+            $chunk = substr($unencryptedData, 0, $chunkSize);
+            $unencryptedData = substr($unencryptedData, $chunkSize);
+            if (openssl_private_encrypt($chunk, $encrypted, $privateKey) === false) {
+                throw new \LogicException('Failed to encrypt data');
+            }
+            $output .= $encrypted;
+        }
+        openssl_free_key($privateKey);
+
+        return base64_encode($output);
+    }
+
+    /**
+     * Decrypt data with a public key
+     *
+     * @param string $encryptedData
+     * @param string $pathToPublicKey
+     *
+     * @return string
+     */
+    public static function decrypt($encryptedData, $pathToPublicKey)
+    {
+        $publicKey = openssl_pkey_get_public($pathToPublicKey);
+        $publicKeyDetails = @openssl_pkey_get_details($publicKey);
+        if ($publicKeyDetails === null) {
+            throw new \LogicException(sprintf('Could not get details of public key: %s', $pathToPublicKey));
+        }
+
+        $chunkSize = ceil($publicKeyDetails['bits'] / 8);
+        $output = '';
+
+        $encryptedData = base64_decode($encryptedData);
+
+        while ($encryptedData) {
+            $chunk = substr($encryptedData, 0, $chunkSize);
+            $encryptedData = substr($encryptedData, $chunkSize);
+            if (openssl_public_decrypt($chunk, $decrypted, $publicKey) === false) {
+                throw new \LogicException('Failed to decrypt data');
+            }
+            $output .= $decrypted;
+        }
+        openssl_free_key($publicKey);
+
+        return $output;
+    }
+}