diff --git a/.cache/.git_keep b/.cache/.git_keep
new file mode 100644
index 0000000..e69de29
diff --git a/lib/crypto.php b/lib/crypto.php
new file mode 100644
index 0000000..f039960
--- /dev/null
+++ b/lib/crypto.php
@@ -0,0 +1,31 @@
+<?php
+declare(strict_types=1);
+
+namespace SCCP\Crypto;
+
+class HashAlgo // extends Enum 
+{
+    private const SHA1 = 0;
+    private const SHA256 = 1;
+}
+
+class Certificate {
+    function __construct(string $file) {
+		$this->file = $file;
+    }
+    
+    public function hashAsBase64(int $hashAlg)  : string  {
+        return "";
+    }
+}
+
+class Crypto {
+
+    public static function certificateHashAsBase64(string $certificateFile, int $hashAlg)  : string  {
+        return new Certificate($certificateFile)
+                .hashAsBase64($hashAlg);
+    }
+}
+
+class Signer {
+}
diff --git a/lib/resolver.php b/lib/resolver.php
index 5d60147..2bdaef5 100644
--- a/lib/resolver.php
+++ b/lib/resolver.php
@@ -1,5 +1,6 @@
 <?php
 declare(strict_types=1);
+
 namespace SCCP\Resolve;
 include_once("config.php");
 include_once("utils.php");