diff --git a/.gitignore b/.gitignore
index c85804c..e5c296b 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,2 +1,4 @@
 /node_modules/
-/dist/
\ No newline at end of file
+/dist/
+/.nyc_output/
+/coverage/
diff --git a/package.json b/package.json
index 19ccfd7..53171d6 100644
--- a/package.json
+++ b/package.json
@@ -14,5 +14,8 @@
     "lint": "eslint .",
     "test": "nyc ava",
     "ci": "yarn && node jenkins.js"
+  },
+  "dependencies": {
+    "@scode/encoding-helper": "^1.0.1"
   }
-}
\ No newline at end of file
+}
diff --git a/test/index.js b/test/index.js
new file mode 100644
index 0000000..c47e800
--- /dev/null
+++ b/test/index.js
@@ -0,0 +1,111 @@
+/*
+ * Copyright (C) Sapphirecode - All Rights Reserved
+ * Created by Timo Hocker <timo@scode.ovh>, March 2020
+ */
+
+/* eslint-disable no-magic-numbers */
+// @ts-nocheck
+'use strict';
+
+const test = require ('ava');
+const crypto = require ('../index');
+
+test ('random_hex', (t) => {
+  const hex = crypto.random_hex (16);
+  t.is (hex.length, 16);
+  t.regex (hex, /^[0-9a-f]+$/iu);
+});
+
+test ('random_hex with default length', (t) => {
+  const hex = crypto.random_hex ();
+  t.is (hex.length, 8);
+  t.regex (hex, /^[0-9a-f]+$/iu);
+});
+
+test ('random_hex should refuse lenght smaller 1', (t) => {
+  t.throws (() => (crypto.random_hex (0)));
+});
+
+test ('random_string', (t) => {
+  const str = crypto.random_string (16);
+  t.is (str.length, 16);
+});
+
+test ('random_string with default length', (t) => {
+  const str = crypto.random_string ();
+  t.is (str.length, 8);
+});
+
+test ('random_string should refuse lenght smaller 1', (t) => {
+  t.throws (() => (crypto.random_string (0)));
+});
+
+test ('hash_sha512', (t) => {
+  const hash = crypto.hash_sha512 ('a', 'b');
+  t.is (
+    hash,
+    // eslint-disable-next-line max-len
+    '2d408a0717ec188158278a796c689044361dc6fdde28d6f04973b80896e1823975cdbf12eb63f9e0591328ee235d80e9b5bf1aa6a44f4617ff3caf6400eb172d'
+  );
+});
+
+test ('checksum', (t) => {
+  const hash = crypto.checksum ('foo');
+  t.is (
+    hash,
+    // eslint-disable-next-line max-len
+    '2c26b46b68ffc68ff99b453c1d30413413422d706483bfa0f98a5e886266e7ae'
+  );
+});
+
+test ('create_salt', (t) => {
+  const salt = crypto.create_salt ();
+  t.is (salt.length, 64);
+  t.regex (salt, /^[0-9a-f]+$/iu);
+});
+
+test ('sign_object', (t) => {
+  const obj = { foo: 'bar' };
+  t.notThrows (() => {
+    const str = crypto.sign_object (obj, 'baz');
+    t.is (typeof str, 'string');
+  });
+});
+
+test ('decode_signed', (t) => {
+  const obj = { foo: 'bar' };
+  const str = crypto.sign_object (obj, 'baz');
+  const dec = crypto.decode_signed (str);
+  t.deepEqual (obj, dec);
+});
+
+test ('verify_signature', (t) => {
+  const obj = { foo: 'bar' };
+  const str = crypto.sign_object (obj, 'baz');
+  const dec = crypto.verify_signature (str, 'baz');
+  t.deepEqual (obj, dec);
+});
+
+test ('reject tampered signatures', (t) => {
+  const obj = { foo: 'bar' };
+  const str = crypto.sign_object (obj, 'baz');
+  const dec = crypto.verify_signature (str, 'foo');
+  t.is (dec, null);
+});
+
+test ('reject old signatures', async (t) => {
+  const obj = { foo: 'bar' };
+  const str = crypto.sign_object (obj, 'baz');
+  await new Promise ((res) => {
+    setTimeout (res, 10);
+  });
+  const dec = crypto.verify_signature (str, 'baz', 1);
+  t.is (dec, null);
+});
+
+test ('decode problematic token', (t) => {
+  // eslint-disable-next-line max-len
+  const str = 'eyJpYXQiOjE1ODE0NDAwMTIyODgsIm9iaiI6eyJpZCI6MX19.24ZOsWrnfkNe%2FbM0r7DaVJMqE2bfn2aAM%2BZSzWeSf31OCTlXXNWD34RBL2X5v3UliYQ4IIsLNBFbaW9texPHug%3D%3D';
+  const obj = crypto.decode_signed (str);
+  t.deepEqual (obj, { id: 1 });
+});
diff --git a/yarn.lock b/yarn.lock
index 09dbffa..7c4f431 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -162,6 +162,11 @@
     "@nodelib/fs.scandir" "2.1.3"
     fastq "^1.6.0"
 
+"@scode/encoding-helper@^1.0.1":
+  version "1.0.1"
+  resolved "https://npm.scode.ovh/@scode%2fencoding-helper/-/encoding-helper-1.0.1.tgz#dfac0f5f8ae6060c5305575ae7229e05365fa518"
+  integrity sha512-EZiNDnvcbAsnbtb81Ypz7j0QUsmtfNlSVOkXOvDqEqJNfsrFr+e/5IvQJH8TPP0Iwzu9etbHXhEzRg6eOStGng==
+
 "@scode/eslint-config@^1.2.25":
   version "1.2.25"
   resolved "https://npm.scode.ovh/@scode%2feslint-config/-/eslint-config-1.2.25.tgz#b126e2e23ecf418c66e634fa279fd0e8e06ab4db"