add encryption

test/encryption.js

@@ -0,0 +1,21 @@
+'use strict';
+
+const test = require ('ava');
+const crypto = require ('../index');
+
+test ('encryption', (t) => {
+  const enc = crypto.encrypt_aes ('foo', 'bar');
+  t.is (typeof enc, 'string');
+});
+
+test ('decryption', (t) => {
+  const enc = crypto.encrypt_aes ('foo', 'bar');
+  const dec = crypto.decrypt_aes (enc, 'bar');
+  t.is (dec, 'foo');
+});
+
+test ('fail decryption', (t) => {
+  const enc = crypto.encrypt_aes ('foo', 'bar');
+  const dec = crypto.decrypt_aes (enc, 'baz');
+  t.is (dec, null);
+});