We LOVE security! If you don’t know that already, you soon will. 🙂 We’re passionate about the subject and always looking for ways to improve the security of WP E-Signature.
One of the (many) security features we use is encryption. You can read more about that here if you’re interested.
But if you are viewing this support page it is likely because Mcrypt is not enabled on your server.
You will likely need to contact your web host and request that they enable this feature.
Here is a helpful article that explains how to set it up.