According to Wikipedia: “Encryption is the process of encoding messages or information in such a way that only authorized parties can read it. Encryption does not of itself prevent interception, but denies the message content to the interceptor. In an encryption scheme, the message or information, referred to as plaintext, is encrypted using an encryption algorithm, generating ciphertext that can only be read if decrypted.”
All WPESignature documents, drawn signatures, input fields (radio buttons, text fields, checkboxes, etc) and document content is encrypted and stored in your database.
If a user were to login to their phpmyadmin database and pull up a database table what they would see is something like this: