Description

The validator client does not store the messages it signs and is therefore vulnerable to generating slashable messages

Steps to resolve

• Determine a suitable database format.
• Ensure all signed messages are stored in the database.
• Ensure that newly signed messages are not in conflict with any previously signed messages.

Additional Info

Database formats

We want this database to be validator specific and portable. For example, I want to be able to move my validator from one machine to another, whilst maintaining that validators message history. As such, I suggest each validator has their own database, stored alongside their keys and config info (see #253 for suggestions on directory structure).

We should choose some single-process database that has high resistance to corruption.