You can use GUN with a schema system to enforce/validate data ( https://github.com/gundb/gun-schema ), and it looks like the author of that module made it work server side in NodeJS - meaning you can have enforcement/validation at every point.
Canonical data may be a bit tricky, to do this correctly you need to sign the data. Then you can check the signature of the data against the canonical public key.
Permissions on read/write, this is not much different than any other database like MongoDB or MySQL. If you want to authorize read/writes, you need to proxy it through an authorized server which can authenticate the read/write requests. Very few databases actually have auth built in.
If you have any more questions, please jump on the https://gitter.im/amark/gun and we’d be happy to help!
