How do I make private docs alongside public docs in a CouchDB database? - authentication

Question

I'm somewhat new to CouchDB and I'm wondering how to make private docs, that is I want to have a database where all docs are public (rw, or r using a validate_doc_update) except for few/some selected docs, how would I do something like that?
And to complicate things a bit more I want them to be private to / accessible by the admin but also varying number of selected users (but no others).
I'm thinking that perhaps I could have two keys in these docs called "private" and "private_users", set them to true and [user1, user2, user3], and somehow use that info to make the docs private / only accessible by them.
So essentially it's about users being able to create docs and have them visible to everybody or just themselves and other selected users.
One way to do this would be to make the database private by setting the Security admin and members lists to the owner (making the database completely private), and then route all calls to reading documents through a backend script which checks these properties of the document through an admin account and fetches and returns the content if conditions are met, but the thing is I'd like to do this through configuring CouchDB and do CORS HTTPS calls from the clients browser directly to CouchDB, with no script in the middle.
Is this possible?

Answer 1

There are several potential solutions to this problem:
The problem: For a given user, allow only specific access to a given document in the database.
Database per user:
Create one database for each user and use authentication on the database for that given user. Because views do not work across databases, you will have to replicate all needed data between the different user databases to allow for a view to contain both private and public/other users' data. Because normal users can not create/delete databases, you will need to have a separate process running which watches your database for changes and creates a new user database when a new user registers.
Smart Proxy:
Create a smart proxy that wraps all documents with the user credentials and filters all results.
Document Encryption on a per User Basis:
This solution is described in a google document which was mentioned on the development mailinglist. The goal of this solution is to create a P2P like system, where you can replicate data to nodes which you don't trust.
validate_read_doc:
Have a javascript function be called on every read, in the same manner as the validate_doc_update system is applied.
For more information:
http://wiki.apache.org/couchdb/PerDocumentAuthorization

Answer 2

So essentially it's about users being able to create docs and have them visible to everybody or just themselves and other selected users ...... Is this possible?
Not with just couchdb...
The permissions that you set with _security in a database only apply write level security on it.
Other wise most of the documents (except the design documents) are available for every one to read. With validate functions
you can impose further restrictions on who writes the documents but again there is no way to check who is reading your documents.
rcouch has a validation on read which can help you what you want to do. Other wise if you want to go with couchdb you could use a proxy for communicating with it.