bitset

A simple bit set with JSON support

Motivation

The package built specially to be used in package github.com/axkit/aaa as a JWT permissions holder but can be used independently.

Concepts

• Application functionality can be limited by using permissions.
• Permission (access right) represented by unique string code.
• Application supports many permissions.
• A user has a role.
• A role is set of allowed permission, it's subset of all permissions supported by application.
• As a result of successful sign in, a backend provides access and refresh tokens.
• The payload of access token have list of allowed permissions.
• A single permission code looks like "Customers.Create", "Customer.AttachDocuments", "Customer.Edit", etc.
• Store allowed permission codes could increase token size.
• Bitset comes here.
• Every permission shall be associated with a single bit in the set.
• Bitset adds to the token as hexadecimal string. Every 8 permissions represented by 2 characters.

Usage Examples

Sign In

    var perms bitset.Bitset
    perms.Set(1)                    // 0000_0010
    perms.Set(2)                    // 0000_0110
    perms.Set(8, 10)                // 0000_0110 0000_0101
    tokenPerms := perms.String()    // returns "0605" as hex representation of 0000_0110 0000_0101

Check allowed permission in auth middleware

    ...
    tokenPerms := accessToken.Payload.Perms     // "0605"
    bs, err := bitset.Parse(tokenPerms)         // returns 0000_0110 0000_0101
    if bs.AreSet(2,8) {
        // the permission allowed
    }

Further Improvements

• Finalize integration BitSet with database/sql
• Add benchmarks
• Reduce memory allocations

Prague 2020