bitset

bitset

A simple bit set with JSON support

Motivation

The package built specially for usage in JWT tokens in package github.com/axkit/aaa

Concepts

• Application functionality can be limited by using permissions.
• Permission (access right) represented by unique string code.
• Application can have 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 succesfull sign in backend provides access and resresh tokens.
• Payload of access token shall 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 accociated with a single bit in the set.
• Bitset adds to the token as hexadecimal string.

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"

Check allowed permission in auth middleware

    ...
    tokenPerms := accessToken.Payload.Perms     // "0605
    bs := 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