alcoholic_jwt

This is a barebones library for validation of RS256 JWTs using keys from a JWKS. Nothing more, nothing less.

The name of the library stems from the potential side-effects of trying to use the other Rust libraries that are made for similar purposes.

Usage overview

You are retrieving JWTs from some authentication provider that uses RS256 signatures and provides its public keys in JWKS format.

Example for a token that provides the key ID used for signing in the kid claim:

extern crate alcoholic_jwt;

use alcoholic_jwt::{JWKS, Validation, validate, token_kid};

fn validate_token() {
    // serde instances provided
    let jwks: JWKS = some_http_client(jwks_url).json();

    let token: String = some_token_fetcher();

    // Several types of built-in validations are provided:
    let validations = vec![
      Validation::Issuer("some-issuer"),
      Validation::Audience("some-audience"),
      Validation::SubjectPresent,
    ];

    // Extracting a KID is about the only safe operation that can be
    // done on a JWT before validating it.
    let kid = token_kid(token).expect("No 'kid' claim present in token");

    let jwk = jwks.find(kid).expect("Specified key not found in set");

    match validate(token, jwk, validations) {
      Valid => println!("Token is valid!"),
      InvalidSignature(reason) => println!("Token signature invalid: {}", reason),
      InvalidClaims(reasons) => {
          println!("Token claims are totally invalid!");
          for reason in reasons {
              println!("Validation failure: {}", reason);
          }
      },
    }
}

Under the hood

This library aims to only use trustworthy off-the-shelf components to do the work. Cryptographic operations are provided by the openssl crate, JSON-serialisation is provided by serde_json.