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Diffstat (limited to 'src')
| -rw-r--r-- | src/lib.rs | 185 |
1 files changed, 185 insertions, 0 deletions
diff --git a/src/lib.rs b/src/lib.rs new file mode 100644 index 000000000000..a7638c524643 --- /dev/null +++ b/src/lib.rs @@ -0,0 +1,185 @@ +//! Implements a library for verifying JSON Web Tokens using the +//! `RS256` signature algorithm. +//! +//! This library is specifically aimed at developers that consume +//! tokens from services which provide their RSA public keys in +//! [JWKS][] format. +//! +//! ## Usage example (token with `kid`-claim) +//! +//! ```rust +//! 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); +//! } +//! }, +//! } +//! } +//! ``` +//! +//! [JWKS]: https://tools.ietf.org/html/rfc7517 + +#[macro_use] extern crate serde_derive; + +extern crate base64; +extern crate openssl; +extern crate serde; +extern crate serde_json; + +use base64::{decode_config, URL_SAFE}; +use openssl::bn::BigNum; +use openssl::pkey::Public; +use openssl::rsa::{Rsa}; + +/// JWT algorithm used. The only supported algorithm is currently +/// RS256. +#[derive(Deserialize, Debug)] +enum KeyAlgorithm { RS256 } + +/// Type of key contained in a JWT. The only supported key type is +/// currently RSA. +#[derive(Deserialize, Debug)] +enum KeyType { RSA } + +/// Representation of a single JSON Web Key. See [RFC +/// 7517](https://tools.ietf.org/html/rfc7517#section-4). +#[derive(Deserialize)] +pub struct JWK { + kty: KeyType, + alg: Option<KeyAlgorithm>, + kid: Option<String>, + + // Shared modulus + n: String, + + // Public key exponent + e: String, +} + +/// Representation of a collection ("set") of JSON Web Keys. See +/// [RFC 7517](https://tools.ietf.org/html/rfc7517#section-5). +pub struct JWKS { + // This is a vector instead of some kind of map-like structure + // because key IDs are in fact optional. + // + // Technically having multiple keys with the same KID would not + // violate the JWKS-definition either, but behaviour in that case + // is unspecified. + keys: Vec<JWK>, +} + +impl JWKS { + /// Attempt to find a JWK by its key ID. + pub fn find(&self, kid: &str) -> Option<&JWK> { + self.keys.iter().find(|jwk| jwk.kid == Some(kid.into())) + } +} + +/// Representation of a JSON Web Token. See [RFC +/// 7519](https://tools.ietf.org/html/rfc7519). +pub struct JWT {} + +/// Possible token claim validations. This enumeration only covers +/// common use-cases, for other types of validations the user is +/// encouraged to inspect the claim set manually. +pub enum Validation {} + +/// Possible results of a token validation. +pub enum ValidationResult { + /// Signature and claim validation succeeded. + Valid, + + /// Decoding of the provided JWK failed. + InvalidJWK(String), + + /// Signature validation failed, i.e. because of a non-matching + /// public key. + InvalidSignature, + + /// One or more claim validations failed. + // TODO: Provide reasons? + InvalidClaims, +} + +/// Attempt to extract the `kid`-claim out of a JWT's header claims. +/// +/// This function is normally used when a token provider has multiple +/// public keys in rotation at the same time that could all still have +/// valid tokens issued under them. +/// +/// This is only safe if the key set containing the currently allowed +/// key IDs is fetched from a trusted source. +pub fn token_kid(jwt: JWT) -> Option<String> { + unimplemented!() +} + +/// Validate the signature of a JSON Web Token and optionally apply +/// claim validations. Signatures are always verified before claims, +/// and if a signature verification passes *all* claim validations are +/// run and returned. +/// +/// It is the user's task to ensure that the correct JWK is passed in +/// for validation. +pub fn validate(jwt: JWT, jwk: JWK, validations: Vec<Validation>) -> ValidationResult { + unimplemented!() +} + +// Internal implementation +// +// The functions in the following section are not part of the public +// API of this library. + +/// Decode a single key fragment to an OpenSSL BigNum. +fn decode_fragment(fragment: &str) -> Option<BigNum> { + let bytes = decode_config(fragment, URL_SAFE).ok()?; + BigNum::from_slice(&bytes).ok() +} + +/// Decode an RSA public key from a JWK by constructing it directly +/// from the public RSA key fragments. +fn public_key_from_jwk(jwk: &JWK) -> Option<Rsa<Public>> { + let jwk_n = decode_fragment(&jwk.n)?; + let jwk_e = decode_fragment(&jwk.e)?; + Rsa::from_public_components(jwk_n, jwk_e).ok() +} + +#[cfg(test)] +mod tests { + use super::*; + + #[test] + fn test_fragment_decoding() { + let fragment = "ngRRjNbXgPW29oNtF0JgsyyfTwPyEL0u_X16s453X2AOc33XGFxVKLEQ7R_TiMenaKcr-tPifYqgps_deyi0XOr4I3SOdOMtAVKDZJCANe--CANOHZb-meIfjKhCHisvT90fm5Apd6qPRVsXsZ7A8pmClZHKM5fwZUkBv8NsPLm2Xy2sGOZIiwP_7z8m3j0abUzniPQsx2b3xcWimB9vRtshFHN1KgPUf1ALQ5xzLfJnlFkCxC7kmOxKC7_NpQ4kJR_DKzKFV_r3HxTqf-jddHcXIrrMcLQXCSyeLQtLaz7whQ4F-EfL42z4XgwPr4ji3sct2gWL13EqlbE5DDxLKQ"; + let bignum = decode_fragment(fragment).expect("Failed to decode fragment"); + + let expected = "19947781743618558124649689124245117083485690334420160711273532766920651190711502679542723943527557680293732686428091794139998732541701457212387600480039297092835433997837314251024513773285252960725418984381935183495143908023024822433135775773958512751261112853383693442999603704969543668619221464654540065497665889289271044207667765128672709218996183649696030570183970367596949687544839066873508106034650634722970893169823917299050098551447676778961773465887890052852528696684907153295689693676910831376066659456592813140662563597179711588277621736656871685099184755908108451080261403193680966083938080206832839445289"; + assert_eq!(expected, format!("{}", bignum), "Decoded fragment should match "); + } +} |