A new JWT (JSON Web Tokens) implementation for Rust that focuses on simplicity, while avoiding common JWT security pitfalls.
jwt-simple is unopinionated and supports all commonly deployed authentication and signature algorithms:
| JWT algorithm name | Description |
| ------------------ | ------------------------------------- |
| HS256 | HMAC-SHA-256 |
| HS384 | HMAC-SHA-384 |
| HS512 | HMAC-SHA-512 |
| RS256 | RSA with PKCS#1v1.5 padding / SHA-256 |
| RS384 | RSA with PKCS#1v1.5 padding / SHA-384 |
| RS512 | RSA with PKCS#1v1.5 padding / SHA-512 |
| PS256 | RSA with PSS padding / SHA-256 |
| PS384 | RSA with PSS padding / SHA-384 |
| PS512 | RSA with PSS padding / SHA-512 |
| ES256 | ECDSA over p256 / SHA-256 |
| ES256K | ECDSA over secp256k1 / SHA-256 |
| EdDSA | Ed25519 |
jwt-simple uses only pure Rust implementations, and can be compiled out of the box to WebAssembly/WASI. It is fully compatible with Fastly's Compute@Edge service.
Important: JWT's purpose is to verify that data has been created by a party knowing a secret key. It does not provide any kind of confidentiality: JWT data is simply encoded as BASE64, and is not encrypted.
cargo.toml:
toml
[dependencies]
jwt-simple = "0.1"
Rust:
rust
use jwt_simple::prelude::*;
HS* JWT algorithms) exampleAuthentication schemes use the same key for creating and verifying tokens. In other words, both parties need to ultimately trust each other, or else the verifier could also create arbitrary tokens.
Key creation:
```rust use jwt_simple::prelude::*;
// create a new key for the HS256 JWT algorithm
let key = HS256Key::generate();
```
A key can be exported as bytes with key.to_bytes(), and restored with HS256Key::from_bytes().
Token creation:
rust
/// create claims valid for 2 hours
let claims = Claims::create(Duration::from_hours(2));
let token = key.authenticate(claims)?;
-> Done!
rust
let claims = key.verify_token::<NoCustomClaims>(&token, None)?;
-> Done! No additional steps required.
Key expiration, start time, authentication tags, etc. are automatically verified. The function fails with JWTError::InvalidAuthenticationTag if the authentication tag is invalid for the given key.
The full set of claims can be inspected in the claims object if necessary. NoCustomClaims means that only the standard set of claims is used by the application, but application-defined claims can also be supported.
Extra verification steps can optionally be enabled via the ValidationOptions structure:
```rust let mut options = VerificationOptions::default(); // Accept tokens that will only be valid in the future options.acceptfuture = true; // accept tokens even if they have expired up to 15 minutes after the deadline options.timetolerance = Some(Duration::frommins(15)); // reject tokens if they were issued more than 1 hour ago options.maxvalidity = Some(Duration::fromhours(1)); // reject tokens if they don't come from a specific issuer options.requiredissuer = Some("example app".to_string()); // see the documentation for the full list of available options
let claims = key.verify_token::
RS*, PS*, ES* and EdDSA algorithms) exampleA signature requires a key pair: a secret key used to create tokens, and a public key, that can only verify them.
Always use a signature scheme if both parties do not ultimately trust each other, such as tokens exchanged between clients and API providers.
Key creation:
```rust use jwt_simple::prelude::*;
// create a new key pair for the ES256 JWT algorithm
let key_pair = ES256KeyPair::generate();
// a public key can be extracted from a key pair: let publickey = keypair.public_key(); ```
Keys can be exported as bytes for later reuse, and imported from bytes or, for RSA, from individual parameters, DER-encoded data or PEM-encoded data.
RSA key pair creation, using OpenSSL and PEM importation of the secret key:
sh
openssl genrsa -out private.pem 2048
openssl rsa -in private.pem -outform PEM -pubout -out public.pem
rust
let key_pair = RS384KeyPair::from_pem(private_pem_file_content)?;
let public_key = RS384PublicKey::from_pem(public_pem_file_content)?;
Token creation and verification work the same way as with HS* algorithms, except that tokens are created with a key pair, and verified using the corresponding public key.
Token creation:
rust
/// create claims valid for 2 hours
let claims = Claims::create(Duration::from_hours(2));
let token = key_pair.sign(claims)?;
Token verification:
rust
let claims = public_key.verify_token::<NoCustomClaims>(&token, None)?;
Available verification options are identical to the ones used with symmetric algorithms.
Claim objects support all the standard claims by default, and they can be set directly or via convenient helpers:
rust
let claims = Claims::create(Duration::from_hours(2)).
with_issuer("Example issuer").with_subject("Example subject");
But application-defined claims can also be defined. These simply have to be present in a serializable type (this requires the serde crate):
```rust
struct MyAdditionalData { userisadmin: bool, usercountry: String, } let myadditionaldata = MyAdditionalData { userisadmin: false, usercountry: "FR".to_string(), }; ```
Claim creation with custom data:
rust
let claims = Claims::with_custom_claims(my_additional_data, Duration::from_secs(30));
Claim verification with custom data. Note the presence of the custom data type:
rust
let claims = public_key.verify_token::<MyAdditionalData>(&token, None)?;
let user_is_admin = claims.custom.user_is_admin;
Properties such as the key identifier can be useful prior to tag or signature verification in order to pick the right key out of a set.
rust
let metadata = Token::decode_metadata(&token)?;
let key_id = metadata.key_id();
let algorithm = metadata.algorithm();
// all other standard properties are also accessible
IMPORTANT: neither the key ID nor the algorithm can be trusted. This is an unfixable design flaw of the JWT standard.
As a result, algorithm should be used only for debugging purposes, and never to select a key type.
Similarly, key_id should be used only to select a key in a set of keys made for the same algorithm.
At the bare minimum, verification using HS* must be prohibited if a signature scheme was originally used to create the token.
Key identifiers indicate to verifiers what public key (or shared key) should be used for verification. They can be attached at any time to existing shared keys, key pairs and public keys:
rust
let public_key_with_id = public_key.with_key_id(&"unique key identifier");
Instead of delegating this to applications, jwt-simple can also create such an identifier for an existing key:
rust
let key_id = public_key.create_key_id();
This creates an text-encoded identifier for the key, attaches it, and returns it.
If an identifier has been attached to a shared key or a key pair, tokens created with them will include it.
jwt-simple includes mechanisms to mitigate replay attacks:
create_nonce() claim function. The verification procedure can later reject any token that doesn't include the expected nonce (required_nonce verification option).This crate is not an endorsement of JWT. JWT is an awful design, and one of the many examples that "but this is a standard" doesn't necessarily mean that it is good.
I would highly recommend PASETO instead if you control both token creation and verification.
However, JWT is still widely used in the industry, and remains absolutely mandatory to communicate with popular APIs.
This crate was designed to:
None signature method for obvious reasons).