jsonwebtoken

API documentation on docs.rs

Installation

Add the following to Cargo.toml:

jsonwebtoken = "7"
serde_derive = "1"
serde = "1"

How to use

Complete examples are available in the examples directory: a basic one and one with a custom header.

In terms of imports and structs:

extern crate jsonwebtoken as jwt;
#[macro_use]
extern crate serde_derive;

use jwt::{encode, decode, Header, Algorithm, Validation};

/// Our claims struct, it needs to derive `Serialize` and/or `Deserialize`
#[derive(Debug, Serialize, Deserialize)]
struct Claims {
    sub: String,
    company: String,
    exp: usize,
}

Encoding

The default algorithm is HS256.

let token = encode(&Header::default(), &my_claims, "secret".as_ref())?;

Custom headers & changing algorithm

All the parameters from the RFC are supported but the default header only has typ and alg set. If you want to set the kid parameter or change the algorithm for example:

let mut header = Header::default();
header.kid = Some("blabla".to_owned());
header.alg = Algorithm::HS512;
let token = encode(&header, &my_claims, "secret".as_ref())?;

Look at examples/custom_header.rs for a full working example.

Decoding

let token = decode::<Claims>(&token, "secret".as_ref(), &Validation::default())?;
// token is a struct with 2 params: header and claims

decode can error for a variety of reasons:

• the token or its signature is invalid
• error while decoding base64 or the result of decoding base64 is not valid UTF-8
• validation of at least one reserved claim failed

In some cases, for example if you don't know the algorithm used, you will want to only decode the header:

let header = decode_header(&token)?;

This does not perform any validation on the token.

Validation

This library validates automatically the exp claim. nbf is also validated if present. You can also validate the sub, iss and aud but those require setting the expected value in the Validation struct.

Since validating time fields is always a bit tricky due to clock skew, you can add some leeway to the iat, exp and nbf validation by setting a leeway parameter.

Last but not least, you will need to set the algorithm(s) allowed for this token if you are not using HS256.

use jsonwebtoken::{Validation, Algorithm};

// Default validation: the only algo allowed is HS256
let validation = Validation::default();
// Quick way to setup a validation where only the algorithm changes
let validation = Validation::new(Algorithm::HS512);
// Adding some leeway (in seconds) for exp and nbf checks
let mut validation = Validation {leeway: 60, ..Default::default()};
// Checking issuer
let mut validation = Validation {iss: Some("issuer".to_string()), ..Default::default()};
// Setting audience
let mut validation = Validation::default();
validation.set_audience(&"Me"); // string
validation.set_audience(&["Me", "You"]); // array of strings

Algorithms

This library currently supports the following:

• HS256
• HS384
• HS512
• RS256
• RS384
• RS512
• PS256
• PS384
• PS512
• ES256
• ES384

RSA

jsonwebtoken can read DER and PEM encoded keys.

DER Encoded

If you have openssl installed, you can run the following commands to obtain the DER keys from PKCS#1 (ie with BEGIN RSA PUBLIC KEY) .pem. If you have a PKCS#8 pem file (ie starting with BEGIN PUBLIC KEY), you will need to first convert it to PKCS#1: openssl rsa -pubin -in <filename> -RSAPublicKey_out -out <filename>.

// private key
$ openssl rsa -in private_rsa_key.pem -outform DER -out private_rsa_key.der
// public key
$ openssl rsa -in private_rsa_key.der -inform DER -RSAPublicKey_out -outform DER -out public_key.der

If you are getting an error with your public key, make sure you get it by using the command above to ensure it is in the right format.

PEM Encoded

To generate a PKCS#1 RSA key, run openssl genrsa -out private_rsa_key_pkcs1.pem 2048 To convert a PKCS#1 RSA key to a PKCS#8 RSA key, run openssl pkcs8 -topk8 -inform pem -in private_rsa_key_pkcs1.pem -outform pem -nocrypt -out private_rsa_key_pkcs8.pem

To use a PEM encoded private / public keys, a pem struct is returned by decode_pem. This carries the lifetime of the data inside. Finally to use the key like any other use the .as_key(alg) function on the pem struct.

let privkey_pem = decode_pem(pem_string_here).unwrap();
let privkey = privkey_pem.as_key(Algorithm::RS256).unwrap();

ECDSA

jsonwebtoken can read PKCS#8 DER encoded private keys and public keys, as well as PEM encoded keys. Like RSA, to read a PEM key, you must use the pem decoder.

To generate an EC key, you can do the following.

// private key
openssl ecparam -genkey -name prime256v1 | openssl ec -out private_key.pem
// public key
openssl ec -in private_key.pem -pubout -out public_key.pem