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JWT (v3.4)

pac4j allows you to validate JSON Web Token.

The JWT support is based on the excellent Nimbus JOSE JWT library and you should consider reading this algorithm selection guide.

1) Dependency

You need to use the following module: pac4j-jwt.

Example (Maven dependency):

<dependency>
    <groupId>org.pac4j</groupId>
    <artifactId>pac4j-jwt</artifactId>
    <version>${pac4j.version}</version>
</dependency>

2) JwtAuthenticator

The JwtAuthenticator validates JWT tokens produced by the JwtGenerator or by other systems.

It can be defined for HTTP clients which deal with TokenCredentials.

It supports plain text, signed and/or encrypted JWT tokens. In all cases, the JwtAuthenticator requires the JWT to have a subject (sub claim) unless it will throw an exception. If the provided JWT has an expiration date, then JwtAuthenticator may also be configured to only accept JWTs that pass a date criteria that is compared against the JWT expiration date, via JwtAuthenticator#setExpirationTime()

Notice that for security reasons, plain text JWT tokens will be accepted ONLY if no signature configuration is defined. If one or more signature configurations are defined, the JWT tokens are expected to be signed accordingly.

▸ Signature

To handle signed JWT, you must define one or more SignatureConfiguration with the addSignatureConfiguration method.

Three signature configurations are available: with a secret (SecretSignatureConfiguration), using an RSA key pair (RSASignatureConfiguration) or using an elliptic-curve key pair (ECSignatureConfiguration).

To verify a signed JWT, the defined signature configurations will be tried successfully (if the algorithm of the JWT matches the one supported by the signature configuration).

▸ Encryption

To handle encrypted JWT, you must define one or more EncryptionConfiguration with the addEncryptionConfiguration method.

Like for signature configurations, three encryption configurations are available: with a secret (SecretEncryptionConfiguration), using an RSA key pair (RSAEncryptionConfiguration) or using an elliptic-curve key pair (ECEncryptionConfiguration).

To decrypt an encrypted JWT, the defined encryption configurations will be tried successfully (if the algorithm of the JWT matches the one supported by the encryption configuration).

Example:

JwtAuthenticator jwtAuthenticator = new JwtAuthenticator();

# define two signature configurations (one based on the KEY2 secret and the other one based on a generated RSA key pair)
jwtAuthenticator.addSignatureConfiguration(new SecretSignatureConfiguration(KEY2));
KeyPairGenerator keyGen = KeyPairGenerator.getInstance("RSA");
KeyPair rsaKeyPair = keyGen.generateKeyPair();
jwtAuthenticator.addSignatureConfiguration(new RSASignatureConfiguration(rsaKeyPair));

# define two encryption configurations (one based on the SECRET secret and the other one based on a generated elliptic curve key pair)
jwtAuthenticator.addEncryptionConfiguration(new SecretEncryptionConfiguration(SECRET));
KeyPairGenerator keyGen = KeyPairGenerator.getInstance("EC");
KeyPair ecKeyPair = keyGen.generateKeyPair();
ECEncryptionConfiguration encConfig = new ECEncryptionConfiguration(ecKeyPair);
encConfig.setAlgorithm(JWEAlgorithm.ECDH_ES_A128KW);
encConfig.setMethod(EncryptionMethod.A192CBC_HS384);
jwtAuthenticator.addEncryptionConfiguration(encConfig);

jwtAuthenticator.validate(new TokenCredentials(token, "myclient"));

The JwtAuthenticator also offers two convenient methods to handle JWT:

▸ User profiles

3) JwtGenerator

To generate a plain text, signed and/or encrypted JWT, a JwtGenerator can be defined with a SignatureConfiguration or/and EncryptionConfiguration.

Example:

JwtGenerator<FacebookProfile> generator = new JwtGenerator<>(new SecretSignatureConfiguration(SECRET), new SecretEncryptionConfiguration(SECRET));
String token = generator.generate(facebookProfile);

JWTs may also be generated with an assigned expiration time:

generator.setExpirationTime(new Date());

4) JWK

If your configuration is available as a JSON JWK, you can use the methods of the JWKHelper to:

Then, you’ll be able to build the appropriate signature or encryption configuration.