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JWTs for Java

This is not an officially supported Google product

CircleCI Coverage Status License

A Java implementation of JSON Web Tokens (draft-ietf-oauth-json-web-token-08).

If you're looking for an Android version of the JWT Decoder take a look at our JWTDecode.Android library.

Installation

Maven

<dependency>
    <groupId>com.auth0</groupId>
    <artifactId>java-jwt</artifactId>
    <version>3.3.0</version>
</dependency>

Gradle

compile 'com.auth0:java-jwt:3.3.0'

Available Algorithms

The library implements JWT Verification and Signing using the following algorithms:

JWS Algorithm Description
HS256 HMAC256 HMAC with SHA-256
HS384 HMAC384 HMAC with SHA-384
HS512 HMAC512 HMAC with SHA-512
RS256 RSA256 RSASSA-PKCS1-v1_5 with SHA-256
RS384 RSA384 RSASSA-PKCS1-v1_5 with SHA-384
RS512 RSA512 RSASSA-PKCS1-v1_5 with SHA-512
ES256 ECDSA256 ECDSA with curve P-256 and SHA-256
ES384 ECDSA384 ECDSA with curve P-384 and SHA-384
ES512 ECDSA512 ECDSA with curve P-521 and SHA-512

Supported token profile types

Basic Token

  • Standard claims: iss, sub, iat, jti
  • Nonstandard claims: aud, exp, nbf

Extended Token

  • Standard claims: name, email, picture, iss, sub, iat
  • Nonstandard claims: aud, exp, nbf

Access Token

  • Standard claims: iss, sub, iat
  • Nonstandard claims: aud, exp

Facebook Token

  • Standard claims: user_id, app_id, issued_at
  • Nonstandard claims: expired_at

Google Token

  • Standard claims: name, email, picture, iss, sub, iat
  • Nonstandard claims: exp, aud

Implicit Access Token

  • Standard claims: iss, sub, iat
  • Nonstandard claims: aud

Refresh Token

  • Standard claims: refresh_token, access_token

Risc Token

  • Standard claims: jti, iss, sub, iat
  • Nonstandard claims: aud, nbf, exp

Scoped Access Token

  • Standard claims: iss, sub, iat, scope
  • Nonstandard claims: aud, exp

Pick the Algorithm

The Algorithm defines how a token is signed and verified. It can be instantiated with the raw value of the secret in the case of HMAC algorithms, or the key pairs or KeyProvider in the case of RSA and ECDSA algorithms. Once created, the instance is reusable for token signing and verification operations.

When using RSA or ECDSA algorithms and you just need to sign JWTs you can avoid specifying a Public Key by passing a null value. The same can be done with the Private Key when you just need to verify JWTs.

Using static secrets or keys:

//HMAC
Algorithm algorithmHS = Algorithm.HMAC256("secret");

//RSA
RSAPublicKey publicKey = //Get the key instance
RSAPrivateKey privateKey = //Get the key instance
Algorithm algorithmRS = Algorithm.RSA256(publicKey, privateKey);

Using a KeyProvider:

By using a KeyProvider you can change in runtime the key used either to verify the token signature or to sign a new token for RSA or ECDSA algorithms. This is achieved by implementing either RSAKeyProvider or ECDSAKeyProvider methods:

  • getPublicKeyById(String kid): Its called during token signature verification and it should return the key used to verify the token. If key rotation is being used, e.g. JWK it can fetch the correct rotation key using the id. (Or just return the same key all the time).
  • getPrivateKey(): Its called during token signing and it should return the key that will be used to sign the JWT.
  • getPrivateKeyId(): Its called during token signing and it should return the id of the key that identifies the one returned by getPrivateKey(). This value is preferred over the one set in the JWTCreator.Builder#withKeyId(String) method. If you don't need to set a kid value avoid instantiating an Algorithm using a KeyProvider.

The following snippet uses example classes showing how this would work:

final JwkStore jwkStore = new JwkStore("{JWKS_FILE_HOST}");
final RSAPrivateKey privateKey = //Get the key instance
final String privateKeyId = //Create an Id for the above key

RSAKeyProvider keyProvider = new RSAKeyProvider() {
    @Override
    public RSAPublicKey getPublicKeyById(String kid) {
        //Received 'kid' value might be null if it wasn't defined in the Token's header
        RSAPublicKey publicKey = jwkStore.get(kid);
        return (RSAPublicKey) publicKey;
    }

    @Override
    public RSAPrivateKey getPrivateKey() {
        return privateKey;
    }

    @Override
    public String getPrivateKeyId() {
        return privateKeyId;
    }
};

Algorithm algorithm = Algorithm.RSA256(keyProvider);
//Use the Algorithm to create and verify JWTs.

For simple key rotation using JWKs try the jwks-rsa-java library.

Create and Sign a Token

You'll first need to create a JWTCreator instance by calling JWT.create(). Use the builder to define the custom Claims your token needs to have. Finally to get the String token call sign() and pass the Algorithm instance.

  • Example using HS256
try {
    Algorithm algorithm = Algorithm.HMAC256("secret");
    String token = JWT.create()
        .withIssuer("auth0")
        .sign(algorithm);
} catch (UnsupportedEncodingException exception){
    //UTF-8 encoding not supported
} catch (JWTCreationException exception){
    //Invalid Signing configuration / Couldn't convert Claims.
}
  • Example using RS256
RSAPublicKey publicKey = //Get the key instance
RSAPrivateKey privateKey = //Get the key instance
try {
    Algorithm algorithm = Algorithm.RSA256(publicKey, privateKey);
    String token = JWT.create()
        .withIssuer("auth0")
        .sign(algorithm);
} catch (JWTCreationException exception){
    //Invalid Signing configuration / Couldn't convert Claims.
}

If a Claim couldn't be converted to JSON or the Key used in the signing process was invalid a JWTCreationException will raise.

NOTE: Each token has a NoneAlgorithm boolean value which is set to False by default unless set explicitly.

GoogleJwtCreator.build().setIsNoneAlgorithmAllowed(true)

If the none algorithm property is set to true as done above, the following error will be thrown when algorithm 'none' is used: "None algorithm isn't allowed".

Serializing a token

When signing, you can encode via a 16-byte, 32-byte, the standard 64-byte, and a JSON encoding. When you call the method standard sign() as in the example above, the token is 64-byte encoded. To encode via a 16-byte, call signBase16Encoding(), via a 32-byte, call signBase32Encoding(), and via a JSON encoding, call signJSONEncoding().

Verify a Token

You'll first need to create a Verification instance by calling JWT.require() and passing the Algorithm instance. Once you have the Verification instance, you can call the corresponding verifier method. For the example of Google, you would have a GoogleVerificiation instance that has inherited from the Verification instance in order to call createVerifierForGoogle(), and you would pass in the claims that you would want to be verified. Once you call build, you would get back a JWT object and with that, you would call decode() while passing in the token that was created after signing. You will get back a DecodedJWT object, which contains all of the claims, and you can verify those claims against what's the expected claims by calling verifyClaims().

  • Example using HS256
String token = "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXUyJ9.eyJpc3MiOiJhdXRoMCJ9.AbIJTDMFc7yUa5MhvcP03nJPyCPzZtQcGEp-zWfOkEE";
Algorithm algorithm = Algorithm.HMAC256("secret");
GoogleVerification verification = GoogleJWT.require(algorithm);
JWT verifier = verification.createVerifierForGoogle(PICTURE, EMAIL, asList("accounts.fake.com"), asList("audience"),
       NAME, 1, 1).build();
DecodedJWT jwt = verifier.decode(token);
Map<String, Claim> claims = jwt.getClaims();
verifyClaims(claims, exp);
  • Example using RS256
String token = "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXUyJ9.eyJpc3MiOiJhdXRoMCJ9.AbIJTDMFc7yUa5MhvcP03nJPyCPzZtQcGEp-zWfOkEE";
RSAPublicKey publicKey = //Get the key instance
RSAPrivateKey privateKey = //Get the key instance

Algorithm algorithm = Algorithm.RSA256(publicKey, privateKey);
GoogleVerification verification = GoogleJWT.require(algorithm);
JWT verifier = verification.createVerifierForGoogle(PICTURE, EMAIL, asList("accounts.fake.com"), asList("audience"),
    NAME, 1, 1).build();
DecodedJWT jwt = verifier.decode(token);
Map<String, Claim> claims = jwt.getClaims();
verifyClaims(claims, exp);

If the token has a Claim requirement that has not been met, an InvalidClaimException will raise. If the token has an invalid signature, an AlgorithmMismatchException will raise.

Deserializing a token

In order to recover the DecodedJWT after signing, you need to decode with the appropriate decode method corresponding to the appropriate encode method. For the standard 64-byte encoding, to recover the DecodedJWT, you call decode() as in the example above. When you encode via 16-bytes, you call decode16Bytes(), via 32-bytes, call decode32Bytes(), and via a JSON encoding, call decodeJSON().

Time Validation

The JWT token may include DateNumber fields that can be used to validate that:

  • The token was issued in a past date "iat" < TODAY
  • The token hasn't expired yet "exp" > TODAY and
  • The token can already be used. "nbf" > TODAY

When verifying a token the time validation occurs automatically, resulting in a JWTVerificationException being throw when the values are invalid. If any of the previous fields are missing they won't be considered in this validation.

To specify a nbf value in which the Token should still be considered valid, use the withNbf() method in the respective Creator builder and pass a Date object. This applies to every item listed above. NOTE: Nbf and iat date values should be in the past, but the exp value should be in the future.

Verification verifier = JWT.require(algorithm)
    .withNbf(new Date(2016,1,1))
    .build();

You can also specify a custom value for a given Date claim and override the default one for only that claim.

Verification verifier = JWT.require(algorithm)
    .withNbf(new Date(2016,1,1))
    .withExp(new Date(2100,1,1))
    .build();

If you need to test this behaviour in your lib/app cast the Verification instance to a BaseVerification to gain visibility of the verification.build() method that accepts a custom Clock. e.g.:

BaseVerification verification = (BaseVerification) JWT.require(algorithm)
    .acceptLeeway(1)
    .acceptExpiresAt(5);
Clock clock = new CustomClock(); //Must implement Clock interface
JWT verifier = verification.build(clock);

Decode a Token

This example is for an Implicit JWT token and can be applied to all the types of tokens:

String token = "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOlsic3ViamVjdCJdLCJpc3MiOlsiYWNjb3VudHMuZmFrZS5jb20iXSwiYXVkIjoiYXVkaWVuY2UiLCJpYXQiOi0xMjQ1MjgxNTI3fQ.-eRoMolUy7PnEcpvfs-jTEvP6qagBZ1G_lqp1jY3Nqg";
Verification verification = ImplicitJWT.require(algorithm);
JWT verifier = verification.createVerifierForImplicit(asList("accounts.fake.com"), asList("audience"), 1).build();
DecodedJWT jwt = verifier.decode(token);

If the token has an invalid syntax or the header or payload are not JSONs, a JWTDecodeException will raise.

Header Claims

Algorithm ("alg")

Returns the Algorithm value or null if it's not defined in the Header.

String algorithm = jwt.getAlgorithm();

Type ("typ")

Returns the Type value or null if it's not defined in the Header.

String type = jwt.getType();

Content Type ("cty")

Returns the Content Type value or null if it's not defined in the Header.

String contentType = jwt.getContentType();

Key Id ("kid")

Returns the Key Id value or null if it's not defined in the Header.

String keyId = jwt.getKeyId();

Private Claims

Additional Claims defined in the token's Header can be obtained by calling getHeaderClaim() and passing the Claim name. A Claim will always be returned, even if it can't be found. You can check if a Claim's value is null by calling claim.isNull().

Claim claim = jwt.getHeaderClaim("owner");

When creating a Token with the JWTCreator.init() you can specify header Claims by calling withHeader() and passing both the map of claims.

Map<String, Object> headerClaims = new HashMap();
headerClaims.put("owner", "auth0");
String token = JWTCreator.init()
        .withHeader(headerClaims)
        .sign(algorithm);

The alg and typ values will always be included in the Header after the signing process.

Payload Claims

Issuer ("iss")

Returns the Issuer value or null if it's not defined in the Payload.

String issuer = jwt.getIssuer();

Subject ("sub")

Returns the Subject value or null if it's not defined in the Payload.

String subject = jwt.getSubject();

Audience ("aud")

Returns the Audience value or null if it's not defined in the Payload.

List<String> audience = jwt.getAudience();

Expiration Time ("exp")

Returns the Expiration Time value or null if it's not defined in the Payload.

Date expiresAt = jwt.getExpiresAt();

Not Before ("nbf")

Returns the Not Before value or null if it's not defined in the Payload.

Date notBefore = jwt.getNotBefore();

Issued At ("iat")

Returns the Issued At value or null if it's not defined in the Payload.

Date issuedAt = jwt.getIssuedAt();

JWT ID ("jti")

Returns the JWT ID value or null if it's not defined in the Payload.

String id = jwt.getId();

Nonstandard Claims

Nonstandard Claims defined in the token's Payload can be obtained by calling getClaims() or getClaim() and passing the Claim name. A Claim will always be returned, even if it can't be found. You can check if a Claim's value is null by calling claim.isNull().

Map<String, Claim> claims = jwt.getClaims();    //Key is the Claim name
Claim claim = claims.get("isAdmin");

or

Claim claim = jwt.getClaim("isAdmin");

When creating an Implicit Token for example with the ImplicitJwtCreator.build() you can specify a custom Claim by calling withNonStandardClaim() and passing both the name and the value.

String token = ImplicitJwtCreator.build()
        .withNonStandardClaim("nonStandardClaim", 123)
        .withArrayClaim("array", new Integer[]{1, 2, 3})
        .sign(algorithm);

NOTE: Nonstandard claims aside from aud, exp, and nbf do not need to verified.

Currently supported classes for custom JWT Claim creation and verification are: Boolean, Integer, Double, String, Date and Arrays of type String and Integer.

Claim Class

The Claim class is a wrapper for the Claim values. It allows you to get the Claim as different class types. The available helpers are:

Primitives

  • asBoolean(): Returns the Boolean value or null if it can't be converted.
  • asInt(): Returns the Integer value or null if it can't be converted.
  • asDouble(): Returns the Double value or null if it can't be converted.
  • asLong(): Returns the Long value or null if it can't be converted.
  • asString(): Returns the String value or null if it can't be converted.
  • asDate(): Returns the Date value or null if it can't be converted. This must be a NumericDate (Unix Epoch/Timestamp). Note that the JWT Standard specified that all the NumericDate values must be in seconds.

Custom Classes and Collections

To obtain a Claim as a Collection you'll need to provide the Class Type of the contents to convert from.

  • as(class): Returns the value parsed as Class Type. For collections you should use the asArray and asList methods.
  • asMap(): Returns the value parsed as Map<String, Object>.
  • asArray(class): Returns the value parsed as an Array of elements of type Class Type, or null if the value isn't a JSON Array.
  • asList(class): Returns the value parsed as a List of elements of type Class Type, or null if the value isn't a JSON Array.

If the values can't be converted to the given Class Type a JWTDecodeException will raise.

Issue Reporting

If you have found a bug or if you have a feature request, please report them at this repository issues section. Please do not report security vulnerabilities on the public GitHub issue tracker.

Authors

Auth0 LLC, Google LLC

License

This project is licensed under the MIT license. See the LICENSE file for more info.