Built in support for JWTs

[jhannes]

Json Web Tokens are useful for Open ID Connect scenarios. Jsonbuddy could support these as built a built in features. Code example:

KeyPairGenerator keyGen = KeyPairGenerator.getInstance("RSA");
keyGen.initialize(256); // ???
KeyPair keyPair = keyGen.generateKeyPair();
PrivateKey privateKey = keyPair.getPrivate();

JwtTokenBuilder builder = new JwtTokenBuilder()
    .addAlgorithm("RS256")
    .addKid("keyId")
    .addClaim("iss", "some issuer")
    .addClaim("sub", "some subject");

JwtToken token = new JwtToken(builder.getHeader(), builder.getPayload(), builder.sign(privateKey));

createCertificateFromPublicKey(keyPair.getPublic());
assertThat(token.iss()).isEqualTo("some issuer");
assertThat(token.safeVerifySignature()).isTrue();

JwtToken token = new JwtToken(builder.getHeader(), builder.getPayload(), builder.sign(otherPrivateKey));
assertThat(token.safeVerifySignature()).isFalse();