Introduction

JOSE is a set of high quality specifications that specify how data payloads can be signed/validated and/or encrypted/decrypted with the cryptographic properties set in the JSON-formatted metadata (headers). The data to be secured can be in JSON or other format (plain text, XML, binary data).

JOSE is a key piece of the advanced OAuth2-based applications such as OpenIdConnect but can also be successfully used for securing the regular HTTP web service communications.

CXF 3.1.x and 3.2.0 provides a complete implementation of JOSE.

Maven Dependencies

Having the following dependency will let the developers write JOSE code: creating and securing JSON Web Tokens (JWT), and securing the arbitrary data (not only JSON)

<dependency>
  <groupId>org.apache.cxf</groupId>
  <artifactId>cxf-rt-rs-security-jose</artifactId>
  <version>3.1.7</version>
</dependency>

Having the following dependency will let the developers use JAX-RS JOSE filters which will transparently sign and/or encrypt the data streams, and decrypt or/and validate the incoming JOSE sequences and make the original data available for the processing.

<dependency>
  <groupId>org.apache.cxf</groupId>
  <artifactId>cxf-rt-rs-security-jose-jaxrs</artifactId>
  <version>3.1.7</version>
</dependency>

You may also need to include Bouncy Castle:

<dependency>
     <groupId>org.bouncycastle</groupId>
     <artifactId>bcprov-ext-jdk15on</artifactId>
     <version>1.54</version>
</dependency>

BouncyCastle provider can be registered and unregistered as follows:

import java.security.Security;
import org.bouncycastle.jce.provider.BouncyCastleProvider;

private static void registerBouncyCastle() throws Exception {
    Security.addProvider(new BouncyCastleProvider());    
}

private static void unregisterBouncyCastle() throws Exception {
    Security.removeProvider(BouncyCastleProvider.PROVIDER_NAME);    
}

Java and JCE Policy 

Java7 or higher is recommended for most cases: Java6 does not support JWE AES-GCM at all while with BouncyCastle it is not possible to submit JWE Header properties as an extra input to the encryption process to get them integrity protected which is not JWE compliant.

Unlimited JCE Policy for Java 7/8/9 needs to be installed if a size of the encrypting key is 256 bits (example, JWE A256GCM).

JOSE Overview and Implementation

JOSE consists of the following key parts:

• JWA - JSON Web Algorithms where all supported signature and encryption algorithms are listed
• JWK - JSON Web Keys - introduces a JSON format for describing the public and private keys used by JWA algorithms
• JWS - JSON Web Signature - describes how the data can be signed or validated and introduces compact and JSON JWS formats for representing the signed data
• JWE - JSON Web Encryption - describes how the data can be encrypted or decrypted and introduces compact and JSON JWE formats for representing the encrypted data  

Additionally, JWT (JSON Web Token), while technically being not part of JOSE, is often used as an input material to JWS and JWE processors, especially in OAuth2 flows (example: OAuth2 access tokens can be represented internally as JWT, OpenIdConnect IdToken and UserInfo are effectively JWTs). JWT describes how a set of claims in JSON format can be either JWS-signed and/or JWE-enctypted. 

JWA Algorithms

All JOSE signature and encryption algorithms are grouped and described in the JWA (JSON Web Algorithms) specification.

The algorithms are split into 3 categories: signature algorithms (HMAC, RSA, Elliptic Curve), algorithms for supporting the encryption of content encryption keys (RSA-OAEP, AES Key Wrap, etc), and algorithms for encrypting the actual content (AES GCM, etc).

All JWS and JWE algorithms process not only the actual data but also the meta-data (the algorithm properties) thus ensuring the algorithm properties are integrity-protected, additionally JWE algorithms produce authentication tags which ensure the already encrypted content won't be manipulated.

Please refer to the specification to get all the information needed (with the follow up links to the corresponding RFC when applicable) about a particular signature or encryption algorithm: the properties, recommended key sizes, other security considerations related to all of or some specific algorithms. CXF JOSE code already enforces a number of the recommended constraints.

CXF offers the utility support for working with JWA algorithms in this package.

Typically one would supply an algorithm property in a type-safe way either to JWS or JWE processor, for example,  SignatureAlgorithm.HS256 for JWS, KeyAlgorithm.A256KW plus ContentAlgorithm.A256GCM for JWE, etc. Each enum has methods for checking a key size, JWA and Java JCA algorithm names.

JWK Keys

JWK (JSON Web Key) is a JSON document describing the cryptographic key properties. JWKs are very flexible and one can expect JWKs becoming one of the major mechanisms for representing and storing cryptographic keys. While one does not have to represent the keys as JWK in order to sign or encrypt the document and rely on Java JCA secret and asymmetric keys instead, JWK is a preferred representation of signature or encryption keys in JOSE.

For example:

{
   "kty":"oct",
   "k":"AyM1SysPpbyDfgZld3umj1qzKObwVMkoqQ-EstJQLr_T-1qS0gZH75aKtMN3Yj0iPS4hcgUuTwjAzZr1Z9CAow",
   "kid":"Secret HMAC key"
}

or

{
  "kty":"RSA",
  "n": "0vx7agoebGcQSuuPiLJXZptN9nndrQmbXEps2aiAFbWhM78LhWx
     4cbbfAAtVT86zwu1RK7aPFFxuhDR1L6tSoc_BJECPebWKRXjBZCiFV4n3oknjhMs
     tn64tZ_2W-5JsGY4Hc5n9yBXArwl93lqt7_RN5w6Cf0h4QyQ5v-65YGjQR0_FDW2
     QvzqY368QQMicAtaSqzs8KJZgnYb9c7d0zgdAZHzu6qMQvRL5hajrn1n91CbOpbI
     SD08qNLyrdkt-bFTWhAI4vMQFh6WeZu0fM4lFd2NcRwr3XPksINHaQ-G_xBniIqb
     w0Ls1jF44-csFCur-kEgU8awapJzKnqDKgw",
  "e":"AQAB",
  "alg":"RS256",
  "kid":"Public RSA Key"}

A 'kid' property can be of special interest as it allows to identify a key but also help with the simple key rotation mechanism realized (ex, OIDC Asymmetric Key Rotation).

A collection of JWK keys is called a JWK Key Set which is represented as JSON array of JWKs.

CXF offers a utility support for reading and writing JWK keys and key sets and for working with the encrypted inlined and standalone JWK stores in this package.

For example, a key set containing public JWK keys can be seen here and referred to from the configuration properties. The private (test) key set can be represented in a clear form, though most likely you'd want a private key set encrypted and referred to like this. 

One can inline the encrypted key or the key set directly in the configuration properties. For example, here is how an encrypted single JWK key is inlined. Similarly, here is how an encrypted collection of keys is inlined.

CXF assumes that the JWK keys have been encrypted if a password provider is available in scope, it is typically registered with JAX-RS endpoints. The encryption is done with a password based PBES2 algorithm. 

Support for the pluggable strategies for loading JWKs is on the map.

For example, here is how you can load a JWK key using its 'kid':

InputStream is = JsonWebKeyTest.class.getResourceAsStream(fileName);
JsonWebKeys keySet = JwkUtils.readJwkSet(is);
JsonWebKey key = keySet.getKey("Public RSA Key");
String thumbprint = JwkUtils.getThumbprint(key);
assertEquals("NzbLsXh8uDCcd-6MNwXF4W_7noWXFZAfHkxZsRGC9Xs", thumbprint);
KeyType keyType = key.getKeyType();
assertEquals(KeyType.RSA, thumbprint);

JsonWebKeys also supports the retrieval of keys by their type (RSA, EC, Octet) and operation (ENCRYPT, SIGN, etc). 
Once you have JWK loaded it is typically submitted to JWS or JWE providers.

JWS Signature

JWS (JSON Web Signature) document describes how a document content can be signed. For example, Appendix A1 shows how the content can be signed with an HMAC key

CXF ships JWS related classes in this package and offers a support for all of JWA signature algorithms.

Signature and Verification Providers

JwsSignatureProvider supports signing the content, JwsSignatureVerifier - validating the signatures.

Note the signature and verification capabilities are represented by 2 different interfaces - it was done to keep the interfaces minimalistic and have the concerns separated which can be appreciated most in the cases where the code only signs or only validates.

The following table shows the algorithms and the corresponding providers (org.apache.cxf.rs.security.jose.jws package):

Either of these providers (except for None) can be initialized with the keys loaded from JWK or Java JKS stores or from the in-memory representations.

RS256/384/512 algorithms are likely to be used most often at the moment due to existing JKS stores being available everywhere and a relatively easy way of making the public validation keys available. 'None' algorithm might be useful when a JWS sequence is subsequently JWE-encrypted or when a 2-way TLS (with client and server certificates) is used.

Once you have decided which algorithm needs to be supported you can initialize an appropriate pair of JwsSignatureProvider and JwsSignatureVerifier if both signing the data and the verification are needed. If only the signing is needed - select JwsSignatureProvider, only the verification - select JwsSignatureVerifier. The selected providers are submitted to JWS Compact or JWS JSON producers or consumers.

JwsUtils utility class has a lot of helper methods to load JwsSignatureProvider or JwsSignatureVerifier and to get JWS sequences created and validated.

JWS Compact

JWS Compact representation is the most often used JWS sequence format. It is the concatenation of Base64URL-encoded sequence of JWS headers (algorithm and other properties),  Base64URL-encoded sequence of the actual data being protected and Base64URL-encoded sequence of the signature algorithm output bytes.

JwsCompactProducer and JwsCompactConsumer offer a support for producing and consuming compact JWS sequences, protecting the data in JSON or non-JSON formats.

JwsJwtCompactProducer and JwsJwtCompactConsumer are their simple extensions which help with processing typed JWT Tokens.

 For example, here is how an Appendix A1 example can be done in CXF:

JwtClaims claims = new JwtClaims();
claims.setIssuer("joe");
claims.setExpiryTime(1300819380L);
claims.setClaim("http://example.com/is_root", Boolean.TRUE);

JwsCompactProducer jwsProducer = new JwsJwtCompactProducer(claims);

// Sign
// Load HmacJwsSignatureProvider directly, see the next example for the alternative approach
String jwsSequence = jwsProducer.signWith(new HmacJwsSignatureProvider(ENCODED_MAC_KEY, SignatureAlgorithm.HS256));

// Validate
JwsJwtCompactConsumer jwsConsumer = new JwsJwtCompactConsumer(jwsSequence);

// Load HmacJwsSignatureVerifier directly, see the next example for the alternative approach
jwsConsumer.verifySignatureWith(new HmacJwsSignatureVerifier(ENCODED_MAC_KEY, SignatureAlgorithm.HS256)));

// Get the data
JwtClaims protectedClaims = jws.getJwtClaims();

In the above example, the data (JwtToken) is submitted to an instance of JwsCompactProducer (JwsJwtCompactProducer) and signed with an HMac key.

Here is another example:

JwsCompactProducer jwsProducer = new JwsCompactProducer("Hello World");

// Load private RSA key from the JWK Key set stored on the disk
InputStream is = JsonWebKeyTest.class.getResourceAsStream(fileName);
JsonWebKeys keySet = JwkUtils.readJwkSet(is);
JsonWebKey jwkPrivateRsaKey = keySet.getKey("Private RSA Key");

// Sign
String jwsSequence = jwsProducer.signWith(jwkPrivateRsaKey);

// Validate
JwsCompactConsumer jwsConsumer = new JwsCompactConsumer(jwsSequence);

// Load Public RSA Key from Java JKS Store
PublicKey publicRsaKey = CryptoUtils.loadPublicKey(keyStoreLocation, keyStorePassword, keyAlias, KeyStore.getDefaultType()); 

jws.verifySignatureWith(publicRsaKey);

// Get the data
String helloWorldString = jwsConsumer.getDecodedJwsPayload();

In this latest example a plain text sequence is encoded with a private RSA key loaded from the JWK store and validated with a public RSA key loaded from the existing Java JKS store.

JWS JSON

While JWS Compact is optimized and represents a concatenation of 3 Base64URL values, JWS JSON is an open JSON container, see Appendix 6.

The most interesting feature of JWS JSON is that allows a content be signed for multiple recipients. For example,  the immediate consumer will validate a signature with one key, forward the payload to the next consumer which will also validate the content with another key, etc.  

JwsJsonProducer and JwsJsonConsumer support producing and consuming JWS JSON sequences.

JwsJsonProducer producer = new JwsJsonProducer(UNSIGNED_PLAIN_JSON_DOCUMENT);
JwsHeaders headerEntries = new JwsHeaders(SignatureAlgorithm.HS256);
              
producer.signWith(new HmacJwsSignatureProvider(ENCODED_MAC_KEY_1, SignatureAlgorithm.HS256),
                  headerEntries);
producer.signWith(new HmacJwsSignatureProvider(ENCODED_MAC_KEY_2, SignatureAlgorithm.HS256),
                  headerEntries);
assertEquals(DUAL_SIGNED_JWS_JSON_DOCUMENT, producer.getJwsJsonSignedDocument());

JwsJsonConsumer consumer = new JwsJsonConsumer(DUAL_SIGNED_DOCUMENT); 

// Validate both signatures, see below how to validate and produce
JsonWebKeys jwks = readKeySet("jwkSet.txt");
        
List<JwsJsonSignatureEntry> sigEntries = consumer.getSignatureEntries();
assertEquals(2, sigEntries.size());

// 1st signature
String firstKid = (String)sigEntries.get(0).getKeyId();
JsonWebKey firstKey = jwks.getKey(firstKid);
assertTrue(sigEntries.get(0).verifySignatureWith(firstKey));
// 2nd signature
String secondKid = (String)sigEntries.get(1).getKeyId();
JsonWebKey secondKey = jwks.getKey(secondKid);
assertTrue(sigEntries.get(1).verifySignatureWith(secondKey));

// or if you wish to validate (ex with the firstKey loaded above) and forward it to the next consumer, do:
JwsSignatureProvider provider = JwsUtils.getSignatureProvider(firstKey);
String nextJwsJson = consumer.validateAndProduce(Collections.singletonList(provider));
// use WebClient to post nextJwsJson to the next consumer, with nextJwsJson being nearly identical to the original
// double-signed JWS JSON signature, minus the signature which was already validated, in this case nextJwsJson will 
// only have a single signature 

The above code produces a JWS JSON sequence containing two signatures, similarly to this example. If the sequence contains a single signature only then the JWS JSON 'signatures' array will contain a single 'signature' element, or the whole sequence can be flattened instead with the actual 'signatures' array dropped. JwsJsonProducer  does not produce the flattened sequence when only a single signature is used by default because 3rd party JWS JSON consumers may only be able to process the sequences with the 'signatures' array, so pass a 'supportFlattened' flag to JwsJsonProducer if needed. 

Does it make sense to use JWS JSON if you do not plan to do multiple signatures ? Indeed, if it is only a single signature then using JWS Compact is a good alternative, likely to be used most often.

However, even if you do a single signature, you may still want to try JWS JSON because is is easier to observe the individual JWS JSON structure parts when, example, checking the logs or TCP-tracing HTTP requests/responses. This is especially true when we start talking about an unencoded payload option, see below.

JWS with Detached Content

JWS with a Detached Content provides a way to integrity-protect some data without actually having these data included in the resulting JWS sequence.

For example, if the producer and consumer can both access the same shared piece of data, then the producer can sign these data, post the JWS sequence (without the data) to the consumer. The consumer will validate this JWS sequence and assert the data have not been modified by the time it has received and started validating the sequence. JWS Compact and JWS JSON Producer and Consumer provider constructors accept an optional 'detached' flag in cases were it is required.      

JWS with Unencoded Payload

By default, JWS Compact and JWS JSON sequences have the data first Base64Url encoded and then inlined in the resulting sequence. This is useful especially for JWS Compact which is used in OAuth2/OIDC  flows to represent the signed access or id tokens. 

One concern around the data being inlined is that it takes an extra time to Base64Url encode them which may become noticeable with large payloads, and another one is that one can not see the data while looking at JWS sequences in the logs or trace screens.

Thus a JWS with Unencoded Payload option (JWS header 'b64' property set to false) has been introduced to let users configure JWS Signature providers not to encode the actual data payload. As it happens it appears to be most useful when JWS JSON sequences are produced, see this example.

Note that JWS Compact also supports 'b64' property but only with the detached payloads. It is easier to appreciate the value of disabling Base64Url encoding with JWS JSON as seen in the example.

In CXF you can apply this option to both JWS Compact and JWS JSON sequences, here is a JWS JSON code fragment:

JwsJsonProducer producer = new JwsJsonProducer(UNSIGNED_PLAIN_JSON_DOCUMENT, true);
JwsHeaders headers = new JwsHeaders(SignatureAlgorithm.HS256);
headers.setPayloadEncodingStatus(false);
producer.signWith(new HmacJwsSignatureProvider(ENCODED_MAC_KEY_1, SignatureAlgorithm.HS256),
                  headers);

JWE Encryption

JWE (JSON Web Encryption) document describes how a document content, and, when applicable, a content encryption key, can be encrypted. For example, Appendix A1 shows how the content can be encrypted with a secret key using AesGcm with the actual content encryption key being encrypted using RSA-OAEP.

CXF ships JWE related classes in this package and offers a support for all of JWA key encryption and content encryption algorithms.

Key and Content Encryption Providers

JWE Encryption process typically involves a content-encryption key being generated with this key being subsequently encrypted/wrapped with a key known to the consumer. Thus CXF offers the providers for supporting the key-encryption algorithms and providers for supporting the content-encryption algorithms. Direct key encryption (where the content-encryption key is established out of band) is also supported.

KeyEncryptionProvider supports encrypting a content-encryption key, KeyDecryptionProvider - decrypting it.

The following table shows the key encryption algorithms and the corresponding providers (org.apache.cxf.rs.security.jose.jwe package):

RSA-OAEP algorithms are likely to be used most often at the moment due to existing JKS stores being available everywhere and a relatively easy way of making the public validation keys available.

ContentEncryptionProvider supports encrypting a generated content-encryption key, ContentDecryptionProvider - decrypting it.

The following table shows the content encryption algorithms and the corresponding providers:

All of the above providers can be initialized with the keys loaded from JWK or Java JKS stores or from the in-memory representations.

Once you have decided which key and content encryption algorithms need to be supported you can initialize JwsEncryptionProvider and JwsDecryptionProvider which do the actual JWE encryption/decryption work by coordinating with the key and content encryption providers. CXF ships JweEncryption (JwsEncryptionProvider) and JweDecryption (JweDecryptionProvider) helpers, simply pass them the preferred key and content encryption providers and have the content encrypted or decrypted.

JweEncryption and JweDecryption help with creating and processing JWE Compact sequences (see the next section).  JweEncryption can also help with streaming JWE JSON sequences (see JAX-RS JWE filters section).

Note that AesCbcHmacJweEncryption and AesCbcHmacJweDecryption providers supporting AES_CBC_HMAC_SHA2 contet encryption are extending JweEncryption and JweDecryption respectively. They implement the content encryption internally but do accept preferred key encryption/decryption providers.

Similarly, DirectKeyJweEncryption and DirectKeyJweDecryption are simple JweEncryption and JweDecryption extensions making it straighforward to do the direct key content encryption/decryption.

JweUtils utility class has a lot of helper methods to load key and and content encryption providers and get the data encrypted and decrypted.

JWE Compact

JWE Compact representation is the most often used JWE sequence format. It is the concatenation of 5 parts: Base64URL-encoded sequence of JWE headers (algorithm and other properties),  Base64URL-encoded sequence of JWE encryption key (empty in case of the direct encryption), Base64URL-encoded sequence of JWE Initialization vector, Base64URL-encoded sequence of the produced ciphertext (encrypted data) and finally Base64URL-encoded sequence of the authentication tag (integrity protection for the headers and the ciphertext itself).

JweCompactProducer and JweCompactConsumer offer a basic support for creating and consuming compact JWE sequences. In most cases you will likely prefer to use JweEncryption and JweDecryption instead: JweEncryption uses JweCompactProducer internally when its encrypt method is called (getEncryptedOutput will be discussed in the JAX-RS JWE filters section), and JweDecryption accepts only JWE Compact and uses JweCompactConsumer internally.

JweJwtCompactProducer and JwsJwtCompactConsumer help with directly encrypting typed JWT Tokens.

Here is the example of doing AES Key Wrap and AES CBC HMAC in CXF:

final String specPlainText = "Live long and prosper.";
        
AesWrapKeyEncryptionAlgorithm keyEncryption = new AesWrapKeyEncryptionAlgorithm(KEY_ENCRYPTION_KEY_A3, KeyAlgorithm.A128KW);
JweEncryptionProvider encryption = new AesCbcHmacJweEncryption(ContentAlgorithm.A128CBC_HS256,
                                                               keyEncryption);
String jweContent = encryption.encrypt(specPlainText.getBytes("UTF-8"), null);
        
AesWrapKeyDecryptionAlgorithm keyDecryption = new AesWrapKeyDecryptionAlgorithm(cekEncryptionKey);
JweDecryptionProvider decryption = new AesCbcHmacJweDecryption(keyDecryption);
String decryptedText = decryption.decrypt(jweContent).getContentText();
assertEquals(specPlainText, decryptedText);

Here is another example using RSA-OAEP key encryption and AES-GCM content encryption:

final String content = "Live long and prosper.";
// Load public RSA key from the JWK Key set stored on the disk
InputStream is = JsonWebKeyTest.class.getResourceAsStream(fileName);
JsonWebKeys keySet = JwkUtils.readJwkSet(is);
JsonWebKey jwkPublicRsaKey = keySet.getKey("Public RSA Key");
KeyEncryptionProvider keyEncryptionAlgo = JweUtils.getKeyEncryptionProvider(jwkPublicRsaKey); 
ContentEncryptionProvider contentEncryptionAlgo = JweUtils.getContentEncryptionProvider(ContentAlgorithm.A256GCM);
JweEncryptionProvider encryptor = new JweEncryption(keyEncryptionAlgo, contentEncryptionAlgo);

// or simply
// JweEncryptionProvider encryptor = JweUtils.createJweEncryptionProvider(jwkPublicRsaKey, ContentAlgorithm.A256GCM);

String jweOut = encryptor.encrypt(content.getBytes(StandardCharsets.UTF_8), null); 

// Load Private RSA Key from Java JKS Store
PrivateKey privateRsaKey = 
    CryptoUtils.loadPrivateKey(keyStoreLocation, keyStorePassword, privateKeyPassword, keyAlias, KeyStore.getDefaultType());

JweDecryptionProvider decryptor = JweUtils.createJweDecryptionProvider(jwkPrivateRsaKey, ContentAlgorithm.A256GCM);
String decryptedText = decryption.decrypt(jweContent).getContentText();
assertEquals(content, decryptedText);

JWE JSON

While JWE Compact is optimized and represents a concatenation of 5 Base64URL values, JWE JSON is an open JSON container, see Appendix A4.

The most interesting feature of JWE JSON is that allows a content be encrypted by multiple key encryption keys, with te resulting sequence targeted at multiple recipients. For example,  the immediate consumer will decrypt the content with its own key decryption key, forward the payload to the next consumer, etc.  

JweJsonProducer and JweJsonConsumer support producing and consuming JWS JSON sequences.

Here is the code example:

final String text = "The true sign of intelligence is not knowledge but imagination.";
SecretKey wrapperKey1 = CryptoUtils.createSecretKeySpec(WRAPPER_BYTES1, "AES");
SecretKey wrapperKey2 = CryptoUtils.createSecretKeySpec(WRAPPER_BYTES2, "AES");
        
JweHeaders protectedHeaders = new JweHeaders(ContentAlgorithm.A128GCM);
JweHeaders sharedUnprotectedHeaders = new JweHeaders();
sharedUnprotectedHeaders.setJsonWebKeysUrl("https://server.example.com/keys.jwks");
sharedUnprotectedHeaders.setKeyEncryptionAlgorithm(KeyAlgorithm.A128KW);
        
ContentEncryptionProvider contentEncryption = JweUtils.getContentEncryptionProvider(ContentAlgorithm.A128GCM);
        
KeyEncryptionProvider keyEncryption1 = JweUtils.getSecretKeyEncryptionAlgorithm(wrapperKey1, KeyAlgorithm.A128KW);
JweEncryptionProvider jweEnc1 = new JweEncryption(keyEncryption1, contentEncryption);

KeyEncryptionProvider keyEncryption2 = JweUtils.getSecretKeyEncryptionAlgorithm(wrapperKey2, KeyAlgorithm.A128KW);
JweEncryptionProvider jweEnc2 = new JweEncryption(keyEncryption2, contentEncryption);

List<JweEncryptionProvider> jweList = new LinkedList<JweEncryptionProvider>();
jweList.add(jweEnc1);
jweList.add(jweEnc2);
        
JweJsonProducer p = new JweJsonProducer(protectedHeaders,
                                        sharedUnprotectedHeaders,
                                        StringUtils.toBytesUTF8(text),
                                        StringUtils.toBytesUTF8(EXTRA_AAD_SOURCE),
                                        false);
String jweJsonOut = p.encryptWith(jweList);

// first consumer:
JweDecryptionProvider jweDecrypt = JweUtils.createJweDecryptionProvider(wrapperKey1, 
                                                                 KeyAlgorithm.A128KW, 
                                                                 ContentAlgorithm.A128GCM);
JweJsonConsumer c = new JweJsonConsumer(jweJsonOut);
// the consumer will iterate over JWE entries and will try to find the one which can be decrypted with this decryptor
// which is always precise if only a single receipient entry is available
// or do consumer.getRecipientsMap() returning a list of entries and their metadata to do a more precise selection.

String content = consumer.decryptWith(jweDecrypt).getContent();

If the sequence contains a single recipient entry only then the JWE JSON 'recipients' array will contain a single entry, or the whole sequence can be flattened instead with the actual 'recipients' array dropped. JweJsonProducer  does not produce the flattened sequence when only a single encryption is done by default because 3rd party JWE JSON consumers may only be able to process the sequences with the 'recipients' array, so pass a 'canBeFlat' flag to JwEJsonProducer if needed

Does it make sense to use JWE JSON if you do not plan to do multiple encryptions ? Most likely you will prefer JWE Compact if only a single recipient is targeted.

JSON Web Token

JWT (JSON Web Token) is a collection of claims in JSON format. It is simply a regular JSON document where each top elevel property is called a 'claim'.

JWT can be JWS signed and/or JWE encrypted like any other data structure.

JWT is mainly used in OAuth2 and OIDC applications to represent self-contained OAuth2 access tokens, OIDC IdToken, UserInfo, but can also be used in other contexts. For example, see the section below on linking JWT authentication tokens to JWS or JWE secured payloads.

CXF offers a JWT support in this package. Typically one would create a set of claims and submit them to JWS/JWE JWT processors, for example, see a JWS section above.

JWS and JWE Combined

If you have a requirement to sign the data and then encrypt the signed payload then it can be easily achieved by selecting a required JWS Producer and creating a JWS Compact sequence, and next submitting this sequence to a JWE producer, and processing it all in the reverse sequence

JOSE JAX-RS Filters

While working directly with JWS and JWE providers may be needed in the application code, JAX-RS users writing the code like this:

@Path("/bookstore")
public class BookStore {
    
    public BookStore() {
    }
    
    @POST
    @Path("/books")
    @Produces("text/plain")
    @Consumes("text/plain")
    public String echoText(String text) {
        return text;
    }
    
    @POST
    @Path("/books")
    @Produces("application/json")
    @Consumes("application/json")
    public Book echoBook(Book book) {
        return book;
    }
}

would expect JWS and/or JWE processing done before the resource method is invoked or after this method returned some response.

This is what CXF JOSE JAX-RS filters do, they help the client or server code get the application data JWS- or JWE-secured. The filters do it by loadng the configuration properties as described below in the Configuration section, and produce or consume JWS or JWE sequences.

Note, JWS Compact and JSON, as well as JWE Compact client and server output filters do the best effort at keeping the streaming process going while they are signing or encrypting the payload. JWE JSON client/server output filter and JWS Compact client/server input filters will be enhanced in due time to support the streaming too. Most of CXF JOSE system tests enable the streaming capable filters to stream by default, however this can be disabled.  

JWS and JWE JSON input filters are expected to process JSON containers with the properties set in a random order hence by default they wil not stream the data in.  

Register both JWS and JWE out filters if the data need to be signed and encrypted (the filters are ordered such that the data are signed first and encrypted next) and JWS and JWE in filters if the signed data need to be decrypted first and then verified.

JWS Compact

JwsWriterInterceptor creates compact JWS sequences on the client or server out directions. For example, if you have the client code posting a Book or the server code returning a Book, with this Book representation expected to be signed, then add JwsWriterInterceptor and set the signature properties on the JAX-RS client or server.

JwsClientResponseFilter and JwsContainerRequestFilter process the incoming client or server Compact JWS sequences.

Here is an example of a JSON Book representation being signed and converted into  Compact JWS and POSTed to the target service:

Address: https://localhost:9001/jwsjwkhmac/bookstore/books
Http-Method: POST
Content-Type: application/jose
Payload: 
eyJhbGciOiJIUzI1NiIsImN0eSI6Impzb24ifQ.
eyJCb29rIjp7ImlkIjoxMjMsIm5hbWUiOiJib29rIn19.
hg1T41ESuX6JvRR--huTA3HnbrsdIZSwkxQdyWj9j6c

You can see 3 JWS parts (put on separate lines for the better readibility) separated by dots. The 1st part is Base64Url encoded protected headers, next one - Base64Url encoded Book JSON payload, finally - the signature.

The following client code can be used to set the client JOSE interceptors:

@Test
    public void testJwsJwkBookHMac() throws Exception {
        String address = "https://localhost:" + PORT + "/jwsjwkhmac";
        BookStore bs = createJwsBookStore(address);
        Book book = bs.echoBook(new Book("book", 123L));
        assertEquals("book", book.getName());
        assertEquals(123L, book.getId());
    }
    private BookStore createJwsBookStore(String address, 
                                         List<?> mbProviders) throws Exception {
        JAXRSClientFactoryBean bean = new JAXRSClientFactoryBean();
        bean.setServiceClass(BookStore.class);
        bean.setAddress(address);
        List<Object> providers = new LinkedList<Object>();
        JwsWriterInterceptor jwsWriter = new JwsWriterInterceptor();
        jwsWriter.setUseJwsOutputStream(true);
        providers.add(jwsWriter);
        providers.add(new JwsClientResponseFilter());
        providers.add(new JacksonJsonProvider());
        bean.getProperties(true).put("jose.debug", true);
        bean.setProviders(providers);
        bean.getProperties(true).put("rs.security.signature.properties", 
            "org/apache/cxf/systest/jaxrs/security/secret.jwk.properties");
        return bean.create(BookStore.class);
    }

The above code shows a client proxy code but WebClient can be created instead with a bean.createWebClient() instead.

JwsJsonWriterInterceptor creates JWS JSON sequences on the client or server out directions. 

JwsJsonClientResponseFilter and JwsJsonContainerRequestFilter process the incoming client or server Compact JWS sequences.

JWE

JweWriterInterceptor creates Compact JWE sequences on the client or server out directions. For example, if you have the client code posting a Book or the server code returning a Book, with this Book representation expected to be encrypted, then add JweWriterInterceptor and set the encryption properties on the JAX-RS client or server.

JweClientResponseFilter and JweContainerRequestFilter process the incoming client or server Compact JWE sequences.

JweJsonWriterInterceptor creates JWE JSON sequences on the client or server out directions. 

JweJsonClientResponseFilter and JweContainerRequestFilter process the incoming client or server JWE JSON sequences.

Linking JWT authentications to JWS or JWE content

CXF introduced a "JWT" HTTP authentication scheme, with a Base64Url encoded JWT token representing a user authentication against an IDP capable of issuing JWT assertions (or simply JWT tokens). JWT assertion is like SAML assertion except that it is in a JSON format. If you'd like to cryptographically bind this JWT token to a data secured by JWS and/or JWE processors then simply add JwtAuthenticationClientFilteron the client side and JwtAuthenticationFilter on the server side. These filters link the authentication token with a randomly generated secure value which is added to both the token and the body JWS/JWE protected headers.

This approach is more effective compared to the ones where the body hash is calculated before it is submitted to a signature creation function, with the signature added as HTTP header.

Configuration

CXF JOSE configuration provides for loading JWS and JWE keys and supporting various processing options. Configuration properties can be shared between JWS and JWE processors or in/out only JWS and or JWE properties can be set.

Typically a secure JAX-RS endpoint or client is initialized with JWS and or JWE properties.

For example, this endpoint is configured with a single JWS properties file which will apply to both input (signature verification) and output (signature creation) JWS operations. This endpoint depends on two JWS properties files, one - for input JWS, another one - for output JWS. Similarly, this endpoint uses a single JWE properties file for encrypting/decrypting the data, while this endpoint uses two JWE properties files. This endpoint support both JWS and JSON with in/out specific properties. If either JWS or JWE private key needs to be loaded from the password-protected storage (JKS, encryped JWK)  then a password provider needs be registered as well, it can be shared between JWS or JWS or be in/out specific for either JWS or JWE.

These configuration propertie are of major help when JAX-RS JOSE filters process the in/out payload without the application service code being aware of it. While filters can be injected with JWS or JWE providers directly, one would usually set the relevant properties as part of the endpoint or client set-up and expect the filters load the required JWS or JWE providers as needed. 

If you need to do JWS or JWE processing directly in your service or interceptor code then having the properties may also be helpful, for example, the following code works because it is indirectly supported by the properties indicating which signature or encryption algorithm is used, where to get the key if needed, etc:

JwsSignatureProvider jwsOut = JwsUtils.loadSignatureProvider(true);
JwsSignatureVerifier jwsIn = JwsUtils.loadSignatureVerifier(true);

JweEncryptionProvider jweOut = JweUtils.loadEncryptionProvider(true);
JweDecryptionProvider jweIn = JweUtils.loadDecryptionProvider(true);

The providers may be initialized from a single properties file or each of them may have specific properties allocated to it.

Sometimes it can be useful to load the properties only and check the signature or encryption algorithm and load a JWS or JWE provider directly as shown in JWS and JWE sections above.

Properties jwsProps = JweUtils.loadEncryptionProperties("jws.properties", true);
Properties jweProps = JweUtils.loadEncryptionProperties("jwe.properties", true);

After loading the properties one can check various property values (signature algorithm, etc) and use it to create a required provider.

The above code needs to be executed in the context of the current request (in server or client in/out interceptors or server service code) as it expects the current CXF Message be available in order to deduce where to load the configuration properties from. However JwsUtils and JweUtils provide a number of utility methods for loading the providers without loading the properties first which can be used when setting up the client code or when no properties are available in the current request context.

When the code needs to load the configuration properties it first looks for the property 'container' file which contains the specific properties instructing which keys and algorithms need to be used. Singature or encryption properties for in/out operations can be provided.  

Configuration Property Containers

Signature

Encryption

Note that these property containers can be used for creating/processing JWS and JWE Compact and JSON sequences. If it is either JWS JSON or JWE JSON and you wish to have more than one signature or encryption be created then let the property value be a commas separated list of locations, with each location pointing to a unique signature or encryption operation property file.

Once the properties are loaded the runtime proceeds with initializing JWS/JWE providers accordingly. The following section lists the properties, some oif them being common and some - unique to the signature/verification and encryption/decryption processes.

Note that one can override some of the properties, for example, 'rs.security.store' can be set as a dynamic request property pointing to a preloaded Java KeyStore object.

Configuration that applies to both encryption and signature

Configuration that applies to signature only

Configuration that applies to encryption only

Configuration that applies to JWT tokens only

Interoperability

JOSE is already widely supported in OAuth2 and OIDC applications. Besides that CXF JOSE client or server will interoperate with a 3rd party client/server able to produce or consume JWS/JWE sequences.  For example, see the following WebCrypto API use case, the following demo demonstrates how a JWS sequence produced by a browser-hosted script can be validated by a server application capable of processing JWS, with the demo browser client being tested against a CXF JWS server too. 

Third-Party Libraries

Jose4J

Nimbus JOSE