JWE encrypted token support.

To create a JWE, you need to select two algorithms. One is an AES algorithm used to encrypt the content of your token (for example, A128GCM), for which a single-use key is generated internally. The second is used to encrypt this content-encryption key and can be either an RSA or AES-keywrap algorithm. You need to generate a suitable key to use with this, or load one from storage.

AES is much faster and creates shorter tokens, but both the encoder and decoder of the token need to have a copy of the key, which they must keep secret. With RSA anyone can send you a JWE if they have a copy of your public key.

In the example below, we show encoding and decoding using a 2048 bit RSA key pair (256 bytes). If using RSA, use one of the RSA_OAEP algorithms. RSA1_5 is deprecated due to known vulnerabilities.

>>> import Jose.Jwe
>>> import Jose.Jwa
>>> import Jose.Jwk (generateRsaKeyPair, generateSymmetricKey, KeyUse(Enc), KeyId)
>>> (kPub, kPr) <- generateRsaKeyPair 256 (KeyId "My RSA Key") Enc Nothing
>>> Right (Jwt jwt) <- jwkEncode RSA_OAEP A128GCM kPub (Claims "secret claims")
>>> Right (Jwe (hdr, claims)) <- jwkDecode kPr jwt
>>> claims
"secret claims"

Using 128-bit AES keywrap is very similar, the main difference is that we generate a 128-bit symmetric key (16 bytes):

>>> aesKey <- generateSymmetricKey 16 (KeyId "My Keywrap Key") Enc Nothing
>>> Right (Jwt jwt) <- jwkEncode A128KW A128GCM aesKey (Claims "more secret claims")
>>> Right (Jwe (hdr, claims)) <- jwkDecode aesKey jwt
>>> claims
"more secret claims"