Support for JSON JWE Serialization + SecureEnclave keys + multi-recipient JWE decryption

[Premeide]

Context:

My android + backend is doing two things that Joseswift didnt support:

• Its dealing with multi-recipient JWEs like this: https://connect2id.com/products/nimbus-jose-jwt/examples/jwe-json-multiple-recipients
• And my android is encrypting and decrypting using a hardware backed key (AndroidKeyStore).

Fixes:

• Support for parsing General JWE JSON Serialization Syntax https://datatracker.ietf.org/doc/html/rfc7516#section-7.2.1
• Support for using hardware backed private keys:
  • ECPrivateKey (JWK) can be initialised and decrypt using Secure Enclave key, where private key is non-exportable.
  • 'd' component is therefore optional and new field 'privateKeyHandle' is the referance to SecureEnclave-key
  • (insipired by nimbus' implementation of this https://bitbucket.org/connect2id/nimbus-jose-jwt/src/6a6d0b3d7cf3a7a9830cc8c1e8f54b7a993c706a/src/main/java/com/nimbusds/jose/jwk/ECKey.java#lines-163)
• Support for decrypting multi-recipient JWEs (example A.4.7.):

Other notes:

• README not updated yet

[jenkins-airside]

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