Refactor Jws and Jwt Verification

[mistermoe]

Overview

Refactored Jws and Jwt Verification into two distinct operations: Decode and Verify

Rationale

we've run into multiple scenarios where we need to:

1. verify a JWT or JWS and then use a number of fields from within the header or the payload/claims
2. decode a JWT or JWS, check some stuff within the payload or headers, and then verify

The way in which Jws and Jwt were initially implemented doesn't let us do this. Additionally, the implementation was a bit obtuse as noted in the TODO here

Changes

In order to remedy the above, this PR splits decoding and verifying into two distinct steps while still providing a single function call if desired

Approach 1

This approach allows to caller to call verify and then decide to perform additional logic using the claims within a JWT depending on the result of verification

decodedJwt = await Jwt.verify('test');

Approach 2

This approach requires the caller to first decode the JWT, perform whatever business logic is needed and then optionally call verify when desired

decodedJwt = Jwt.decode('test');
await decodedJwt.verify();

the Jws public api surface is identical. Simply change Jwt to Jws in the examples above.

Warning

this PR doesn't include enough tests. looking to add some ASAP

[wesbillman]

Should this be ...for JWT signature

[mistermoe]

good catch! fixed ad71b40

[wesbillman]

I'm not sure if it's a big worry here, but since we are reading the crv with a ! there's a chance that would throw when trying to read it and you wouldn't get the nice expectation below.

[mistermoe]

great point @wesbillman . i actually left this as is because i'm removing the entire concept of aliases in the next PR

[wesbillman]

Is there a more specific exception here? Or are both of these changes for header kid?

[mistermoe]

i think we can get slightly more specific. the first exception is thrown if no did resource exists with the kid provided. the second is thrown if the kid provided doesnt point to a VerificationMethod

[wesbillman]

nice!