Add Stir Shaken

[greenpdx]

I have forked the repo and trying to add stir shaken, but I my limited parsing is making it difficult.
The two new filed in sip that I am trying to add are "Identity" and "P-Asserted-Identity"
P-Asserted_Identity is
[Quoted string]Vec URLs are comma separated
Identity is
unquoted string;Vec where string is a base64 JWT, params are semicolon separated (key value pair)

I plan to use a JWT library to parse the JWT

I would like some help with the parsing, I am willing to be coding, testing and and create a PR.

[vasilakisfil]

Hello, sorry for the delay I am swamped with a lot of work lately. If you really want to contribute I would suggest that you go and read up in STIR/SHAKEN and come back with some nice test cases that you can write down in plain text format here (no need to write code). Implementation is the easy part, figuring out what to implement and making sure that the implementation is correct is the hard part. Otherwise, my plan is to add support for it around Christmas.

Leaving this open until we add support.

[greenpdx]

There are 3 parts to testing,
The first part is to generate a valid SS header from URL tel: and sip:. This requires a CA request protocol. For testing the CA protocol only a simple collection would work.
The second is to validate the SIP SS header, correct format for protocol. This is where invalid headers are filtered out.
The third is verification of JWT for calling number again a CA protocol is needed.

I would like to test functionally with.
https://www.atis.org/industry-collaboration/robocalling-testbed/