microsoft
Remove custom COSE header decoding code
The t_cose 1.x release does not support decoding of custom header parameters. This functionality however is part of the dev branch of t_cose which will become 2.x.
As we need custom parameters, we currently decode the header ourselves in app/src/cose.h. Once t_cose 2.x or a pre-release of it is out, we can upgrade and remove the custom code.
As a side note, now that CCF vendors t_cose, if we update to CCF 3.x we'll be restricted to whatever version they are using. They might object to using a pre-release version.
(In fact I tried to build with CCF 3.x and it failed because the t_cose version they use doesn't have the EdDSA support, I need to get them to update).
CCF will object to using pre-releases. But it also has some code to support custom header parameters it'd rather do without, and will therefore gladly upgrade to t_cose 2.x releases, as soon as they become available.
There is little sign of t_cose 2.x converging. We can revisit this if it happens, and perhaps consider the rest of the cose library landscape when we do.