Explicit check to ensure only 1 signer

[bnonni]

Should we add an explicit check to ensure that there's only 1 signer?

https://github.com/TBD54566975/dwn-sdk-js/blob/fcea84929e12dd3e3ef0e8866b0e592a025786fa/src/interfaces/permissions/handlers/permissions-request.ts#L21-L28

[Cxxshyy]

i can have a look at this with some guidance on how to get started

[thehenrytsai]

The easiest thing to do is to just do a length check against jws.signatures.length, and throw if it's not 1. Bulk of the work is probably just right a test to prove that more than one signature initially was allowed, and no longer allowed.

[rajakash-dev]

https://github.com/TBD54566975/dwn-sdk-js/pull/152

[thehenrytsai]

Already addressed by: https://github.com/TBD54566975/dwn-sdk-js/blob/main/src/core/auth.ts#L45