Re: [webauthn] Make signature counters a MAY ? (#1590)

Although supporting de-facto standard payment authorization schemes like EMV/Apple Pay has not been considered by the W3C/FIDO community, signature counters fill a nice role here by adding entropy to such authorizations since these do not use challenge/response protocols. Entropy + Unique request and user data + Locally generated time stamps are thus required in order to handle replays of authorizations in a secure and convenient way. 

**That is, please keep the SHOULD!**

Fun fact: In contrast to authentication, replay in authorization based schemes may actually be a "feature". By enabling _idempotent operation_, retransmissions occurring due to network glitches etc., return the same result data without any internal state changes, potentially adding robustness to payment ecosystems .

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Received on Friday, 17 September 2021 04:15:37 UTC