Re: Signature Algorithm Identifiers

[Ilari Liusvaara <[e-mail]>]

On Fri, Jun 18, 2021 at 04:47:42PM -0400, Justin Richer wrote:
> As discussed on the interim call this week, there’s a proposal for
> changing the algorithm identifiers used in the message signatures
> draft. There was spirited discussion on the topic, which I’ll try
> to summarize here, and it’s been discussed in the following issue:
> 
> https://github.com/httpwg/http-extensions/issues/1510 <https://github.com/httpwg/http-extensions/issues/1510>
> 
> The editors have defined the following identifiers in the current draft, to be used with fully-specified cryptographic algorithms:
> 
> - rsa-v1_5-sha256
> - rsa-pss-sha512
> - hmac-sha256
> - ecdsa-p256-sha256
> 
> Additional algorithms can be defined in an IANA registry, and as stated above, applications are free to use their own signature algorithms without registering a code point.
> 
> The counter-proposal in question (at the issue above) proposes a date-based method for identifiers instead (replacing each identifier in the above list respectively):
> 
>  - rsa-2003
>  - rsa-2005
>  - hmac-2006
>  - ecdsa-2013
> 
>
> The sentiment on the call seemed fairly clear, but the editors are
> seeking feedback and consensus as to whether the registered draft
> should switch to the date-based identifier format as proposed or
> to keep the current labels. 


Another point: Since abstract signatures and abstract MACs exist,
algorithms only really make sense if there are multiple possible
algorithms for a single key (this is usually not cryptographically
kosher). RSA does have two possible algorithms, but looks like HMAC and
(one subtype of) ECDSA only have one.


-Ilari