Re: Origin Signed Responses and certificate requirements

On Mon, Apr 09, 2018 at 11:54:26AM +0000, Yoav Weiss wrote:
> Hey all,
> 
> While reviewing the Origin Signed Responses draft, I noticed that the
> certificate
> requirements
> <https://wicg.github.io/webpackage/draft-yasskin-http-origin-signed-responses.html#cross-origin-cert-req>
> section
> requires the signing certificate to have a specific opt-in to response
> signing while also prohibiting such certs from serving TLS connections.
> 
> >From a deployment perspective, the second requirement means that an entity
> which wants to sign packages as well as terminate TLS connections would
> have to maintain multiple certs for each domain, which will significantly
> increase complexity.
> 
> I'm wondering regarding the reasoning behind that second requirement. Why
> can't certs which opt-in to signing packages also be able to serve TLS?
> What are the risks involved?

Specifically, this is because RsaEncryption keys can be used with
insecure static RSA key exchange that will yield a signing oracle
if one gets it even slightly wrong. And such oracles would be very
bad thing in context like this.

In theory, this would not be needed for RSA-PSS, ECC or EdDSA
keys. But this requirement appiles even to them in name of
consistency.


-Ilari

Received on Monday, 9 April 2018 12:14:49 UTC