Re: [Secdispatch] [EXTERNAL]Re: Can Composite sigs move back to LAMPS?

Michael Richardson <> Sun, 19 January 2020 16:59 UTC

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From: Michael Richardson <>
To: Eric Rescorla <>
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Date: Sun, 19 Jan 2020 11:59:18 -0500
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Subject: Re: [Secdispatch] [EXTERNAL]Re: Can Composite sigs move back to LAMPS?
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Eric Rescorla <> wrote:
    mcr> In particular, it seems to me that we could add these multiple
    mcr> entries to certificates, using dummy algorithms, and test them in
    mcr> the field against
    mcr> existing browsers, web servers, IDS, firewalls, etc.

    >> It's not quite clear to me how this would work. As I understand it,
    >> this involves replacing the existing public keys and signatures, in
    >> which case they won't be acceptable to any Web browser (and you in
    >> fact won't be able to get BR-compliant certs)....

    mcr> No, it involves two sets of signatures.
    mcr> The traditional set and the new, yet-to-be-precisely-defined set.

    > Yes, but I had understood these tbe encoded on the wire as if they
    > were a new signature algorithm, with the result that such a
    > certificate would not be verifiable by an existing client.

    > Perhaps we should resolve this question first.

I believe that one proposal was to define a new signature type:
  RSA   -> F { RSA, PQ }
  ECDSA -> G { ECDSA, PQ }

and then, as you say, that would not interoperate at all.

But, I think that another proposal is to introduce the additional signatures
and related book-keeping as extensions, without disrupting the current
signature mechanisms.

Michael Richardson <>ca>, Sandelman Software Works
 -= IPv6 IoT consulting =-