Re: Experimental did:cel Witness Service (open-source)

On Wed, Mar 11, 2026 at 10:38 AM Stephen Curran
<swcurran@cloudcompass.ca> wrote:
> I've been thinking about log size recently, particularly when combined with PQ cryptography.  It seems to me that as we shift to the use of PQ algorithms, the size of the data will be dominated by the keys and signatures, and compression techniques will be much less useful. So if a 10 year log has 5 years of PQ keys and signatures will not benefit much from compression.

Maybe. :)

I expect that keys that are re-used will be compressed greatly,
compression is going to help a lot there (the same public key might be
listed thousands of times, but will only need to go in the compression
table once and from there on out, will take up a few bytes instead of
thousands of bytes).

However, if per-event pre-rotation is in play, you're right --
compression isn't going to help you at all. This is one of the reasons
did:cel doesn't do pre-rotation per event, though did:webvh escapes
the worst of it (I think?) by externalizing the signatures.

My hope is also that SQISign will win out over the current PQ
standards, which have really large key sizes and signature sizes. For
example, SQISign at security level "NIST I" has 64 byte public keys
and 148 byte signatures.

https://sqisign.org/

... which puts it in roughly the same category of storage requirements
as elliptic curve signatures (~2x-ish more storage required for
SQISign signatures, not the ~37x-ish storage needed for MLDSA or the
~122x-ish storage needed for SLHDSA).

But, you're right... if we stick with MLDSA or SLHDSA, the total data
you have to retrieve (no matter the log format) is going to balloon to
37x to 122x. I think, Stephen, did:webvh has a design pattern to get
around this -- can you please remind me what happens there? I know you
externalize into two separate files, but what I'm wondering is if you
have to download both to verify (if you don't cache, that is).

-- manu

-- 
Manu Sporny - https://www.linkedin.com/in/manusporny/
Founder/CEO - Digital Bazaar, Inc.
https://www.digitalbazaar.com/

Received on Wednesday, 11 March 2026 17:46:18 UTC