Presently all post-quantum *key agreements* registered for TLS are (essentially) ML-KEM. If ML-KEM is broken, then a TLS connection even using SLH-DSA can be decrypted passively and can also be actively MitMed. From a security standpoint, I see little value in using SLH-DSA over (hybrid) ML-DSA unless you also use a different key agreement.
I'm not against SLH-DSA in TLS in the future, but it's very far down on the priority list. Best, Bas On Tue, Jul 15, 2025 at 12:07 AM Sean Turner <[email protected]> wrote: > We kicked off an adoption call for Use of SLH-DSA in TLS 1.3; see [0]. We > called consensus [1], and that decision was appealed. We have reviewed the > messages and agree that we need to redo the adoption call to get more input. > > What appears to be the most common concern, which we will take from Panos' > email, is that "SLH-DSA sigs are too large and slow for general use in TLS > 1.3 applications". One way to address this concern is to add an > applicablity statement to address this point. We would like to propose that > this (or something close to this) be added to the I-D: > > Applications that use SLH-DSA need to be aware that the signatures sizes > are large; the signature sizes for the cipher suites specified herein range > from 7,856 to 49,856 bytes. Likewise, the cipher suites are considered > slow. While these costs might be amoritized over the cost of a long lived > connection, the cipher suites specified herein are not considered for > general use in TLS 1.3. > > With this addition in mind, we would like to start another WG adoption > call for draft-reddy-tls-slhdsa. If you support adoption with the above > text (or something similar) and are willing to review and contribute text, > please send a message to the list. If you do not support adoption of this > draft with the above text (or something similar), please send a message to > the list and indicate why. This call will close at 2359 UTC on 28 July 2025. > > Cheers, > Deirdre, Joe, and Sean > > [0] https://mailarchive.ietf.org/arch/msg/tls/o4KnXjI-OpuHPcB33e8e78rACb0/ > [1] https://mailarchive.ietf.org/arch/msg/tls/hhLtBBctK5em6l82m7rgM6_hefo/ > [2] https://datatracker.ietf.org/doc/draft-reddy-tls-slhdsa/ > _______________________________________________ > TLS mailing list -- [email protected] > To unsubscribe send an email to [email protected] >
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