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[Plants] Re: Higher forgery resistance almost for free?

Bas Westerbaan <bas@cloudflare.com> Wed, 20 May 2026 10:08 UTC

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From: Bas Westerbaan <bas@cloudflare.com>
Date: Wed, 20 May 2026 12:08:06 +0200
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Subject: [Plants] Re: Higher forgery resistance almost for free?
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> This is particularly relevant for airgapped CA deployments where external
> randomness is not an option. A CA-chosen randomizer from compliant hardware
> is the primary viable path, so getting the source requirements right
> matters.
>

We don't need fresh randomness for each randomizer. CAs could generate a
secret key K for that log once, and use H(K, leaf index) as randomizer. Or
why not both: add in some randomness rnd as well: H(K, rnd, leaf index).
This is what's done in ML-DSA to generate the randomness required for a
signature. In any case your point stands: a little extra guidance is needed.

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