FAPI not currently compliant with CNSA 2.0

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Originally submitted by josephheenan (Joseph Heenan) on 2026-03-16

As mentioned at IETF OAuth WG call today
https://media.defense.gov/2022/Sep/07/2003071836/-1/-1/0/CSI_CNSA_2.0_FAQ_.PDF disallows the use of SHA256 in favour of SHA-384 or SHA-512 which I believe may means FAPI can't be used in environments that have policies that require CNSA 2.0 compliance (e.g. PKCE requires SHA256).

https://datatracker.ietf.org/doc/draft-skokan-oauth-additional-hashes/ is part of the potential fix for that.

This is probably something we consider as part of general support for post-quantum?

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Bitbucket status: open

Bitbucket origin: issue 856

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Originally submitted by dgtonge (Dave Tonge) on 2026-03-25

on last weeks call, discussion was that no imminent danger, and changing PKCE to sha256 doesn't address post-quantum in and of itself.

we discussed having a policy around post quantum cryptography holistically - not focussed on hash algorithms alone.

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Originally submitted by dgtonge (Dave Tonge) on 2026-04-15

no action immediately for the WG.

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Originally submitted by Nat (Nat Sakimura) on 2026-04-15

We will monitor it, especially for FAPI2.