[tor-bugs] #22006 [Core Tor/Tor]: prop224: Validate ed25519 pubkeys to remove torsion component

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#22006: prop224: Validate ed25519 pubkeys to remove torsion component
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 Reporter:  asn                     |          Owner:  asn
     Type:  defect                  |         Status:  needs_review
 Priority:  Medium                  |      Milestone:  Tor: 0.3.1.x-final
Component:  Core Tor/Tor            |        Version:
 Severity:  Normal                  |     Resolution:
 Keywords:  tor-hs prop224 ed25519  |  Actual Points:
Parent ID:  #21888                  |         Points:
 Reviewer:                          |        Sponsor:  SponsorR-can
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Comment (by asn):

 Here is a review by Yawning:
 {{{
 12:46 < Yawning> the donna code will crash when built with sse2
 12:48 < asn> how do i build with sse2?
 12:49 < Yawning> you do a 32 bit intel build on something modern
 12:49 < Yawning> iirc
 12:49 < Yawning> I don't remember what I did
 12:50 < Yawning> #if defined(__SSE2__) && !defined(CPU_X86_64)
 12:51 < Yawning> or you could add ALIGN(16) in the right place to `
 ge25519 Point, Result;`
 12:52 < Yawning> or since modern x86 has fast unaligned load/stores anyway
 12:52 < Yawning> you could go and change the places that would cause it to
 crash, so the alignment requirement isn't there
 12:53 < Yawning> though I guess people building tor for 32 bit intel are
 running on potatos
 12:54 < Yawning> does doing the validation as part of
 `ed25519_public_from_base64` mean that when parsing the consensus it will
 eventually do
                  several thousand scalar multiplys
 }}}

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/22006#comment:6>
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