[tor-bugs] #9663 [Tor]: Table-based basepoint multiply optimizations for ntor handshake

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#9663: Table-based basepoint multiply optimizations for ntor handshake
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 Reporter:  nickm                       |          Owner:
     Type:  enhancement                 |         Status:  new
 Priority:  normal                      |      Milestone:  Tor:
Component:  Tor                         |  0.2.5.x-final
 Keywords:  tor-relay performance ntor  |        Version:
Parent ID:  #9662                       |  Actual Points:
                                        |         Points:
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 If you know in advance that you'll be performing a large number of scalar
 multiplications by a given point, you can have an optimized implementation
 of the scalar multiply optimization.
 ([https://www.imperialviolet.org/2013/05/10/fastercurve25519.html Adam
 Langley] explains this better than I am likely to do in this ticket
 description.)  We can take advantage of this in a more-obvious way and a
 less obvious way.

 The obvious place to use this is when we're multiplying by a basepoint in
 order to generate ephemeral keys.  There are a few implementations of this
 technique in libraries we're already talking about; see
 https://github.com/floodyberry/ed25519-donna for one example.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/9663>
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