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AffinePoint in LookupTable + NafLookupTable for Shamir's trick #19
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Nashtare
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Use existing methods for cofactor clearing and torsion check
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NAF based scalar mult with a window size of 5 seems to be even more efficient than the regular Lookup based scalar mult, hence relying on this for "vartime" methods. |
baumbata
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Mar 14, 2022
baumbata
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Mar 14, 2022
src/curve.rs
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| i -= 1; |
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Is it more efficient to do it this way than to have e.g. for i in (0..i+1).rev()?
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I believe it's the same, I'm afraid of readability here as i refers to a loop indexed by i, so I instead used for j in (0..i + 1).rev().
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This PR the internal type of points in
LookupTablefromProjectivePointtoAffinePointto benefit from faster mixed-addition. The performance difference is more important for multiplication with the hardcodedBASEPOINT_TABLE, about 13% faster.It also integrates w-NAF conversion of Scalar elements for efficient Shamir's trick, useful in ECDSA or Schnorr signature verification.
The change to
AffinePointas internal type of the LookupTable requires the use oflazy_static!to construct theBASEPOINT_TABLE.closes #13
closes #14