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| -rw-r--r-- | README.md | 17 |
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@@ -80,18 +80,19 @@ The current point addition and point doubling algorithms come from the [EFD][]. At least at the moment, we're only interested in ECDSA with the NIST prime curves, so we use algorithms optimized for a=-3. -The point multiplication algorithm is a Montgomery Ladder, which is -not the fastest possible algorithm, but is relatively easy to confirm -by inspection as constant-time. Point multiplication could probably -be made faster by using a non-adjacent form (NAF) representation for -the scalar, but the author doesn't yet understand that well enough to +The point multiplication algorithm is a straightforward square and add +loop, which is not the fastest possible algorithm, but is relatively +easy to confirm by inspection as being constant-time within the limits +imposed by the NIST curves. Point multiplication could probably be +made faster by using a non-adjacent form (NAF) representation for the +scalar, but the author doesn't yet understand that well enough to implement it as a constant-time algorithm. In theory, changing to a NAF representation could be done without any change to the public API. Points stored in keys and curve parameters are in affine format, but -all point arithmetic is performed in Jacobian projective coordinates, -with the coordinates in Montgomery form; final mapping back to affine -coordinates also handles the final Montgomery reduction. +point arithmetic is performed in Jacobian projective coordinates, with +the coordinates themselves in Montgomery form; final mapping back to +affine coordinates also handles the final Montgomery reduction. ## API ## |