Support fast field inversion for P-256, P-384, and P-521 #4209
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The bad news is the savings are pretty weak overall. The good news is that suggests that a 5 bit fixed window is nearly as good as using the best known addition chain, so there isn't much need to do this for the other curves. |
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reneme
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For P-256 this speeds up projective->affine conversion by about 5%, saving ~2K cycles. For P-384 it speeds up conversion by 25%, saving 8K cycles. For P-521 it speeds up conversion by 20%, saving 33K cycles. The savings are most pronounced with ECDSA signing (since it is the fastest operation), improving by 2%, 4%, and 2% resp. GH #4027
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For P-256 this speeds up projective->affine conversion by about 5%, saving ~2K cycles.
For P-384 it speeds up conversion by 25%, saving 8K cycles.
For P-521 it speeds up conversion by 20%, saving 33K cycles.
The savings are most pronounced with ECDSA signing (since it is the fastest operation), improving by 2%, 4%, and 2% resp.
GH #4027 #1479