Fast constant-time gcd computation and modular inversion
nisse at lysator.liu.se
Mon Jun 6 20:22:59 CEST 2022
Torbjörn Granlund <tg at gmplib.org> writes:
> nisse at lysator.liu.se (Niels Möller) writes:
> Extract least significant 96 bits of each number.
> Is that 3 32-bit limbs or 1.5 64-bit limbs?
I was thinking about 64-bit archs.
Then 96 bits seems to be the maximum number of low-end bits that can be
eliminated, under the constraint that elements of the corresponding
transformation matrix should fit in 64-bit (signed) limbs.
And there's no harm in extracting two full limsb (128 bits), it's just
that the transformation matrix doesn't depend in any way on those extra
For 32-bit transform matrix, one could do less (roughly half, not sure
of it's precicely 48 bits).
Niels Möller. PGP key CB4962D070D77D7FCB8BA36271D8F1FF368C6677.
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