tree 278f1835a8dd7b60857f0833bfe4e0702beb1015
parent 8844a3d5464c4632a1374cbb9304aeea61d0166f
author Michael Brown <mcb30@ipxe.org> 1727364297 +0100
committer Michael Brown <mcb30@ipxe.org> 1727441484 +0100

[crypto] Eliminate temporary carry space for big integer multiplication

An n-bit multiplication product may be added to up to two n-bit
integers without exceeding the range of a (2n)-bit integer:

  (2^n - 1)*(2^n - 1) + (2^n - 1) + (2^n - 1) = 2^(2n) - 1

Exploit this to perform big integer multiplication in constant time
without requiring the caller to provide temporary carry space.

Signed-off-by: Michael Brown <mcb30@ipxe.org>