Provide additional variants of bn_add_words()/bn_sub_words().

Move bn_add_words() and bn_sub_words() from bn_add.c to bn_add_sub.c.
These have effectively been replaced in the previous rewrites. Remove
the asserts - if bad lengths are passed the results will be incorrect
and things will fail (these should use size_t instead of int, but that
is a problem for another day).

Provide bn_sub_words_borrow(), which computes a subtraction but only
returns the resulting borrow. Provide bn_add_words_masked() and
bn_sub_words_masked(), which perform an masked addition or subtraction.
These can also be used to implement constant time addition and subtraction,
especially for reduction.

ok beck@ tb@

0 files changed, 0 insertions, 0 deletions