Rewrite the extension code to use an ASN1_ITEM structure
for its ASN1 operations as well as the old style function
pointers (i2d, d2i, new, free). Change standard extensions
to support this.

Fix a warning in BN_mul(), bn_mul.c about uninitialised 'j'.

reliable timings yet, please try it out!

course, that means we need to handle the cases where the two arrays to
bn_mul_recursive() and bn_mul_part_recursive() differ in size.

I haven't yet changed the comments that describe bn_mul_recursive()
and bn_mul_part_recursive().  I want this to be tested by more people
before I consider this change final.  Please test away!

bn_add_words(), not bn_sub_words()...

BN_mul() correctly constified, avoids two realloc()'s that aren't
really necessary and saves memory to boot.  This required a small
change in bn_mul_part_recursive() and the addition of variants of
bn_cmp_words(), bn_add_words() and bn_sub_words() that can take arrays
with differing sizes.

The test results show a performance that very closely matches the
original code from before my constification.  This may seem like a
very small win from a performance point of view, but if one remembers
that the variants of bn_cmp_words(), bn_add_words() and bn_sub_words()
are not at all optimized for the moment (and there's no corresponding
assembler code), and that their use may be just as non-optimal, I'm
pretty confident there are possibilities...

This code needs reviewing!

stdout.  bc gets so confused by bean counts.

two functions that did expansion on in parameters (BN_mul() and
BN_sqr()).  The problem was solved by making bn_dup_expand() which is
a mix of bn_expand2() and BN_dup().

that of the result pointer to bn_mul was the same as one of the two arguments,
That argument might have it's sign destroyed.  He provided this fix.

temporary BIGNUMs. BN_CTX still uses a fixed number of BIGNUMs, but
the BN_CTX implementation could now easily be changed.

but the BN code had some problems that would cause failures when
doing certificate verification and some other functions.

Submitted by: Eric A Young from a C2Net version of SSLeay
Reviewed by: Mark J Cox
PR: