the BN library more generally useful.

Submitted by: Douglas Stebila

PR: 1270

keep disclaiming narrower than 32-bit support.

it from mkdef.pl.

saves a bit of space and avoids a compiler warning about string length.

is defined on Windows CE targets.

assembler implementation.

        -Wmissing-prototypes -Wcomment -Wformat -Wimplicit -Wmain -Wmultichar
        -Wswitch -Wshadow -Wtrigraphs -Werror -Wchar-subscripts
        -Wstrict-prototypes -Wreturn-type -Wpointer-arith  -W -Wunused
        -Wno-unused-parameter -Wuninitialized

compiler vendors.

timing attacks.

BN_FLG_EXP_CONSTTIME requests this algorithm, and this done by default for
RSA/DSA/DH private key computations unless
RSA_FLAG_NO_EXP_CONSTTIME/DSA_FLAG_NO_EXP_CONSTTIME/
DH_FLAG_NO_EXP_CONSTTIME is set.

Submitted by: Matthew D Wood
Reviewed by: Bodo Moeller

(Also improve util/ck_errf.pl script, and occasionally
fix source code formatting.)

there's no need to undefine it here.  Then, let's get a bit paranoid
and not define BN_ULLONG on THIRTY_TWO_BIT machines when BN_LLONG
isn't defined.

useful anyway

The function rsa_eay_mont_helper() has been removed because it is no longer
needed after this change.

- possibility of re-creation of the blinding parameters after a
  fixed number of uses (suggested by Bodo)
- calculatition of the rsa::e in case it's absent and p and q
  are present (see bug report #785)
- improve the performance when if one rsa structure is shared by
  more than a thread (see bug report #555)
- fix the problem described in bug report #827
- hide the definition ot the BN_BLINDING structure in bn_blind.c

("perl util/ck_errf.pl */*.c */*/*.c" still reports many more.)

  and BN_get_sign
- implement BN_set_negative as a function
- always use "#define BN_is_zero(a) ((a)->top == 0)"

ec_curve.c (unify comments, etc).

Submitted by: Nils Larsch
Reviewed by: Bodo Moeller, Geoff Thorpe

- Remove unused and unuseful debug cruft.
- Remove unnecessary 'top' fudging from BN_copy().
- Fix a potential memory leak and simplify the expansion logic in
  BN_bin2bn().

Submitted by: Nils Larsch
Reviewed by: Geoff Thorpe

corresponding headers are only required for API functions or structure
details. This now includes the bignum types and BUF_MEM. Subsequent commits
will remove various dependencies on bn.h and buffer.h and update the
makefile dependencies.

- Remove some unnecessary "+1"-like fudges. Sizes should be handled
  exactly, as enlarging size parameters causes needless bloat and may just
  make bugs less likely rather than fixing them: bn_expand() macro,
  bn_expand_internal(), and BN_sqr().
- Deprecate bn_dup_expand() - it's new since 0.9.7, unused, and not that
  useful.
- Remove unnecessary zeroing of unused bytes in bn_expand2().
- Rewrite BN_set_word() - it should be much simpler, the previous
  complexities probably date from old mismatched type issues.
- Add missing bn_check_top() macros in bn_word.c
- Improve some degenerate case handling in BN_[add|sub]_word(), add
  comments, and avoid a bignum expansion if an overflow isn't possible.

bignums are passed in and out of functions and APIs in a consistent form
has highlighted that zero-valued bignums don't need any allocated word
data. The use of BN_set_word() to initialise a bignum to zero causes
needless allocation and gives it a return value that must be checked. This
change converts BN_zero() to a self-contained macro that has no
return/expression value and does not cause any expansion of bignum data.

Note, it would be tempting to rewrite the deprecated version as a
success-valued comma expression, such as;
   #define BN_zero(a) ((a)->top = (a)->neg = 0, 1)
However, this evaluates 'a' twice and would confuse initialisation loops
(eg. while(..) { BN_zero(bn++) } ). As such, the deprecated version
continues to use BN_set_word().

once in the source (where it is set for the benefit of no other code
whatsoever). I've deprecated the declaration in the header and likewise
made the use of the flag conditional in bn_lib.c. Note, this change also
NULLs the 'd' pointer in a BIGNUM when it is reset but not deallocated.

(ie. where top may be zero, or it may be one if the corresponding word is
set to zero). Note, this only affects the macros in bn.h, there are probably
similar corrections required in some c files.

Also, clarify the audit-related macros at the top of the header. Mental
note: I must not forget to clean all this out before 0.9.8 is released ...

tolerance of ambiguous zero-representation, it just improves
BN_abs_is_word() and simplifies other macros that depend on it.

pseudo-random data for each bn_pollute().

bn_correct_top(), previously only bn_check_top() did this.

constant BIGNUMs. It turns out that this trips up different but equally
useful compiler warnings to -Wcast-qual, and so wasn't worth the ugliness
it created. (Thanks to Ulf for the forehead-slap.)

is itself experimental, and in addition may cause execution to break on
existing openssl "bugs" that previously were harmless or at least
invisible.

and structures as constant without having to cast away const at any point.
There is still plenty of other code that makes gcc's "-Wcast-qual" unhappy,
but crypto/bn/ is now ok. Purists are welcome to suggest alternatives.

except internally to the allocator BN_CTX_new(), as such this deprecates
the use of BN_CTX_init() in the API. Moreover, the structure definition of
BN_CTX is taken out of bn_lcl.h and moved into bn_ctx.c itself.

NDEBUG should probably only be "forced" in the top-level configuration, but
until it is I will avoid removing it from bn_ctx.c which might surprise
people with massive slow-downs in their keygens. So I've left it in
bn_ctx.c but tidied up the preprocessor logic a touch and made it more
tolerant of debugging efforts.