provided by Andrew.

Few cleanups and couple of new things:

 - add SHA2 algorithm to older OpenSSL
 - add BIGNUM math to have public-key cryptography work on non-OpenSSL
   build.
 - gen_random_bytes() function

The status of SHA2 algoritms and public-key encryption can now be
changed to 'always available.'

That makes pgcrypto functionally complete and unless there will be new
editions of AES, SHA2 or OpenPGP standards, there is no major changes
planned.

versions of OpenSSL.  If your OpenSSL does not contain SHA2, then there
should be no conflict.  But ofcourse, if someone upgrades OpenSSL,
server starts crashing.

Backpatched to 8.1.X.

Marko Kreen