NULL. Remove the non-null checks from callers. Save much code.
[Rich Salz]
+ *) Add secure heap for storage of private keys (when possible).
+ Add BIO_s_secmem(), CBIGNUM, etc.
+ Contributed by Akamai Technologies under our Corporate CLA.
+ [Rich Salz]
+
*) Experimental support for a new, fast, unbiased prime candidate generator,
bn_probable_prime_dh_coprime(). Not currently used by any prime generator.
[Felix Laurie von Massenbach <felix@erbridge.co.uk>]