[drupal-devel] OpenId-compatible encryption in PHP

[Mark]

Greetings all,

I've been following the development of OpenId 
(http://www.danga.com/openid/), and I have a few questions regarding the 
practical implementation of it for Drupal.  I realize that one of the 
goals of Drupal is that it can run on a variety of PHP 
installations/configurations.  With that in mind, I'm wondering how 
common variouos encryption libraries are in the realm of PHP installations.

Some of the technologies used by OpenId (or under consideration):
  DSA encryption (using PEM key formatting)
  RSA encryption (under consideration)
  SHA1 encryption
  DER encoding
  BASE64 encoding

I'm vaguely familiar with many of these technologies, and have even used 
several of them. 
SHA1 is natively supported by PHP >= 4.3.0.
BASE64 is natively supported by PHP

As for RSA and DSA, I know that these key types are supported by 
OpenSSL.  Is OpenSSL commonly supported in PHP?  I know that it's fairly 
easy to install, but I also realize that many users don't have control 
over what their server supports.

I suppose I'm doing a survey here to see if an OpenSSL requirement is 
beyond the scope of a Drupal core installation.  If there are PHP-based 
alternatives to OpenSSL that could be bundled with (or linked to from) 
Drupal, please inform me about them.

Thanks for your time,
-Mark