perhaps PEM could use many different, independent, non-hierarchical CAs.
This is where PGP's supporters attack PEM. It is almost certain that if a
single, corruptible entity has control over signatures, private messages, etc,
that it will be corrupted, whether by large companies or individuals working
for the CA. On the other hand, if, for instance, there were ten or fifteen
independent CAs, then it would be prudent to check several of them before
sending an important message. It would also be possible.
(Unlike the current model.)
Kragen
(P.S. I wrote this without the benefit of an editor, and apologize.)