how secure is secring.pgp?

[Eric Hughes <hughes@soda.berkeley.edu>]

I said:
>>> There are two security items here.  The first is that the secret RSA
>>> key not be revealed.  The second is that the name attached to that
>>> key pair not be revealed.

Marc said:
>I may be nitpicking here, but I have to argue.  Although there is a
>relationship, security and privacy are not one and the same.  You have
>named a security item, and a privacy item, not two security items.

As long as we're being precise, allow me to restate my claim.  If you
use a pseudonym with PGP, and you don't want it revealed, and for some
reason it is revealed (through some other security breach), then the
secret ring has a security failure (lack of encryption) which leads to
a breach of privacy.

The lack of encryption is a material cause of the privacy compromise.
As far as I can tell, I was using security to refer to material causes
and Marc was referring to end results.

>I believe that the secring.pgp is secure, for most reasonable
>purposes.  

So do I.  On an encrypted file system, this is not nearly so large an
issue.  

>>> A parallel (not as consequential): everything about a public key ring
>>> should be encrypted.

A point of clarification for below: that's one's own personal copy of
a public key ring.

>[... this] point is
>ludicrous, IMHO.  If it's a public key, why should it be encrypted?
>The whole purpose of a public key is that it can be widely published.

The point of a public key is that someone else can perform an
operation that only you can undo (and vice-versa, properly stated).
Public keys are for anybody that is not you.  This does not mean that
everyone will have them, or even that everyone should have them.  The
social form of fully published keys need not be the norm.

>You could claim that the keyring
>identified the people with whom I talk, but that is easily overcome by
>just keeping a few thousand people on your keyring.  

If this is the only datum available, that would work.  When another
list is available to intersect your keyring with, the attempted
diffusion may fail unexpectedly.

Keeping your identities of your correspondents private (through a
security mechanism on the keyring) is much the same as using some of
the stronger forms of remailers that have been discussed.

Eric