[ PRIVACY Forum ] Toward Pervasive Internet Encryption:

privacy at vortex.com privacy at vortex.com
Tue Dec 11 03:49:52 PST 2007

Unshackling the Self-Signed Certificate
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  Toward Pervasive Internet Encryption: Unshackling the Self-Signed  


Greetings.  In "http: Must Die! (and The Encryption Solution)"
( http://lauren.vortex.com/archive/000338.html ), I suggested an
accelerated move toward the routine use of encrypted TLS/https:
instead of unencrypted http: for Web communications.

An issue that cannot be ignored in this regard is the cost and
logistics of server security certificates that are natively
recognized by popular Web browsers.

Certificates are required to enable TLS encryption in these
environments, of course.  And while the marketplace for commercial
certs is far more competitive now than it was just a few years ago,
the cost and hassle factors associated with their purchase and
renewal are very relevant, especially for larger sites with many
operational server names and systems.

What isn't widely understood outside of the technical community is
that "self-signed" certificates, which can be generated for free by
anyone (and with essentially arbitrary expiration dates) can enable
these cryptographic systems in a manner very similar to commercial
certs.  What self-signed certs typically won't provide is the same
"web of trust" confirmation (via a widely recognized certificate
authority) for the *identity* of a given site.

However, in a vast number of applications where absolute identity
confirmation is not required (particularly when commerce is not
involved), self-signed certificates are quite adequate.

Why then are self-signed certs primarily employed within
organizations, but comparatively rarely for servers used by the
public at large, even where identity confirmation is not a major

The primary reason is that most Web browsers will present a rather
alarming and somewhat confusing (for the typical user) alert as part
of a self-signed certificate acceptance query dialogue.  This tends
to scare off many people unnecessarily, and makes self-signed
certificate use in public contexts significantly problematic.

Security purists may bristle at what I'm going to say next, but so
be it.  I believe that we should strongly consider something of a
paradigm shift in the manner of browsers' handling of self-signed
certificates, at the user's option.

When a browser user reaches a site with a self-signed certificate,
they would be presented with a dialogue similar to that now
displayed, but with additional, clear, explanatory text regarding
self-signed certificates and their capabilities/limitations.  The
user would also be offered the opportunity to not only accept this
particular cert, but also to optionally accept future self-signed
certs without additional dialogues (this option could also be
enabled or disabled via browser preference settings).

If the user declined this option, the browser would continue to
treat self-signed certs in the traditional manner.  If the option
were accepted, future self-signed certs would not trigger the query

In either case, the use of a self-signed certificate would ideally
cause the appearance throughout that session of an appropriate
unobtrusive but clearly visible "self-signed cert" notification
message or icon.  I would also recommend that the browser URL
address bar change to a unique color (e.g. light blue or some other
acceptable choice) to indicate a self-signed certificate in use.

There are obviously significant security ramifications to this
proposal to be carefully analyzed, and a range of variations in the
ways that something along these lines might be implemented.

But I hope that this discussion helps to stimulate explorations
regarding the possible desirability and practicality of much larger
scale use of self-signed certificates on the Internet, particularly
to encourage the transition of routine Web browsing to an encrypted

Lauren Weinstein
lauren at vortex.com or lauren at pfir.org
Tel: +1 (818) 225-2800
Co-Founder, PFIR
    - People For Internet Responsibility - http://www.pfir.org
Co-Founder, NNSquad
    - Network Neutrality Squad - http://www.nnsquad.org
Founder, PRIVACY Forum - http://www.vortex.com
Member, ACM Committee on Computers and Public Policy
Lauren's Blog: http://lauren.vortex.com

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