[liberationtech] Feds put heat on Web firms for master encryption keys

[Yan Zhu]

On Thu, Jul 25, 2013 at 12:41 PM, Ben Laurie <ben at links.org> wrote:

> On 25 July 2013 11:22, Nick <liberationtech at njw.me.uk> wrote:
> > On Thu, Jul 25, 2013 at 11:19:22AM +0200, Eugen Leitl wrote:
> >> (See also https://en.wikipedia.org/wiki/Convergence_(SSL) )
> >
> > Would Convergence help here? I can't see how. If a government
> > secretly aquired the SSL private keys for a site, and the site
> > continued using them, then no convergence notary would know any
> > cause not to vouch for the key.
>
> What helps here is perfect forward secrecy.
>

It's worth remembering that SSL is primarily used as a means of protecting
data in transit, not data at rest; PFS doesn't help for the latter because
SSL-encrypted traffic is decrypted before it gets stored on a company's
servers (in order to be useful for queries and such).

I had difficulty finding information about company policies for protecting
data at rest, but anecdotally, they seem to mostly vary from "stored in
plaintext in a password-protected database" to "stored in plaintext in a
password-protected database behind a firewall." In other words, even with
PFS-supporting SSL, there is still a centralized and persistent attack
point for user data. My intuition is that if PFS becomes more popular,
federal agencies will simply shift resources to obtaining access to data at
rest.

(I wrote about this in more detail
here<http://zyan.scripts.mit.edu/blog/some-thoughts-on-facebook-implementing-forward-secrecy/>in
response to the announcement of Facebook implementing PFS.)

Dialogue and links suggesting otherwise would be much appreciated.

-Yan

PS: Does anyone actively use convergence? The original repository hasn't
been updated in a year. I installed a patched version of it in the latest
FF from Github and immediately had to open this
ticket<https://github.com/moxie0/Convergence/issues/176>.




>
> BTW, better alternative to Convergence: Certificate Transparency -
> http://tools.ietf.org/html/rfc6962.
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-- 
Yan Zhu
http://web.mit.edu/zyan/www/
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