[cryptography] LeastAuthority.com announces PRISM-proof storage service

ianG iang at iang.org
Thu Aug 15 07:23:33 EDT 2013


Yeah.  It's also worth pointing out that it is more or less impractical 
to secure email.  The result is paper-success-reality-fail.  This has 
been an observation for a long time.  For recent evidence see Silent 
Circle's decision to drop their secured email offering.  I would say it 
is mostly because they knew that it is practically impossible and a 
WOFTAM to try to secure email.

The better direction is this:  stop using email, use something like a 
secured chat system, which can be secured, because we can avoid email's 
terrible assumptions and context.

iang


On 15/08/13 14:11 PM, wasa bee wrote:
> To: and From: headers leak the emails/identity of communicating parties,
> but it's not the only place that happens. I've never used PGP but I've
> used SMIME, so I'll refer to SMIME here (that may also apply to PGP
> anyway). In SMIME, the keyWrap (which contains the AES key encrypted
> under each recipient's public key) has some sort of headers that the
> recipient parses. The header contains info about the intended
> recipients' certs, like issuer, SN and email. sometimes it even contains
> the entire recipient's cert (if memory serves). So one has to be careful
> of what info is contained in the keywrap structure. If the email is
> present, it will leak even if To/From were protected somehow. Even if
> the email is not present, maybe the cert info provided for the
> decryption of the keyWrap still leaks enough info about recipients...
> for e.g. it might be enough to identify people by their cert rather than
> by their email.
> Another example where all this matters is in BCC headers. In Firefox
> (last time i checked was 2 years ago i believe), Firefox would send the
> same message to both To,CC and BCC recipients. The BCC header of course
> is not present in the message so recipients don't have access to it.
> However, going thru the keyWrap structure leaks the fact that the
> message has also been encrypted for an extra recipient so it breaks the
> BCC purpose.
>
> It seems to me that as long as a long-term info is transmitted in each
> message, it can be used for tracking who's talking to whom. Or one needs
> to build some sort of deniability into the crypto scheme.
>
>
> On Tue, Aug 13, 2013 at 7:53 PM, ianG <iang at iang.org
> <mailto:iang at iang.org>> wrote:
>
>     On 13/08/13 20:16 PM, Peter Saint-Andre wrote:
>
>         On 8/13/13 11:02 AM, ianG wrote:
>
>             Super!  I think a commercial operator is an essential step
>             forward.
>
>
>         How so? Centralization via commercial operators doesn't seem to have
>         helped in the email space lately.
>
>
>
>     Centralisation works when the server doesn't have any information of
>     value.  Presumably the most that LeastAuthority.com can say is that
>     a certain company has X GB of documents and updates that set at rate
>     Y. Not a lot of value there...
>
>     The reason email space providers are suffering is that even when the
>     content is encrypted, the To: and From are not.  This enables a
>     fairly dramatic capability -- seeing who's writing to whom.  In
>     contrast to the bland GB number, this would provide all a business's
>     customers, all a dissident's contacts, all an insniding trader's
>     leakees, etc etc...
>
>
>
>
>     iang
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