[Cryptography] Is it mathematically provably impossible to construct a mechanism to test for back doors in programs?

[Phillip Hallam-Baker]

On Fri, Jun 6, 2014 at 10:58 AM, John Kelsey <crypto.jmk at gmail.com> wrote:
>> On Jun 5, 2014, at 9:38 PM, Phillip Hallam-Baker <phill at hallambaker.com> wrote:
>
>
> ...
>> And not a very good one. And there is still no possibility of default
>> that can't be noticed by an external passive audit party.
>>
>> Collusion between the notaries only enables them to rewrite parts of
>> the log that have not been made public already.
>
> This is the critical thing that is necessary.  Even if we somehow get the intelligence agencies and surveillance state in the US under some kind of control, that doesn't deal with the possibility of coercion or bribery against people running important services, by them (extralegally, but the intelligence services in the US seem to be largely above the law) or by private criminals or other governments.  So the services need to be designed to minimize the trust needed for their operators.  The ideal situation is that the operators of the service simply can't do very much harm without being caught--in that case, coercing or bribing them just doesn't pay off, and so it won't be done much.


I have always loved the Harber-Stornetta scheme for this very reason.
The notary is only trusted for the shortest possible interval.
Reinforcing the system is more about ensuring continuity of service
than anything else.

The big challenge has always been putting it to use. BitCoin has
inspired some useful stuff in that regard.

>> The NSA will do a lot when they don't think anyone will notice. The
>> term is 'NOBUS' Nobody but us. They do not do stuff that attracts
>> public attention. Threatening the German and Brazilian governments to
>> unwind a national notary to intercept private communications without a
>> warrant is not going to happen.
>
> This is actually one of the more frightening aspects of the NSA's policies.  There's this bizarre apparent assumption among NSA's defenders that they're going to be the only ones doing this stuff.  Instead, they're helping usher in a world where every government will actively be trying ot subvert security standards and software and coercing weakening of security in their own country.  And since the 800 lb gorilla did it first and was too rich and powerful to push back against, the precedent will be set.  The US will probably lose more than anyone else from this precedent, in the long run.  (As with the precedents we're setting w.r.t. drone warfare and targeted assassination.)  But it's a short-term winner in terms of increasing budgets, getting contracts, and getting elected, so we're probably going to keep doing it regardless of how bad an idea it ultimately is.


Actually no, the US state dept is not bound by NSA precedent.

The way I look at Putin's recent activities is that he is essentially
trying to duplicate the CIA tactics of 1953 and operation Ajax. The
Ukranian communications are probably completely visible to the KGB
because they installed them. So its like a CIA/NSA coup where the
plotters can read all the communications of the target. The use of
agent provocateurs etc was very much like the way the CIA hired thugs
to take down Mossadegh. One of those thugs being the Ayatollah
Khomenei which is why he knew about the coup and Carter did not. And
also the reason he had to get his people into the US embassy to
destroy all the evidence that he was a US tool in the 1953 coup.

But the tactics have moved on since. In 1953 democracy was a
distinctly minority form of government. The US and UK were pretty much
the only countries with more than a century of democratic traditions
and institutions. Most countries were run like Saudi Arabia and about
half the world population had a government like North Korea's.

Today there is no US sphere of influence, the US doesn't need one. 50%
of the world population lives in a liberal democracy. Almost
everywhere else is either getting there or trying to.

We can list the problem countries much quicker than the decent ones.

Being able to poke and pry into other country's communications is
destabilizing. And right now we are the ones interested in stability.