First quantum crypto bank transfer

Bill Stewart bill.stewart at
Sat Aug 21 23:10:06 EDT 2004

At 01:00 PM 8/21/2004, Florian Weimer wrote:
>However, I still don't believe that quantum cryptography can buy you
>anything but research funding (and probably easier lawful intercept
>because end-to-end encryption is so much harder).

I agree that it doesn't look useful, but "lawful intercept" is harder,
if you're defining that as "undetected eavesdropping with
possible cooperation of the telco in the middle",
because quantum crypto needs end-to-end fiber so there's
nothing the telco can help with except installing dark fiber,
and the quantum crypto lets you detect eavesdroppers.

On the other hand, at least in the US and probably in Germany,
if the government wants the records of a bank's transactions,
all they need is the locally-proper paperwork demanding the data,
which is a threat model that quantum crypto doesn't help with,
especially since the costs of that attack are much lower than
tapping quantum fiber transactions.

An intermediate level of weakness is detection of who
the bank is communicating with.  In the case of quantum crypto,
it's simple - just follow the fiber to the other end.
But banks are a semi-special case for this threat also,
because you know that a bank's headquarters will talk to
other buildings belonging to that bank, so it's no information leak...

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