Tapping the link can be done passively - no warrant, no paid-off corporation, 
no undercover government agents posing as ISP employees.

Tapping at the end requires one of these things. Nothing has been said about 
key exchange and/or authentication.


On Nov 5, 2013, at 12:48 PM, Eric Burger 
<[email protected]<mailto:[email protected]>>
 wrote:

I do not see how this can help. In fact, I see this as a very DANGEROUS 
proposal.

The reason is precisely because all this proposal does is mean that ONLY the 
NSA, GCHQ, MSS (PRC), and GRU gets to analyze all data. Worse, their secrets 
stay secret, so there is no accountability.

Why do I say this? Because these organizations have the capability to take the 
full firehose. They do not need to tap anything, they just insert an extra 
router and they are in. No need for messy warrants, paid-off corporations, or 
undercover ISP employees that are actually in the employ of the government.

I do not get how link encryption helps at all. Please illuminate.

On Nov 5, 2013, at 10:01 AM, Phillip Hallam-Baker 
<[email protected]<mailto:[email protected]>> wrote:


One of the handicaps we are working under is that the IETF is historically the 
ARPANET 'End to End' working group and we define the Internet stack from the IP 
layer up.

Some problems can't be addressed at the IP layer, in particular it is 
impossible to address traffic analysis efficiently or pervasively. Tor is very 
good at what it does but Tor can't support three billion users doing streaming 
video under any imaginable circumstances.

A much better option would be to tell every network vendor that they have to 
build full speed encryption/decryption capability into every link adapter and 
exchange encrypted data all the time the fiber is lit. The protocol for 
establishing the link layer encryption need not be very fancy. It arguably does 
not even need to be proof against a man in the middle attack since any man in 
the middle is going to be forced to drink the whole fire hose.

There are devices for encrypting OC-768 40Gbit links today. But they are niche 
products made for NSA use (now where does all that data come from??). AES in 
standard cell does not add a huge number of gates to a circuit. Vendors need to 
be trained to believe that they have to add it to every chip or won't be able 
to sell the product.

On circuit encryption is potentially much better against traffic analysis in 
any case since if you bolt a hardware encryptor onto a link and feed it data, 
it is likely that the timing of bits at least provides hints for a timing 
attack.

Such a scheme would be in no way a replacement for end-to-end encryption. And 
there would be an issue of collusion with the carriers and governments. But 
reducing the attack surface from every government who can rent a back hoe to 
one government with a subpoena is very powerful. And forcing the intelligence 
agencies to collude to perform traffic analysis would further limit 
capabilities.

The payoff for this effort is a major increase in work factor and in 
particular, forcing an adversary attempting a traffic analysis attack to 
intercept and decrypt multiple fire hoses. 40Gb/sec is quite a lot of data to 
store. It is over an exabyte per link per year. Or about a quarter million 4Tb 
hard drives. Or $200 million at $500 per drive (including racking etc.)

And that is per link.

The NSA budget is in the tens of billions a year. So we can eat up the whole 
pie by encrypting 50-500 links. Or the entire military budget would be 5,000 
links. The only feasible attack would be to suborn the fab. But I expect that 
there will be a presidential executive order prohibiting that type of sabotage 
under the next President recognizing the fact that the cost of such activities 
in terms of damage to trust in international commerce is vastly greater than 
the benefit to the boasting generals careers.


40Gb/sec is not a vast quantity of data to encrypt with hardware support. Not 
for a device that is all custom VLSI anyway by its very nature. If the fiber is 
lit it is going to take the same power whether it sends all zeros or a mixture 
of ones and zeros.

There would be a small degree of additional complexity introduced by the need 
to conceal the sizes of the underlying packets.


It would not be a perfect defense against every attack and there is still the 
possibility that the attacker would persuade data to be sent over unencrypted 
links and such. But it would establish a gratifying increase in work factor 
which is the objective here.

--
Website: http://hallambaker.com/
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