| http://cryptome.org/nsa-fibertap.htm
29 May 2001 Date: Sun, 27 May 2001 21:43:45 -0400 From: Dave Emery <[EMAIL PROTECTED]> To: Steve Bellovin <[EMAIL PROTECTED]> Cc: [EMAIL PROTECTED] Subject: Re: NSA tapping undersea fibers? On Wed, May 23, 2001 at 04:08:34PM -0700, Steve Bellovin wrote: > There's a long, fascinating article in the 23 May Wall Street Journal > on how NSA is (allegedly) tapping undersea fiber optic cables. It's > not clear that this is feasible, but the article claims that the > USS Jimmy Carter, a nuclear-powered sub, is undergoing a $1 billion, > five-year retrofit to equip it to do the taps. The article points out > that even if they can tap the cable, there's another problem: making > sense of that much data. I think the later argument is just as disengenuous as the late 60's Bell System officials who said exactly the same thing about the open unencrypted microwave radio telephone links of that era. Both those microwave links and the undersea fibers contain highly structured and organized information streams - individual voice channels, T1s, T3s, IP streams, wideband data circuits are not at all difficult to extract from the composite traffic and mapping the layout of the whole river of information is by no means overwhelmingly difficult (and might be aided by quiet help from the carriers or individual employees of the carriers). And the mapping tends to be pretty static over time, or at least to change in predictable ways. Finding and recording the most interesting circuits is by no means an insurmountable task - nor is filtering out most of the stuff that isn't interesting. The only hard problem is if the NSA insists on groveling through absolutely everything sent, but this is true of their problem in general these days and not just special to undersea cables. And clearly the right undersea cables contain an awful lot of useful stuff if you are the NSA... And given modern high capacity digital storage systems, handling low gigabytes a second is not that difficult either (most current undersea cable systems only transmit between 2.5 and 20 gigabits a second or so). IO bandwidths in large fast servers are of this order or more these days... The much more interesting problem that gets rather short shrift in the WSJ article is how the real time time critical intercepts get from a submarine hiding in stealth 1200 feet under the ocean to Fort Meade and then to policy makers. Some fraction of the traffic is still interesting after weeks or months when tapes or disks can be flown back to Fort Meade but much more of it is only useful if it is available within seconds or minutes during a crisis and not weeks or months later. Traditional microwave radio and satellite intercepts get back to Fort Meade or the RSOCs in milliseconds but as more and more traffic flows through cables that can only be tapped by hiding billion dollar nuclear submarines a lot of the timeliness of NSA operations goes away. The IVY BELLS tap technology exmplyed against Soviet analog undersea cables in the 70s allegedly involved hooking up a nuclear radioisotope powered pod with tape recorders in it that was left in place for almost a year between submarine visits to recover the tapes - this would be rather hard to do with the gigabytes per second flowing through a modern fiber cable - there is no (unclassified) recording technology with anything like the storage capacity to record everything or even a significant fraction of everything for that long a period in a form factor that would fit in a pod on the sea floor. According to published accounts, in the early Reagan years the intelligence community considered running their own fiber cable to the tap site on the Soviet analog cables to recover the data in real time - I imagine that the same thing has been considered as a solution to the current problem of recovering data from undersea fiber taps while it is still fresh enough to be useful. But in general it is a harder problem than actually tapping the cable or dealing with the rivers of data it contains. -- Dave Emery N1PRE, [EMAIL PROTECTED] DIE Consulting, Weston, Mass. PGP fingerprint = 2047/4D7B08D1 DE 6E E1 CC 1F 1D 96 E2 5D 27 BD B0 24 88 C3 18 |
