Response to NAS Crypto Questions

Adam Shostack, 15 Aug 1994

At the HOPE (Hackers On Planet Earth) conference, there were a pair of AT&T 3600c telephone Surety devices on display & demo. The executive summary is that they sucked. The docs do not mention Clipper at all, but they do have an interesting disclaimer about how AT&T has no responsibility if the government, or anyone else, taps your phone.

The device is $1300.00. This means someone put up 2600 on a credit card. (The conference, organized by 2600 magazine, was much amused.) Each unit includes a 4800 baud feature rich modem, a clipper chip (not marked as such), and some adapters to make it work with various phone handsets. The unit plugs in between the handset and the phone base unit.

The hackers who bought the things had quite a hard time getting them to work at all. There were troubles getting it set up so that it would attempt to go into secure mode, and trouble getting it to do so reliably once a pair of phones that worked were found. AT&T service blamed the problems on line noise, even though the folks testing had a CO simulator, and were able to link modems through it, and also link through the CO.

To make the unit go into secure mode, one person pushes a red button. The unit sends touchtone 2587 (we wern't sure why; someone suggested as a means of calibrating. 258 are in the same row on the phone.) Then the modems do their thing, making modem noises for about 20 seconds (your time may vary; AT&T manual said 10 seconds.) Once connected, the sound is very weak. We in the conference had trouble hearing when the earpiece was right next to a microphone. There was also a roughly quarter second delay (presumably this is for A/D conversion + encryption) in talking. This is a longish delay, roughly equal to an overseas satellite conversation.

Lastly, if you send a dtmf down while in secure mode, you summon the clipper demon, which, we were told, sounds like something out of the exorcist. You also drop out of secure mode. Useful to know if demoing a clipper box. :)

I did not catch the name of the speaker who was doing the demo. A post to alt.hope.d would probably find the info.

[Note: This was "Bernie S." a PA hacker who has had some difficulty with law enforcement of late. AS 28 Jan 95]

There were also two honest to god clipper chips sent by a nice man at Mykrotronix. (Thanks to John Droach(?)) One was kept as by the guy who got them, the other was blown up with a small explosive device to close the conference with a bang. [Aleph One claims responsibility for this. AS 28 Jan 95]

They were quite small; maybe 1 cm square, and .5 cm thick. Manufactured in the Phillipines, too. :)

Anyway, thats my brain dump on clipper from HOPE. There were a fair number of cypherpunks there; anyone else want to offer additions or corrections?


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