Why (special agent) Johnny (still) Can't Encrypt

http://www.crypto.com/blog/p25/

by packetlss • 15 years ago

115 24 15 years ago

Wistar• 15 years ago

As usual, Matt Blaze is amazing.

marshray• 15 years ago

Travis Goodspeed is a neat guy too. Here are some pics on the girl's toy that defeats the secure radios. http://travisgoodspeed.blogspot.com/2010/03/im-me-goodfet-wi...

calloc• 15 years ago

Not sure if he still does it, but he used to send out GoodFET's free of charge so long as you'd build them. I've used his programmer to program multiple different chips and it is absolutely fantastic.

travem• 15 years ago

Really interesting article. One particular statement caught my eye "many P25 systems … are "rekeyed" at frequent intervals, in the apparent (and basically erroneous) belief that changing encryption keys regularly improves security". My belief was that rekeying was useful in order to limit the "blast radius" if a key was compromised and thus improves security. I'd be interested in finding out why that isn't the case, is it because, as in the article, it introduces more problems that it solves or is there another reason?

capnrefsmmat• 15 years ago

His guide to secure P25 deployment suggests simply rekeying whenever a radio is lost, stolen, or compromised, since in a law enforcement context, key theft is much less likely than in military operations. (Cops don't often get shot down over enemy territory, for example.)

Duff4• 15 years ago

Cops are human, and thus vulnerable to exploitation. Do you seriously think that some gang leader somewhere doesn't have local police radios given to him by cops on his payroll?

Periodic rekeying is like physical inventory or periodic password changes -- it helps you identify compromised assets.

reemrevnivek2• 15 years ago

On a related note, I recently found an Air Marshall's radio on the side of the road. This thing had every channel imaginable. I was staggered by the fact that such a device didn't have any sort of login; the physical device was the whole key.

I turned it in, of course. They were really, really grateful.

Duff4• 15 years ago

Cellphones and other out of band communications make police encryption a joke anyway. Anything really sensitive or controversial will be communicated via phone to avoid being recorded anyway.

The real reason for police agencies wanting encrypted voice traffic is to be less transparent, especially from the press. Modern government wants information to be dribbled out from the PR office.

tptacek• 15 years ago

If the police can't keep informants protected, nobody will inform on violent criminals. There are obviously plenty of reasons why law enforcement secure comms need to be actually secure, not just "Motorola says it honored the secure comms standard" secure.

The stuff that police organizations want to be obscurantist about are almost invariably not encrypted; dash cam videos, disciplinary reports, things like that. Yes, once upon a time some geeky reporters were able to get interesting stories out of radio scanners. That's because we were living in the dark ages, not because police tactical radio traffic should be open to anyone.

Duff4• 15 years ago

Walk into the city desk of any major newspaper and a police scanner is on in the background. It isn't a "geeky" thing at all.

Informants have nothing to do with secure comms... the examples of reasons why secure comms are needed usually center around surveillance of organized crime for since 2001, the terrorists.

Is there a need for secure transmission of limited types of communication? Sure. But 95% of the radio traffic is not secret at all.

sp332• 15 years ago

It's not geeky. In some small towns, everyone listens to the scanner. Occasionally someone will lean on the "talk" button and the town will get some gossip broadcast to all the neighbors :)

tonecluster• 15 years ago

You guys are missing the modifier "once upon a time". It's true: once upon a time, some (at the then once-upon-a-time time) geeky reporters got some interesting stories out of radio scanners. And now, it's not geeky to own a computer. But once-upon-a-time (as in when some of us, yer elders, were kids), it was only geeky people what had them. Anyway, agreed with tptacek, completely.

TorKlingberg• 15 years ago

Partially true, but the police has legitimate reasons to use encrypted communication. They deal with sensitive information that should not be public to everyone.

shabble• 15 years ago

Previous thread at http://news.ycombinator.com/item?id=2874301 although not a lot of comments.

feb• 15 years ago

A big lesson from this post (at least for me) is how much user interface affects security. He references an older paper "Why Johnny Can't Encrypt" (http://www.gaudior.net/alma/johnny.pdf) where the negative impacts of the user interface in PGP 5.0 are analyzed. This is an old lesson which was not taken into account for the secured P25 handsets.

A similar analysis of the certs/SSL protection in browsers would be very interesting too.

Why (special agent) Johnny (still) Can't Encrypt

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