Cell Phone Encryption?

Black Diamond asks: "I know I'm not up to speed on cell phone encryption, but I was wondering, are there any cell phones that let you handle the encryption from your end of things? Something along the lines of a phone you hook up to your computer to input specific encryption keys for specific contacts, as well as a private key for yourself. Is such a thing plausible, or should you trust the standard encryption that comes on some cell phones nowadays?"

Re:legal phone tapping

[shakah]

This would prevent law enforcement agencies tapping the signal.

Strictly speaking, LEA's could still "tap", encryption would just make it more difficult to make sense of the captured voice stream (in the case of a voice intercept, that is). And even with "user encryption", you could still service "pen register" and "trap and trace" warrants (basically timestamped records of who called who).

Furthermore, though I can't find the reference now, I remember reading that carriers are permitted to offer "unreversible" encryption on their networks (i.e. if they are able to decrypt the communication they have to do it when faced with an appropriate warrant, but if they can't they are still in compliance with CALEA).

Re:GSM phones encrypt anyway - NOT

[Splork]

No they don't.

(a) Both GSM and CDMA encryption are flawed and can be broken.

(b) It doesn't matter if the encryption is bad, all GSM phones listen for a single bit from the tower they're communicating with that tells it if it should encrypt or not. It is trivial for anyone with the resources to eavesdrop on a digital phone call to setup their own fake tower to tell your phone to turn encryption off.

(c) so what if mobile phones encrypt, phone lines that they connect to don't.

never trust commercial "encryption" to be anything more than the magic decoder ring from your cerial box wrapped in a DMCA wrapper calling anyone that points out that its made of cheap injection molded plastic an information terrorist.