Steve Shear <azur@netcom.com> writes:
When I worked at Cylink we developed a product, called SecureCell which combined a standard analog cellphone (NEC I think) and a version of our SecurePhone. Despite the fact that it could thwart any but the most well funded eavesdropping we only sold a handfull. It was quite pricy (about $6,000) and required a small suitcase to tote, but even so only a few gov't agencies (mostly diplomatic) and execs thought it was worth the trouble.
One problem facing such devices are the interruptions caused by cell-to-cell handoffs. These can occur even when stationary. SecureCell, I believe, used off-the-shelf line modems. I've read newer modem technologies (Spectrum and AT&T) have pretty much solved this problem.
There's no reason Eric Blossom's phone encryptor can't be readily adapted to cellular to offer a secure and more reasonably priced cellular encryptor.
Eric's phone I thought operated as a bump in the line for landline. The phone was acting as a speaker and microphone, and also is used to make the connection via tone dial? The `bump' switched to 14.4k modem when you pressed go secure, and did A/D, D/A, encrypt, and decrypt. An encrypting cell-phone would be an interesting project. What about starting from a digital GSM phone - it already has all the A/D, and ability to maintain digital connection across hand-offs. I would have thought the extra hardware would be minimal - a RISC chip with on chip RAM and EPROM to encrypt and decrypt. GSM includes A5 encryption here, so basically the whole design is worked out - all you'd have to do is rip out the A5 chip and replace with a decent encryption system. Anyone know how modular the design is, for instance if it would be possible to give a GSM A5 based cell phone a crypto upgrade using published electrical interface standards? (I want one of those - Nokia phone with IDEA + 2048 bit RSA signatures + DH forward secrecy!) Adam -- print pack"C*",split/\D+/,`echo "16iII*o\U@{$/=$z;[(pop,pop,unpack"H*",<> )]}\EsMsKsN0[lN*1lK[d2%Sa2/d0<X+d*lMLa^*lN%0]dsXx++lMlN/dsM0<J]dsJxp"|dc`