- Joined
- Dec 19, 2002
- Messages
- 560
So the encryption key is transmitted over the air? Wouldn't a hacker then be able to get it and decode the audio? How does the phone and the tower know which frequency to send information back and forth on?Mike_Oxlong said:I believe you are right but I'm not 100% sure. I do know that there are two ciphers used depending on the country. A51 is the stronger of the two while A52 is the weaker.
The encryption is setup between the base station (rbs) and the mobile equipment (me).
With a proper test set, you can actually decode the audio frames right at the base station.
Half rate channels are available which I guess could be considered a form of compression. With the new adaptive multi rate vocoders, half rate audio doesn't sound half bad and is starting to be implemented on busy sites.
Oh, and what is "half rate audio" ?