Status of GSM Crypto Attacks

[John Young <jya@pipeline.com>]

Forward from anonymous:

Wed, 21 Oct 98

An engineer at a US wireless telecom and a contributor to 
Cryptologia--has asked me to look into the present status 
of attacks on the GSM encryption schemes:  comp128 (a3a8 
authentication, etc.) and, more importantly, the A5.1 and 
A5.2  voice/data encryption algorithms.

After searching the web, I see that you have similar 
interests in this matter.  I've already sent off inquiries 
to some of the researchers in this area--Ross Anderson, 
Simon Shepherd and the two Berkeley students (Goldberg and 
Wagner).  So far, I've only heard back from Wagner.  Do you 
have anything interesting to say about this matter--has 
anything happened since the Spring?  Has a consensus been 
reached on some of the issues discussed in the 
<http://jya.com/crack-a5.htm> document?

I'm trying to get a handle on the present state-of-the art:  
Where do things presently stand--who is doing the work and 
what, if anything, has been verified/demonstrated?   Has A5 
been cracked?   What can be said about the possibility of 
intercepting and decoding an on-air conversation?