On Sat, 29 Nov 2003 12:15:56 -0000, Abe wrote:

In article 4xzvb.153$US3.85@okepread03, says...
Basically the system is a challenge/response system. You challenge
the target with an encrypted word. This word is decoded if you have
the right code of the day. The word is changed every challenge, so
in effect, you may get a stream of 100 words, and you have to
decode about 95% of them in your 100 replies, or you will not be
upgraded to friend.

What if a plane was captured, along with its IFF system? Wouldn't that
invalidate the IFFs in every other friendly aircraft?

No, since the enemy would not have the daily codes.

Al Minyard