thats one of the oldest tricks in the book....fly the other guys flag
shessh...
I do not the details of Mode-5 encryption. I worked on a system that shared an interface with a Mode-5 interrogator. Just an educated guess, but it appears to be a military version of the unencrypted civilian ATCRABS mode-S, or mode-select. In mode S, the interrogator can interrogate a specific aircraft, each of which has a distinct ID number. (There is a mode S “all call” which asks all transponders in a 1.4 degree sector to identify themselves.) The aircraft responds with information requested by the interrogator, in a highly formatted fashion. Similar interface with mode-5, but encrypted.