I beg your pardon, but what are you trying to say has NOTHING to do with reality.
There are NO CODES or passwords or programming which a pilot or any engineer has to do. The software of Vipers are already made and Pakistan has NO PART in it and those softwares once provided cannot be overwritten or modified.
For example, PAF could easily acquire AIM-7 Sparrow Missile from black market back in the 90s. But we never had the "software" of Sparrow missile inspite having the hardware to support it.
Similarly today we have the software to support AIM-120 AMRAAM.
CODES have nothing to do with F-16s mission profile. Iam again attaching a screen shot. For clarification and "sorce" I again asked Air Commodore Kaiser Tufail and his reply was pretty much clear.
As said by cardinal, yes it is a conspiracy theory which originated from people who obviously used to claim that "our F-16s" cannot carry nukes. But in reality our 25 year old Block 15s can integrate state of the art nuclear weapons made at Air Weapons Complex, Wah Cantt and POF.
In a nutshell, iam not forcing anyone to believe me, but one should think being "realistic" and practical while discussing such issues. 
