Originally Posted by
kreneskyp
A hash is an electronic signature. You take all the data and generate a string (a number really) that represents that data. Depending on the algorithm used the signature can be generated and verified by anyone who knows the algorithm, or it can be limited to only someone (or a device) who possesses the matching cryptographic keys.
Which thread was this talked about in?
Thanks for the insight! Found the other thread/post:
http://www.flyertalk.com/forum/19191361-post184.html
There's also been some somewhat in-depth discussion in the AA forum.
While we can read the cleartext, I should very, very clearly stress that people should NOT tamper with the barcodes. If I find that I'm not going to get PreCheck for a trip, then I'll just deal with regular security and maybe an opt-out, and plan my arrival times accordingly. That extra 10 minutes of my life seems far favorable to whatever I might have to go through if the digital signature no longer matched.