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Comment by Johnny555 | Hacker News Reader

One way it could be made insecure would be if it didn't use a good source of randomness, so the arrow direction could be predicted. A worst case example would be if the app just cycled through a fixed table of "random" choices like "L R L L R L R R", then the attacker could just watch the pattern and position himself in the line appropriately to make sure that his buddy Joe is the one to screen him. repositioning is easy, just dig through your bag and say to the guy behind you "I can't find my passport, you can go in front of me".

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That problem would be solved by making the app very unstable and require constant restarts ;)

A worst case example would be if the app just cycled through a fixed table of "random" choices

Not even a newbie programmer is going to do this. Every language out there has a Random() function.

Seriously, all these worst case scenarios and we're still well within the land of what even a middling iOS developer could crank out in under an hour.

> Not even a newbie programmer is going to do this.

I wouldn't bet on that. I've seen all sort of horrendous monstrosities that students and new grads have come up with.

You'd be surprised what programmers will do. Sometimes due to incompetence, sometimes it's an "optimization", sometimes it's a simple mistake, yet there is some very bad code out there and it's not discovered until it causes a problem.

For example, even a newbie wouldn't trust a remote client to tell you the size of a string they are sending you so you can echo it back to them, yet we still had Heartbleed and it sat there for a long time, undiscovered.

Which usually isn't cryptographically secure. So now you need to audit the random number generator and make sure that it has no known holes, including obscure edge cases. And then you need to confirm that any implementation is correct and audited.

That quickly takes you down a rabbit hole, which may be why the contract was so expensive.

This is iOS we're talking about. The CSPRNG provided as part of Swift or Obj-C's standard library has likely already been audited for use on other govt. projects.

http://stackoverflow.com/questions/9234686/generating-random...

Great point. Thanks for the link!

Oh you need a cryptographically secure RNG? Assuming the app is written for android just replace Random with SecureRandom. Here's your $100,000 invoice.

And all of this trouble to achieve.....what exactly?

To achieve a "screening" carried out by a co-conspirator, through which weapons, etc. could be passed.

1. The TSA is ineffective at preventing weapons from getting past their security checkpoints.

2. Everything required to make a bomb can be bought past the TSA checkpoint.

3. It would stand to reason that if a terrorist organization can get a conspirator to infiltrate the TSA, they could get, I don't know, two?

4. There's more than one person involved in the screening process.

The fewer people you need to get into the right places at the right time, the more likely your plot is to succeed.

It's not like TSA agents haven't already been caught letting people smuggle contraband past them:

http://www.foxnews.com/us/2015/12/19/tsa-agent-accused-smugg...

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