[Confusion]

  Well, if the algorithm is so broken then it should be 
  trivial to break it even with their limitations.

Well, if the house is so badly protected, it should be trivial to break in, even with their limitations[1].

[1] Limitations include: not being allowed within 200m of the house.

[raverbashing]

I disagree

You are allowed access to the encrypted data.

In a real attack you may, depending on the circumstances, only have access to that (at first, at least).

Probably more like "you aren't allowed to destroy any locks or doors to enter the house". Hard, but much different than staying 200m from the house.

[Drakim]

> In a real attack you may, depending on the circumstances, only have access to that (at first, at least).

You misunderstand the whole deal.

When imagining different potential attacks on your house you can't go laying down rules that the burglars have to follow. What if there are special circumstances (that you weren't aware of) that allows the burglars to bypass your restrictions under certain conditions? You plan for the worst case scenario, always!

Take password hashing+salting for instance. You could say that it's actually safe to store plaintext passwords because outsiders don't have credentials to access the database.

You could even run a contest where to say that you will give a million dollars to anybody who can get access and steal the passwords, and then insist that since nobody has claimed that million dollars yet, plaintext passwords are clearly safe.

But we all see how foolish that would be. You plan for the worst case scenario and hash+salt your passwords. You don't plan for the "average case scenario" where "normally attackers don't have access to the database".

[raverbashing]

"When imagining different potential attacks on your house you can't go laying down rules that the burglars have to follow"

Of course. But everything is limited and for each scenario there's a specific chance that will happen. Some RSA key sizes are breakable if you can put a lot of computing power behind.

For example, a house may not be built to withstand tanks, so there's your limitation.

On the other hand, there's a huge likelihood someone will walk past your house and see the door ajar, or try to open it.

So, again, everybody is right to secure against KPA, CPA, etc, BUT don't forget that there may be something easier, and yes, if it resists the deeper attacks it's probably safe against capture of cyphertext.

"But we all see how foolish that would be. You plan for the worst case scenario and hash+salt your passwords"

Sure. But in practice the plaintext + strong DB security may be safer "overall" than a hash + salt on a MySQL with the credentials forgotten in some config.php somewhere.

(It's not an excuse to not hash the passwords, though)

[Drakim]

> Of course. But everything is limited and for each scenario there's a specific chance that will happen. Some RSA key sizes are breakable if you can put a lot of computing power behind.

I can agree with you that bruteforce attacks should not be within the scope of such a bug bounty prize or competition (unless somebody has exposed a flaw that allows for very easy brute forcing).

But that's not what's happening here. What's happening here is that the people running the show are handing out a few pieces of encrypted information and saying that since nobody can crack their stuff using that handed out information, their system is secure. It's easy to be confident in a controlled sterilized environment.

The blogger is pointing out that an attacker could very well have access to a lot more information and functionality than what they are handing out. They are only demonstrating that their system is safe in a "good case scenario" when everything goes as planned. They have not demonstrated that their system is secure if everything doesn't go as planned, if suddenly the attacker found a way to spoof the email messages and send his own prodding cypher, or something to that flavor, which isn't part of the neat little package they have arranged as part of competition.

Saying that "that's most likely not the case, the hackers wouldn't have anymore information or access" just is not a rebuttal to that. It's not a rebuttal to anything, it's just a brain fart.