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Comment by wodenokoto | Hacker News Reader

I still don't get it.

If an insecure protocol with an insecure implementation can send messages that others can't read, how is it insecure?

The contest limitations rule out most of the likely attack vectors for breaking the protocol in the real world. It's like saying "Our bank vans are 100% secure. Just try stealing money from them without puncturing our tires or bribing one of our employees."

Thanks - this is the best analogy I've heard so far.

The problem is not whether the protocol is secure - the problem is that there's no way we can tell. Historically, that means that it's likely not to be secure.

With regards this counter-challenge. The crypto here is known to be poor. If this counter-challenge cannot be broken, then it shows that the challenge issued by Telegram is no proof of security.

SO in short,

* we don't know if no one can read the Telegram-encyphered messages,

* the challenge provides effectively zero evidence that it's secure,

* Telegram will proclaim loudly that no one has broken their crypto,

* non-specialists will be fooled by this.

If I haven't answered your question, perhaps you could be more explicit as to what you're not understanding.

This is an excellent answer. You get right to the core of it, quite clearly, which is that this has naught to do with the crypto itself. But that:

> If this counter-challenge cannot be broken, then it shows that the challenge issued by Telegram is no proof of security.

Because the contest eliminates many vulnerabilities that exist in the real world.

The contest framework is identical to Telegram’s (no MITM perspective, no known plaintext, no chosen plaintext, no chosen ciphertext, no tampering, no replay access, etc)

Also no side channel observations.

In real life, a lot of breaks in crypto security come from sidechannel attacks, man-in-the-middle attacks, chosen plaintext attacks, etc. Just posting a small number of already-encrypted messages disallows all of these possibilities.

There are attacks that are possible in the real world that Telegram's (& this example) contest deny. It's like tying a person to a chair, and challenging them to run a marathon, to prove that humans can't run marathons. In the real world, people aren't tied to chairs and humans can run marathons.

It's only secure if attackers have < $2 million in resources, or the contest expires within 2000 years for an attacker with 1 PC. Or... and this is a big OR can't position themselves between you and the recipient.

eg. You aren't using Wifi, your network is fully secured, no one has access to any router along the way, etc.

Lets put it this way, if you're using Telegram / MarlinSpikeGram and you and I are in the same coffeeshop I can read your messages.

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