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$200,000 to the first person to break Telegram

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Re: $200,000 to the first person to break Telegram

#112
post #29

Cryptography Snake Oil Warning Sign #9: Cracking contests. https://www.schneier.com/crypto-gram-9902.html (1999)

In #5, Schneier says "For public-key cryptography, 2048-bit keys have same sort of property; longer is meaningless."

Back in September, he issued a new public key of 4096 bits[1].

1. https://news.ycombinator.com/item?id=6376954

Re: $200,000 to the first person to break Telegram

#113

Earlier quoted context omitted.

Unfortunately, this doesn't mean that it's secure. If someone breaks it, it means it's broken, but if nobody breaks it, it doesn't mean someone else can't break it (or hasn't already).

Agreed, but the tone of the previous discussion was definitely more along the lines of "This could never work, you guys don't know what you're doing." If it proves resilient over 2.5 months of highly motivated attacks (motivated by both the money / "I-Told-You-So" factor), I think that's a fairly strong statement in their favor.

OK, but where the hell are they going to get 2.5 months of highly motivated attacks by highly skilled people? All the people I would want looking at this aren't going to waste such a huge chunk of their time analyzing some random phone app trying to make a name for themselves for a chance at a cash reward.

Bug bounties by big name companies that are actually after bugs rather than publicity haven't miraculously made all their software perfect. And they don't have an end date either.

Re: $200,000 to the first person to break Telegram

#114
post #65

Earlier quoted context omitted.

It will allow you to conduct a man-in-the-middle attack on all encrypted traffic though, which would certainly be enough to read messages in plaintext.

http://core.telegram.org/techfaq#q-how-are-telegram-users-pr...

unauthenticated Diffie-Hellman key agreement is known for MITM attack.

Re: $200,000 to the first person to break Telegram

#115
post #29

Cryptography Snake Oil Warning Sign #9: Cracking contests. https://www.schneier.com/crypto-gram-9902.html (1999)

In #5, Schneier says "For public-key cryptography, 2048-bit keys have same sort of property; longer is meaningless." Back in September, he issued a new public key of 4096 bits[1]. 1. https://news.ycombinator.com/item?id=6376954

If there's anything that's certain, it's the progress of compute power. The fact that his statement lasted 14 years is impressive. I mean, 640K ought to be enough for anyone.

Re: $200,000 to the first person to break Telegram

#116
post #29

Cryptography Snake Oil Warning Sign #9: Cracking contests. https://www.schneier.com/crypto-gram-9902.html (1999)

Marketing Strategy #724: Create Controversy

(regardless of the product, they succeeded in a cheap way to get launched, very likely at a cost of $0)

Re: $200,000 to the first person to break Telegram

#117
post #53

Earlier quoted context omitted.

We already know the system is hopelessly vulnerable to server side MITM attacks, it makes no effort to defend against that attack model. It's mentioned in the comments that they might do manual key verification in the future, but that doesn't happen now. Compromise is silent.

Let me respectfully disagree with you here. Secret Chats in Telegram provide users with a way to detect a server-side MITM attack. http://core.telegram.org/techfaq#q-how-are-telegram-users-pr...

It's simple unauthenticated Diffie-Hellman key agreement, which is known for MITM attack. Yes, you ask A to accept B's identity upon key exchange, but to what extend A would know B is really B not the server playing along? A plausible method would have A and B exchange certificates separate from the Diffie-Hellman key exchange process, and use those as the identity verification mechanism.

Re: $200,000 to the first person to break Telegram

#118
post #68
post #41

Earlier quoted context omitted.

Excluding an entity like the NSA, who cares nothing for $200,000 (literally a rounding error in their budget), but everything for the information available for the taking.

While I agree with your point, immediately jumping to the NSA and their bottomless pool of resources and talent is kind of the new Godwin's law. Logan's law: In any given discussion tangentially related to security, the thing presented as "secure" will be soon declared "definitely not secure"... because...NSA.

I actually agree with the motivation behind your argument -- it's ridiculous to pull out unknown NSA capabilities as a foil to every crypto argument.

I just wanted to point out that there were times when money was not a very good motivator for someone who could break a given encryption system.

Re: $200,000 to the first person to break Telegram

#119
post #29

Cryptography Snake Oil Warning Sign #9: Cracking contests. https://www.schneier.com/crypto-gram-9902.html (1999)

Our Twofish cryptanalysis contest offers a $10K prize for the best negative comments on Twofish that aren't written by the authors. There are no arbitrary definitions of what a winning analysis is. There is no ciphertext to break or keys to recover. We are simply rewarding the most successful cryptanalysis research result, whatever it may be and however successful it is (or is not). Again, the contest is fair because…

1. register numbers close to the target.

2. wait until sender mistypes destination on one message.

3. claim prize.

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