Topic: Who solved the "Bizantine Generals Problem"? - page 2. (Read 2525 times)

A 51% attack indicates a compromised system.  As soon as it occurs the "generals" will be aware of the exploit as well as an added benefit. Other examples of solutions like "Practical Byzantine Fault Tolerance" (PBFT) algorithm" cannot equally be trusted with a compromised system.

You are correct insomuch as we cannot be 100% reliant upon trusting any proposed solution to the Byzantine Generals Dilemma as every solution is reliant upon trusting that the network or system wasn't compromised.

This is just a statement about security and epistemology in general however.

If 51% is enough then it's not Byzantine Generals problem.

Your professor is correct. Satoshi wasn't the first person to solve the Byzantine fault tolerance dilemma.
Bitcoin is merely one widely used application that has successfully solved the Byzantine generals dilemma.

The first practical solution was represented by Miguel Castro and Barbara Liskov in 1999 with the Practical Byzantine Fault Tolerance" (PBFT) algorithm:
https://dl.acm.org/citation.cfm?doid=571637.571640

With regards to Bitcoin :

http://research.microsoft.com/en-us/um/people/lamport/pubs/byz.pdf

2/3rds deals with communication between untrusted parties where unforgeable written messages aren't in use. Of course Bitcoin messages can be forgeable, but the genius of the system is both the consensus mechanism and the incentive structure both discourage users from doing so and make it increasing more difficult to do so with time.

Thus Bitcoin does solve the Byzantine fault tolerance dilemma until a "51% attack" occurs as the authentic blockchain is trusted until such an event occurs.

Some may suggest that if Bitcoin is dependent upon trusting the validity of the blockchain upon solving the Byzantine generals dilemma it may refute the whole notion of ultimate trust as a 51% attack can happen at any moment. Unlike with multiple messengers or couriers in the original dilemma, blockchain based crypto-currencies use of a public ledger system make immediate acknowledgement and demarcate the attack so the "generals" or users can identify if the message is to be trusted or not. Before a 51% attack occurs you can be probabilistically sure to a certain degree based upon the amount of nodes and time passed that a transaction is valid. If a 51% attack occurs it merely shifts the recognition of these false transactions until shortly after they occur until the attacker is dealt with.

All solutions to the Byzantine's General dilemma are dependent upon trusting a non compromised network or system and with bitcoin the network is decentralized and extremely difficult to compromise.

No. His assumptions are weaker, otherwise we would talk about 33% attack, not 51%.

http://research.microsoft.com/en-us/um/people/lamport/pubs/byz.pdf:

Hello  Come-from-Beyond,

Thanks for the link.
I will purchase and read the paper.

But what's the short answer.
Did Satoshi Nakamoto solve the "Bizantine Generals Problem"? Yes or No

Thanks,
 

http://dl.acm.org/citation.cfm?doid=571637.571640

Hello to all!

I recently gave a talk about Bitcoin to a group of business and university professors, and in that talk I said that Satoshi Nakamoto had solved the "Bizantine Generals Problem".

I had read that from several documents and also heard it from a couple of prominent Bitcoin talkers.
To my surprise, one professor disputed my affirmation, got up, and said that another person had solved it before. He mentioned the name but I forgot it.

Now I'm perplexed about the issue and want to know what the real story is, so I can contact this person and conciliate the truth with him.

Can anybody point me to some authoritative evidence on this subject so I can refute or accept this guy's claim?

Thanks a lot,

Rodrigo