Hi guys, I am a newby so if this post must be relocated to a different section do not hesitate to let me know!

Since I am new in this world I was reading documentation last days. I read as well the official documentation of SHA-3 keccak protocol (I know most of cryptocurrency are still using SHA-2 protocol for hashing), and I know that parallel computing was optimum for SHA-2 protocol, since GPU enabled a much faster proof of work than CPU.

Does anyone knows if paralel computing can speed up hashing for SHA-3 keccak protocol? In any case I would thank a technical, computational explanation.

Thanks in advance,

Sergi.

Thanks everyone for the answers, now I do understand.

Thanks for your answer,

My question is precisely about this point: "Then they perform a double SHA256 hash of the header". If I understand properly SHA256 algorithm starts with a string that throughout a mathematical operation over such string gives a result that must satisfy that result<target, i.e H(x)=y<target, where H(·) is such operation, 'x' is the string and 'y' the result. Who decides what is the string 'x' to solve?

I mean proof of work is all about solve a challenge. Whenever a new block is find, a new challenge is 'put on the table' so that all nodes are trying to solve the same challenge. Who puts on the table that new challenge anytime is needed? Is it decided by the protocol SHA256 based on the last block accepted in the blockchain?

Thank you!

Sergi

Hello everyone,

First of all I would like to say that I am a newby here, so I would much appreciate that in case I do any mistake or breaking of the forum laws, you would point it out.

My question is as it introduced in the Subject: Since Bitcoin is based on a decentralized system who decides the proof of work that must be solved so that it gets tied to the blockchain? I guess it is based on some criteria that when any node receives the last block of the chain it can by itself calculates which it is the new proof of work, hence it is a function based in the last blockchain that gives an unique solution: f(B1)=New proof of work. If I am right what is that function? Otherwise how does it works?

Thanks in advance,

Sergi