If SHA-2 is so secure then why? - page 2.

becoin

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Quote from: Man From The Future on July 07, 2011, 08:07:28 AM

They need to make a replacement becqause the alternative is to wait until SHA256 isn't good enough.

I don't reall understand what are you trying to say, Man From The Future. SHA256 is just 1 of the 4 hashing functions that are used in the SHA-2 hashing algorithm!

Quote from: elggawf on July 07, 2011, 07:48:13 AM

It's possible, yes, but it's going to be a mess and require lots of cooperation.

So, better sooner than later because if later the mess will be bigger!

Man From The Future

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Quote from: sirky on July 07, 2011, 08:16:46 AM

It is simply a good idea. SHA-2 is still holding up, but it seems that these hashing functions generally only last so long before someone figures out a way to decrease the attack space enough to make you uncomfortable, or to find a collision fast enough to make you question the theory (MD-4 being the worst).

Updating the client would be a huge mess though. There would have to be a hard coded block (probably) when all the clients switched to whatever the new algorithm was.

Old clients still would be made absolutely useless though, and would create their own block chain at that point.

It would not be good.

Block headers contain a version.

sirky

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It is simply a good idea. SHA-2 is still holding up, but it seems that these hashing functions generally only last so long before someone figures out a way to decrease the attack space enough to make you uncomfortable, or to find a collision fast enough to make you question the theory (MD-4 being the worst).

Updating the client would be a huge mess though. There would have to be a hard coded block (probably) when all the clients switched to whatever the new algorithm was.

Old clients still would be made absolutely useless though, and would create their own block chain at that point.

It would not be good.

natman3400

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firstbits: 1nathana

Quote from: becoin on July 07, 2011, 08:06:16 AM

Quote from: elggawf on July 07, 2011, 07:48:13 AM

You think they should wait until SHA-2 is broken to start looking for a replacement? Think about that for a second.

If they think for a replacement there is a reason, right? If they think for a replacement after 2012 why you shouldn't? Or you intend to use SHA-2 until 2140?

SHA-1 is still unbroken (as far as i know), but that's no reason to not use SHA-2. Just means that SHA-1 had a possible future weakness that could be fixed, for the most part, but at the cost of using more computing power. The time has just come again that average computing power has yet increased that they see fit to upgrade it to nip any possible weakness in the bud. The only problem found in SHA-1 was a POSSIBLE mathematical weakness, and since SHA-2 is roughly based on SHA-1, just a bit beefed up, the search for a replacement to SHA-1 never really stopped.

Man From The Future

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Quote from: becoin on July 07, 2011, 08:06:16 AM

Quote from: elggawf on July 07, 2011, 07:48:13 AM

You think they should wait until SHA-2 is broken to start looking for a replacement? Think about that for a second.

If they think for a replacement there is a reason, right? If they think for a replacement after 2012 why you shouldn't? Or you intend to use SHA-2 until 2140?

They need to make a replacement becqause the alternative is to wait until SHA256 isn't good enough.

Yes, bitcoin can change to not use SHA2

becoin

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Quote from: elggawf on July 07, 2011, 07:48:13 AM

You think they should wait until SHA-2 is broken to start looking for a replacement? Think about that for a second.

If they think for a replacement there is a reason, right? If they think for a replacement after 2012 why you shouldn't? Or you intend to use SHA-2 until 2140?

elggawf

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Quote from: becoin on July 07, 2011, 07:44:44 AM

If SHA-2 is so secure then why have National Institute of Standards and Technology (NIST) announced an open competition for a new SHA-3 function to replace the older SHA-1 and SHA-2 after 2012?

You think they should wait until SHA-2 is broken to start looking for a replacement? Think about that for a second.

Quote

Is SHA-2 algorithm hard coded in the bitcoin protocol or not? Is it possible to upgraded it to SHA-3 after 2012?

It's possible, yes, but it's going to be a mess and require lots of cooperation.

becoin

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Bitcoin mining process consists of repeatedly increasing "nonce":

Quote

payload =
nonce = 1
hash = SHA2( SHA2( payload + nonce ) )

It merely tries to find the right number.

If SHA-2 is so secure then why have National Institute of Standards and Technology (NIST) announced an open competition for a new SHA-3 function to replace the older SHA-1 and SHA-2 after 2012?

http://en.wikipedia.org/wiki/NIST_hash_function_competition

Is SHA-2 algorithm hard coded in the bitcoin protocol or not? Is it possible to upgraded it to SHA-3 after 2012?

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