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April 10, 2016, 02:05:24 AM |
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This has already been discussed for a while and many many times here. I'll sum up why we don't have to worry too much and how quantum computers won't be the end of the world for Bitcoin.
First of all, there are no known quantum computer algorithms which can make hashing sha256 faster or for finding preimages of sha256 hashes or collisions. Even so, Bitcoin is fairly well protected as the difficulty would just adjust and the double sha256 hash puts an extra step in there which would make any attack more difficult.
Secondly, the only way that quantum computers would mess with Bitcoin is by finding the private key to a public key. However, you can protect against this by not reusing addresses. Since the public key is not revealed until a transaction is spent, any attacker would not be able to find the private key to a public key that is not known until it is revealed in a transaction. By that point, the Bitcoin is spent, and although they could attempt to double spend it, I don't think quantum computers bring that speed down to less than ten minutes. The only issue is if people don't include enough fees and the transaction takes a while to become confirmed. Then there could possibly be possibility of the Bitcoin being stolen.
Lastly, I think the developers would be able to come to consensus on a need to hard fork Bitcoin to quantum resistant algorithms should there be need. In fact, they probably will deploy quantum resistant cryptography before quantum computers become advanced and cheap enough to be used by attackers for attacking Bitcoin. Quantum computers will take several years to become commonplace and by that point, I think everyone could come to consensus to upgrade.
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