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Security issues for BTC.
From here: https://www2.deloitte.com/nl/nl/pag...tum-computers-and-the-bitcoin-blockchain.html
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From here: https://www2.deloitte.com/nl/nl/pag...tum-computers-and-the-bitcoin-blockchain.html
Since Google announced that it achieved quantum supremacy there has been an increasing number of articles on the web predicting the demise of currently used cryptography in general, and Bitcoin in particular. The goal of this article is to present a balanced view regarding the risks that quantum computers pose to Bitcoin.
All known (classical) algorithms to derive the private key from the public key require an astronomical amount of time to perform such a computation and are therefore not practical. However, in 1994, the mathematician Peter Shor published a quantum algorithm that can break the security assumption of the most common algorithms of asymmetric cryptography. This means that anyone with a sufficiently large quantum computer could use this algorithm to derive a private key from its corresponding public key, and thus, falsify any digital signature.
The prerequisite of being “quantum safe” is that the public key associated with this address is not public. But as we explained above, the moment you want to transfer coins from such a “safe” address, you also reveal the public key, making the address vulnerable. From that moment until your transaction is “mined”, an attacker who possesses a quantum computer gets a window of opportunity to steal your coins.
In such an attack, the adversary will first derive your private key from the public key and then initiate a competing transaction to their own address. They will try to get priority over the original transaction by offering a higher mining fee.
In the Bitcoin blockchain it currently takes about 10 minutes for transactions to be mined (unless the network is congested which has happened frequently in the past). As long as it takes a quantum computer longer to derive the private key of a specific public key then the network should be safe against a quantum attack. Current scientific estimations predict that a quantum computer will take about 8 hours to break an RSA key, and some specific calculations predict that a Bitcoin signature could be hacked within 30 minutes.
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