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Bitcoin’s race to outrun the quantum computer

decrypt.co

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Re: Bitcoin’s race to outrun the quantum computer

#11

Post by DennisP »

RandomBacon wrote: post #10
lixtra wrote: post #5

> Take the Bitcoin blockchain: an unencrypted public key is sent along with every bitcoin transaction, and left unencrypted during the time it takes for the network to confirm the block, around ten minutes. My understanding is that it remains unencrypted forever. That’s why it is a public key. As long as the coins are not moved to another account that public key stays a valuable target. Edit: As DennisP pointed out m…

So then if Satoshi destroyed the private keys instead holding on to them just in case for an event like this, it's possible that someone might take the million or so BTC just sitting around? Depending on how easy it is, all those addresses that were abandoned containing 50 BTC are also up for grabs. Would a coin without public addresses be better suited against such future?

Not if Satoshi's coins have never moved. A bitcoin address is a hash of a public key. The public key isn't revealed until the first time funds are transferred out of that address.

Re: Bitcoin’s race to outrun the quantum computer

#12

Post by DennisP »

ddtaylor wrote: post #9

It's worth mentioning that Bitcoin addresses aren't exposed on the blockchain as public keys, but hashes of the public keys. If you want to steal the coins you'll need to turn ripemd160(sha256(sha256(publicKey))) into a private key. Good luck.

Yes, but the public key is exposed when you send from that address. If a quantum computer is quick enough, it could get your private key and issue its own transaction, racing you to get into a block.

Re: Bitcoin’s race to outrun the quantum computer

#13

Post by Causality1 »

krastanov wrote: post #4

Just to be clear, this has barely anything to do with any crypto-currency organization. It is a really regrettable framing for an event that should be of great interest to anyone dealing with cryptography, not just the fairly restricted group of crypto-currentcy enthusiasts. If scalable quantum computers can be built (which seems probable, as we are progressing fast in the number of qubits we can keep together), then…

We seem to be getting better at using quantum computers for hard math. What I'm curious about is when we'll be able to use them for easy math. How many qubits do we need to run Doom Quantum?

Re: Bitcoin’s race to outrun the quantum computer

#14

Post by RandomBacon »

DennisP wrote: post #11
RandomBacon wrote: post #10

Earlier quoted context omitted.

So then if Satoshi destroyed the private keys instead holding on to them just in case for an event like this, it's possible that someone might take the million or so BTC just sitting around? Depending on how easy it is, all those addresses that were abandoned containing 50 BTC are also up for grabs. Would a coin without public addresses be better suited against such future?

Not if Satoshi's coins have never moved. A bitcoin address is a hash of a public key. The public key isn't revealed until the first time funds are transferred out of that address.

Okay, thanks!

Re: Bitcoin’s race to outrun the quantum computer

#15

Post by [deleted] »

DennisP wrote: post #11
RandomBacon wrote: post #10

Earlier quoted context omitted.

So then if Satoshi destroyed the private keys instead holding on to them just in case for an event like this, it's possible that someone might take the million or so BTC just sitting around? Depending on how easy it is, all those addresses that were abandoned containing 50 BTC are also up for grabs. Would a coin without public addresses be better suited against such future?

Not if Satoshi's coins have never moved. A bitcoin address is a hash of a public key. The public key isn't revealed until the first time funds are transferred out of that address.

[deleted]

Re: Bitcoin’s race to outrun the quantum computer

#16

Post by ridewinter »

krastanov wrote: post #4

Just to be clear, this has barely anything to do with any crypto-currency organization. It is a really regrettable framing for an event that should be of great interest to anyone dealing with cryptography, not just the fairly restricted group of crypto-currentcy enthusiasts. If scalable quantum computers can be built (which seems probable, as we are progressing fast in the number of qubits we can keep together), then…

The only truly safe encryption is quantum encryption. Any classical encryption algorithm should be breakable with quantum computers, even if we haven’t figured it out yet like with Shor’s.

Re: Bitcoin’s race to outrun the quantum computer

#18

Post by zazagura »

ridewinter wrote: post #16
krastanov wrote: post #4

Just to be clear, this has barely anything to do with any crypto-currency organization. It is a really regrettable framing for an event that should be of great interest to anyone dealing with cryptography, not just the fairly restricted group of crypto-currentcy enthusiasts. If scalable quantum computers can be built (which seems probable, as we are progressing fast in the number of qubits we can keep together), then…

The only truly safe encryption is quantum encryption. Any classical encryption algorithm should be breakable with quantum computers, even if we haven’t figured it out yet like with Shor’s.

Citation needed? Symmetric encryption algorithms like AES (with at least 256 bit key) are considered safe even against quantum computers, based on some reasonable math/qm assumptions.

Re: Bitcoin’s race to outrun the quantum computer

#19

Post by tialaramex »

krastanov wrote: post #4

Just to be clear, this has barely anything to do with any crypto-currency organization. It is a really regrettable framing for an event that should be of great interest to anyone dealing with cryptography, not just the fairly restricted group of crypto-currentcy enthusiasts. If scalable quantum computers can be built (which seems probable, as we are progressing fast in the number of qubits we can keep together), then…

> which seems probable, as we are progressing fast in the number of qubits we can keep together

Are we? Every so often I check back to see how well they're doing with actually running Shor's algorithm. In 2012 they managed to find that 21 = 3 x 7. And today... 21 = 3 x 7. That doesn't sound like progressing fast.

Quantum annealing is doing well for itself, but it isn't any sort of threat to encryption.

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