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Quantum algorithms conquer a new kind of problem

quantamagazine.org

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Re: Quantum algorithms conquer a new kind of problem

#31

Post by astrange »

atwood22 wrote: post #28
astrange wrote: post #27

Earlier quoted context omitted.

Bitcoin doesn't use them in a way that'd let you completely break it; the asymmetric keys aren't broadcast until someone does a new transaction with them, so you can't fake one for a wallet you've never seen the public key to.

How is the transaction signature verified without the public key? This link seems to indicate spender public keys are inside of the transaction: https://bitcoin.stackexchange.com/a/102667

Ah, I had the details wrong. If there’s a signed transaction from a wallet, then you have the compressed public key and it’s not quantum safe.

But if the funds are sent to a new wallet address and there’s no transactions signed by that wallet yet, it can’t be forged without also reversing the hash that created the address.

Re: Quantum algorithms conquer a new kind of problem

#32

Post by atwood22 »

astrange wrote: post #31
atwood22 wrote: post #28

Earlier quoted context omitted.

How is the transaction signature verified without the public key? This link seems to indicate spender public keys are inside of the transaction: https://bitcoin.stackexchange.com/a/102667

Ah, I had the details wrong. If there’s a signed transaction from a wallet, then you have the compressed public key and it’s not quantum safe. But if the funds are sent to a new wallet address and there’s no transactions signed by that wallet yet, it can’t be forged without also reversing the hash that created the address.

Yes, it was a good idea to do that. I didn't realize that addresses were essentially a hash of the public key, but it makes sense.

Re: Quantum algorithms conquer a new kind of problem

#33

Post by spywaregorilla »

q-big wrote: post #29
spywaregorilla wrote: post #26

Earlier quoted context omitted.

I'm surprised there aren't quantum blockchains already.

> I'm surprised there aren't quantum blockchains already. There are: > https://www.quantumblockchains.io/ > https://quantumblockchaintechnologies.co.uk/ :-)

Oh sweet. Looks like quantum PoS is just .5 + .5i months out

Re: Quantum algorithms conquer a new kind of problem

#34

Post by andreareina »

spywaregorilla wrote: post #33
q-big wrote: post #29

Earlier quoted context omitted.

> I'm surprised there aren't quantum blockchains already. There are: > https://www.quantumblockchains.io/ > https://quantumblockchaintechnologies.co.uk/ :-)

Oh sweet. Looks like quantum PoS is just .5 + .5i months out

I think you're missing a couple of sqrt()s ;)

Re: Quantum algorithms conquer a new kind of problem

#35

Post by eimrine »

fio_ini wrote: post #11
_Microft wrote: post #8

Earlier quoted context omitted.

Post-quantum cryptography is a thing: https://en.wikipedia.org/wiki/Post-quantum_cryptography

wow this is pretty interesting stuff thanks for the link. I'm not sure why I get such a negative response to my question since I'm seriously asking and not sure I should be concerned if this is like a alan turing enigma type of situation we're dealing with.

IMO this is kind of P!=NP situation. While this statement is true, blockchain and classic cryptography keep existing. Maybe some minor improvements, like new hash algos or more significant bits, will be needed soon.
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