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Will quantum computing destroy blockchain and classical encryption algorithms as we know? So there will be a need for quantum blockchain and quantum encryption.

_Microft 4y ago
Post-quantum cryptography is a thing: https://en.wikipedia.org/wiki/Post-quantum_cryptography https://en.wikipedia.org/wiki/Post-quantum_cryptography
- fio_ini 4y ago
  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.
  - eimrine 4y ago
    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.
- DennisP 4y ago
  I'm wondering whether it avoids this new type of problem that QCs should be able to solve.
  - gxiv 4y ago
    Going by their description of the problem, it looks like it's distinct from how all the mainstream post quantum algos (LWE, NTRU, SIDH, etc) work. Edit: I've finished the article lol. Now I'm not so certain that this is 100% distinct from something like LWE.
- jl2718 4y ago
  Until it’s not. Nobody has proven any of these schemes to be secure against quantum attack. Post-quantum (today) just means that nobody has proven that the problem is equivalent to a problem that quantum computing can solve efficiently. This article is about LWE being proven breakable. Others will follow. The security of these schemes rests mostly upon the lack of researchers that understand them and quantum computing well enough to approach an equivalence class proof. Example: elliptic curve isogenies.
atwood22 4y ago
Classical asymmetric encryption algorithms like RSA and ECDSA (which Bitcoin uses) can be easily broken by a quantum computer. Brute-forcing symmetric algorithms like AES gets a speed up on a quantum computer, but not enough to consider the algorithms broken.
- astrange 4y ago
  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.
  - atwood22 4y ago
    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 https://bitcoin.stackexchange.com/a/102667
    - astrange 4y ago
      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.
      - atwood22 4y ago
        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.
- birdyrooster 4y ago
  Oh cool, can you tell me who has successfully and easily achieved this result?
t_mann 4y ago
> Will quantum computing destroy blockchain and classical encryption algorithms as we know? Short answer: the currently popular ones? Yes. All that we know? Probably not. See eg: https://ieeexplore.ieee.org/document/8967098 https://ieeexplore.ieee.org/document/8967098
spywaregorilla 4y ago
I'm surprised there aren't quantum blockchains already.
- q-big 4y ago
  > I'm surprised there aren't quantum blockchains already. There are: > https://www.quantumblockchains.io/ https://www.quantumblockchains.io/ > https://quantumblockchaintechnologies.co.uk/ https://quantumblockchaintechnologies.co.uk/ :-)
  - spywaregorilla 4y ago
    Oh sweet. Looks like quantum PoS is just .5 + .5i months out
    - andreareina 4y ago
      I think you're missing a couple of sqrt()s ;)

_Microft 4y ago

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

fio_ini 4y ago
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.
- eimrine 4y ago
  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.
DennisP 4y ago
I'm wondering whether it avoids this new type of problem that QCs should be able to solve.
- gxiv 4y ago
  Going by their description of the problem, it looks like it's distinct from how all the mainstream post quantum algos (LWE, NTRU, SIDH, etc) work. Edit: I've finished the article lol. Now I'm not so certain that this is 100% distinct from something like LWE.
jl2718 4y ago
Until it’s not. Nobody has proven any of these schemes to be secure against quantum attack. Post-quantum (today) just means that nobody has proven that the problem is equivalent to a problem that quantum computing can solve efficiently. This article is about LWE being proven breakable. Others will follow. The security of these schemes rests mostly upon the lack of researchers that understand them and quantum computing well enough to approach an equivalence class proof. Example: elliptic curve isogenies.

atwood22 4y ago

Classical asymmetric encryption algorithms like RSA and ECDSA (which Bitcoin uses) can be easily broken by a quantum computer. Brute-forcing symmetric algorithms like AES gets a speed up on a quantum computer, but not enough to consider the algorithms broken.

astrange 4y ago
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.
- atwood22 4y ago
  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 https://bitcoin.stackexchange.com/a/102667
  - astrange 4y ago
    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.
    - atwood22 4y ago
      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.
birdyrooster 4y ago
Oh cool, can you tell me who has successfully and easily achieved this result?

t_mann 4y ago

> Will quantum computing destroy blockchain and classical encryption algorithms as we know? Short answer: the currently popular ones? Yes. All that we know? Probably not. See eg: https://ieeexplore.ieee.org/document/8967098 https://ieeexplore.ieee.org/document/8967098

spywaregorilla 4y ago

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

q-big 4y ago
> I'm surprised there aren't quantum blockchains already. There are: > https://www.quantumblockchains.io/ https://www.quantumblockchains.io/ > https://quantumblockchaintechnologies.co.uk/ https://quantumblockchaintechnologies.co.uk/ :-)
- spywaregorilla 4y ago
  Oh sweet. Looks like quantum PoS is just .5 + .5i months out
  - andreareina 4y ago
    I think you're missing a couple of sqrt()s ;)