What is Solana's defense against quantum computers?

Question

I apologize in advance for being a bit catastrophic, but how feasible is it for the Solana blockchain to defend against Shor's algorithm attacks if, in the distant (or perhaps not-so-distant) future, quantum computers gain enough logical qubits to reveal private keys from public keys in elliptic curve signatures? As far as I know, public keys in Solana are not hidden behind any hash, and each address is essentially a public key.

Assuming hash functions like SHA256 remain unaffected, and thus the logic of programs and PDAs would not be compromised.

I'm not interested in speculating whether such quantum computers will eventually exist, but rather, what would be the potential process for upgrading the entire blockchain in response, and what would happen to coins on addresses that do not migrate to a new type of signature mechanism?

Recently, I came across an interesting tweet from Jameson Lopp, where he quoted Scott Aaronson, suggesting that this era might be approaching faster than we think. Here's the tweet: https://x.com/lopp/status/1845806381091229955.

Answer 1

This question comes up every once in awhile. The general upgrade process would likely require:

• changing the signature generation and verification algorithm to something quantum-resistant
• defining a migration process from old accounts to new ones (ie. the account at address will now be owned by some other address) <-- this is the trickiest bit, since it requires migration from the old address to a new one protected by a new keypair. This needs to be done manually by all users. Otherwise, once the old private keys are breakable, and the funds haven't been migrated to new safe addresses, it may be possible to steal those funds.