Ethereum's post quantum era
After Google unveiled Willow, their quantum chip. There is a buzz around the web3 ecosystem about what would be the next paradigm shift when quantum computers become mainstream as quantum computers can crack the current hashing algorithms used by ethereum and other general purpose blockchains.
Vitalik already wrote an article earlier that year on How to hard fork to save most users' funds in a quantum emergency, which shows that he already had an idea about this situation could occur in the near future.
So which post quantum signature should we use?
Former Ethereum Foundation cryptographer Zhenfei Zhang, has already written about the # NIST Post-Quantum-Cryptography Standardization Process and What it means for Ethereum which talks about four possible candidates for quantum safe cryptography algorithms. The algorithms are Kyber, Dilithium, Falcon and SPHINCS+. Three of which are lattice based digital signature scheme and the last one is hash based digital signature scheme.
A new question arises : What are lattice based digital signature algorithms? A lattice in mathematics is a regular, repeating arrangement of points in $n$ dimensional space. A lattice, in 2D might look like a grid of points that extends infinitely in all directions. Interesting characteristics about lattices are we can represent the same form of lattice using different vectors. Post-quantum cryptography: Lattice-based cryptography article by Redhat discusses about lattices and the algorithms in depth.
From the 3 lattice based algorithms that are considered in the NIST list, Falcon comes out to be the most promising due to it's efficiency and small size.
There are three suggested ways in which PQ signatures can be implemented
Account abstraction way
Hard fork way
Hybrid (AA + hard fork)
The three different methods have their own pros and cons, details of which is being discussed in this post So you wanna Post-Quantum Ethereum transaction signature
Conclusion
With the advancement of quantum computers, this issue needs to be addressed urgently because ethereum's tx signatures are vulnerable to Shor's Algorithm. Everything is still in a discussion phase to ensure whatever choices are being made doesn't affect the users' funds and the blockchain majorly. But with the swift nature of development it is only a matter of time until we have a clear picture about the updates in Ethereum in PQ era.