Ethereum Hash Function Debate Heats Up as Flock Removes Circuit-Friendly Constraint
Ethereum's hash function debate has resurfaced as researchers compare SHA-2, SHA-3/Keccak, BLAKE2, BLAKE3, and a modified SHA-2 variant on security and speed.
The debate is no longer constrained by circuit-friendly designs like Poseidon, thanks to the emergence of Flock, a post-quantum proof system for binary circuits that handles hashing efficiently regardless of the algorithm chosen.
Hash functions are deeply embedded across Ethereum's architecture, with each candidate protecting against collision and preimage attacks differently. SHA-2 is fast but lacks a true random oracle due to its length-extension weakness, while SHA-3 offers a high security margin at the cost of slower performance.
BLAKE2 ranks among the fastest hash functions available, but its provably indifferentiable compression function comes with a thinner cryptanalysis record than SHA-2 or SHA-3. BLAKE3 pushes performance 40% further by reducing design rounds and altering internal block cipher operations, but strips away the indifferentiability proof.
The risk-minimizing ranking places SHA-3 first, followed by BLAKE2s and a modified SHA-2 variant, with BLAKE3 ranked lower due to its thinner track record of independent cryptanalysis. This framing highlights the trade-off between security scrutiny and performance, where the fastest option is not always the most scrutinized.