TLDR Tech / Crypto
How Ethereum Plans to Replace BLS with Post-Quantum Signatures
The Lean Ethereum team is working on replacing BLS signatures, which underpin consensus across Ethereum's ~1 million validators but are vulnerable to Shor's algorithm on quantum computers, with a hash-based scheme called LeanSig. LeanSig builds on XMSS and Merkle trees to give validators a stateful many-time signing structure that uses only hash functions rather than elliptic curve pairings, making it quantum-resistant by design. Aggregation of the resulting signatures (which can't be combined algebraically the way BLS can) is handled by a custom hash-based zkVM called leanVM, inspired by Cairo and formally verified using the Lean proof assistant.
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