ERC-7668, officially titled "Remove bloom filters," represents a significant evolution in Ethereum's data indexing strategy proposed by Vitalik Buterin in March 2024. This proposal addresses the growing inefficiencies of bloom filters in Ethereum's transaction receipt system by removing them entirely and encouraging applications to adopt ZK-SNARK-based provable log indexes for superior scalability and functionality.
Understanding Ethereum's Current Bloom Filter System
Currently, Ethereum uses bloom filters—probabilistic data structures stored in block headers—to enable quick searches for transaction logs and smart contract events. These 2048-bit filters allow applications to efficiently determine whether specific events might exist in a block without downloading complete transaction data. However, bloom filters have inherent limitations including false positives and increasing storage overhead as the network scales.
The proposal recognizes that modern applications requiring cross-chain transaction indexing face significant challenges with the current bloom filter approach, particularly when building sophisticated query systems across multiple blockchain networks.
ZK-SNARK-Based Log Indexing Revolution
ERC-7668 proposes replacing bloom filters with decentralized protocols that create provable log indexes using ZK-SNARKs and incrementally verifiable computation. This approach offers several advantages over traditional bloom filters: enhanced accuracy through cryptographic proofs, improved scalability for complex queries, and elimination of false positives that currently complicate application development.
For stablecoin infrastructure providers building cross-chain solutions, this transition enables more reliable event tracking and verification across different networks without the probabilistic uncertainty inherent in bloom filters.
Implementation Impact and Timeline
The proposal requires that bloom filters in execution blocks become empty, effectively deprecating this functionality while maintaining backward compatibility. Applications that depend on log querying functionality will need to migrate to advanced bridging protocols that implement ZK-SNARK-based indexing systems.
This change aligns with Ethereum's broader transition toward zero-knowledge proof systems, supporting the network's scalability goals while providing developers with more powerful tools for building next-generation decentralized applications that require precise, verifiable event tracking across the expanding multi-chain ecosystem.