Vitalik Buterin says new “fast confirmation rules” for Ethereum could provide users with a clear guarantee that a block will not be reverted in a single slot, or after about 12 seconds. This is a change that will significantly reduce one of the network’s biggest real-world frictions for exchanges, bridges, and layer 2 systems.
This proposal, publicly outlined by Ethereum Foundation researcher Julian Ma and endorsed by Buterin on In Buterin’s words, this mechanism “provides a solid guarantee that Ethereum will not revert after one slot (12 seconds). The security assumptions are (i) absolute majority honesty, and (ii) network latency is less than ~3 seconds. So it’s one order of magnitude lower than economic finality, but very robust for many use cases.”
New Ethereum Rules for Faster Confirmations
That distinction is important. Ethereum finality remains the chain’s strongest payment guarantee, but it comes with much longer latency. Ma said the Fast Confirmation Rule (FCR) reduces deposit times from the Ethereum mainnet to L2 and centralized exchanges to about 13 seconds. He described this as “an 80-98% reduction across most L2s and exchanges.”
The immediate result for users is speed. For infrastructure providers, the bigger issue is efficiency. Ma argued that slow mainnet confirmations have forced exchanges, bridges, and rollups to operate around delays and uncertainty, especially when processing deposits or synchronizing market activity across chains. “Connecting funds from Ethereum to L2 and centralized exchanges is slow, with users waiting several minutes when using standard bridges,” he wrote. “The new Fast Confirmation Rule (FCR) solves this problem. It reduces the time it takes to deposit or exchange from Ethereum L1 to L2 to approximately 13 seconds.”
He added that the rules are expected to become “the new industry standard for L2 and exchanges” and could begin rolling out in the coming months without a hard fork. This is a notable design choice. Rather than introducing consensus changes that require network-wide coordination, FCR can be enabled as clients implement it, and once support is enabled, nodes can automatically enforce rules.
Ma’s explanation frames FCR as a middle ground between today’s heuristics and Ethereum’s formal finality. Most exchanges, L2s, and solvers do not currently wait for finality. Instead, they rely on block depth rules, or “k-deep,” which wait until a transaction is buried beneath enough subsequent blocks. FCR takes a different route. That is, it computes proof rather than blocking. According to Ma, it is architecturally faster and provides a provable security model that k-deep lacks.
The trade-off is obvious. Blocks that are confirmed quickly are not confirmed and guarantees depend on stricter assumptions than finality. FCR actually assumes a synchronous network, which means proofs will arrive in about 8 seconds, and it assumes that no attacker controls more than 25% of the staked ETH. In contrast, finality is designed to maintain asynchrony and an adversarial threshold of up to 33%.
Nonetheless, Ma argued, the system deteriorates gracefully as conditions worsen. “If the network is slow, FCR has a built-in fallback mode: instead of quickly verifying blocks in 13 seconds, it may take slightly longer,” he wrote. “As soon as enough proofs are delivered, blocks are quickly confirmed. In the worst case, FCR reverts to its final state.”
That replacement is the heart of the stadium. The mechanism does not pretend that the risk of reconfiguration disappears. This is claimed to dramatically reduce latency while maintaining deterministic guarantees when the assumption holds. Ma also emphasized that if these assumptions hold, quickly confirmed blocks “will definitely be finalized.”
At press time, ETH was trading at $2,319.
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