Celo All-Core Dev Call #3


The Celo All-Core Dev Call #3 took place with a good turnout of participants. The agenda for the call included discussions on the upcoming hard fork, specifically the last call for Donut CIPs (Celo Improvement Proposals), and a proposal for Bison Trails outlined in CIP 29. The participants were informed that CIP 29 aims to introduce a grace period for validator uptime calculation, allowing additional blocks of downtime without penalties. The proposed solution involves adjusting the rewards calculation within on-chain smart contracts. The Celo Labs team expressed their inclination towards accepting CIP 29 and incorporating it into the next major contract upgrade on the mainnet.

CIP 29: Grace Period for Validator Uptime Calculation

CIP 29 proposes a change to the validator uptime calculation to accommodate routine maintenance without imposing penalties. The Celo Labs team supports this change and plans to bundle it into the next significant contracts upgrade scheduled for early next year. The participants were invited to ask questions or raise concerns regarding CIP 29, either during the call or in the CIP repository in the following weeks.

Donut Update

The other significant item on the agenda was the Donut update. A list of CIPs for the Donut hard fork was compiled and tracked in a public GitHub project. The Celo community was assured that any CIP included in this list would be implemented and released during the Donut hard fork, planned for March. Updates named “Elf Horse” and “Baklava” were scheduled for early to mid-February. The call facilitator offered to provide a brief summary of each CIP in number order and encouraged attendees to follow the progress on the public dashboard.

CIP 20: Extensible Hash Functions

CIP 20 introduces additional hash functions, such as SHA-3, CAT, SHAKE, and Blake2s, to the EVM (Ethereum Virtual Machine). This expansion allows for more cryptographic protocol options currently missing in Ethereum and the EVM. The proposed update supports the Plumo requirements and facilitates slashing on Plumo proofs.

CIP 22: Epoch Snark Data

CIP 22, developed by the Celo Labs crypto team, aims to support ultralight client verification through minor changes to commitments in the block header. This modification is not expected to be controversial.

CIP 21: Governable Look Back Window

CIP 21 complements CIP 29 by addressing the same problem in a slightly different way. It proposes adding a governance parameter for the look back window, which currently has a fixed duration of one minute. The goal is to make this duration adjustable through community voting. Since this change involves modifying blockchain parameters, it requires a hard fork.

CIP 25: 25519 Precompile

CIP 25, implemented by Chorus under the Celo Foundation’s grant, introduces the 25519 precompile, based on an old EIP (Ethereum Improvement Proposal) 665. This update expands the range of cryptographic protocols that can be executed on the Celo blockchain. 25519 is widely used by other blockchain networks, such as Near, Solana, and Cosmos, as well as in cryptographic applications outside of the blockchain space.

CIP 26: Validator Pub Keys Lookup

CIP 26 involves a small code change to implement a precompile that enables the lookup of validator public keys from previous epochs. This change aligns with Plumo requirements and is expected to be non-controversial.

CIP 28: Split Ether Base

CIP 28 fulfills a request from validators to allow the splitting of rewards for validation and transaction fees into separate addresses. The primary goal is to simplify validator operations without significant impact on operating nodes.

CIPs 30 and 31: BLS-related Precompiles

CIPs 30 and 31 introduce a set of BLS-related precompiles that support 12,381 and 12,377 cryptographic protocols. These updates expand the range of cryptographic algorithms available on the Celo blockchain, accommodating the increasing popularity of these algorithms in the blockchain space. The precompiles enable the verification of Celo validator signatures within the Celo EVM.


The Celo All-Core Dev Call #3 covered important topics related to the upcoming hard fork and the Donut update. The participants discussed and reviewed several CIPs, addressing issues such as validator uptime calculation, hash functions, epoch snark data, governable look back window, 25519 precompile, validator pub keys lookup, split ether base, and BLS-related precompiles. The Celo Labs team expressed their confidence in the proposed changes, with plans to implement them unless any significant concerns or issues are raised during the review period. The next major contract upgrade is expected to take place in early next year, and the Donut hard fork is scheduled for March. The call concluded with participants being encouraged to review the CIPs and provide feedback or raise any objections to ensure a smooth transition during the upcoming updates.