Announcing Protocol 22

A new protocol is on the horizon. Protocol 22, which introduces constructors for Soroban and support of BLS12-381 encryption, will hit Testnet November 12, and go up for Mainnet validator vote December 5. Check out the Protocol 22 Upgrade Guide to make sure you've installed compatible Stellar-related software before those upgrades.

Here's what's new in Protocol 22: The two new CAPs introduced in Protocol 22 are CAP-0058: Constructors for Soroban contracts and CAP-0059: Host functions for BLS12-381. Let’s delve into these a bit more so we know what to expect with Protocol 22.

CAP-0058 introduces constructors for Stellar smart contracts, simplifying the initialization process. A constructor is a special function that runs automatically when a contract is deployed, setting up the contract's initial state, such as assigning values to variables or configuring permissions. This ensures the contract starts in a valid and usable state with all necessary data. Currently, Stellar developers must manually include additional logic or checks to handle initialization, but with constructors, this process becomes automatic upon deployment.

Implementing constructors makes contracts more efficient by reducing their size, lowering CPU usage during execution, and minimizing storage requirements. It also enhances security by making it harder for developers to unintentionally expose their contracts to front-running (an attack where someone uses their knowledge of a pending transaction to gain an unfair advantage) during initialization.

Constructors are supported in other smart contract frameworks and languages (like Solidity in Ethereum), so this CAP helps to align Stellar with other networks and eases friction in developer onboarding.

Read more technical details about CAP-0058: Constructors for Soroban contracts on GitHub here.

BLS12-381 is a widely adopted type of elliptic curve used in cryptography, known for its efficiency and strong 128-bit security. This curve enables pairing-based cryptography, which enables advanced cryptographic operations like zk-SNARKs (Zero-Knowledge Succinct Non-Interactive Arguments of Knowledge). zk-SNARKs allow a prover to demonstrate to a verifier that they possess certain information or that a statement is true without revealing the underlying information.

A key use case for zk-SNARKs is anonymous login, such as zkLogin or zkEmail, where users can authenticate using real-world Web2 identities (like their Gmail address) to sign a transaction, where the transaction is verified on-chain without exposing the user’s actual email address. This capability supports a more seamless onboarding experience into Web3 for Web2 users.

Operations involving the BLS12-381 elliptic curve are computationally intensive, making it difficult to implement them directly into a smart contract. To address this, these operations are implemented in the Soroban host environment, allowing smart contracts to leverage them without having to handle the complex computations themselves.

Learn more about BLS12-381 on Stellar, including a deep dive into the 11 new host functions on GitHub here.

The Testnet upgrade to Protocol 22 is scheduled for November 12, 2024, with the Mainnet vote following on December 5, 2024. If you're building on the Stellar network and want to ensure you're prepared for the upgrade, check out the Protocol 22 Upgrade Guide. It provides helpful guidance on upgrading to the latest versions of Stellar software, including the SDKs, RPC, Horizon, and Stellar Core.

Be sure to stay current on any Protocol 22-related announcements in the Stellar Developer Discord, where the ecosystem coordinates and shares information about the upgrade.