Switching Over To Savanna Consensus Algorithm

Switching over to the Savanna Consensus Algorithm is a multi-step process.

Overview of Upgrade Process

There are four steps

Upgrade Antelope Software, Spring and EOS System Contracts
Block Producers generate and register finality keys
- First activate protocol feature BLS_PRIMITIVES2
- See section below on Generate and Registering Finalizer Keys
Activate required protocol features
- Activate SAVANNA protocol feature
eosio user calls switchtosvnn action

Antelope Software Requirements

Switching to Savanna will required the latest version of Spring Software and the EOS System Contracts.

Note: CDT v4.1.0 is needed to compile the latest EOS System Contracts. This version of CDT contains both the needed host functions, and cryptography support needed to support managing finalizer keys.

Protocol Features Dependencies

The reference for protocol features with their corresponding hashes may be found in bios-boot-tutorial. Switching to the SAVANNA consensus algorithm, requires the activation of the SAVANNA protocol feature. This feature depends all protocol features available in Spring v1.0.0 being in the active_schedule. This full list of protocol features in Spring v1.0.0 is listed below.

DISABLE_DEFERRED_TRXS_STAGE_1
DISABLE_DEFERRED_TRXS_STAGE_2
WTMSIG_BLOCK_SIGNATURES
BLS_PRIMITIVES2
DISALLOW_EMPTY_PRODUCER_SCHEDULE
ACTION_RETURN_VALUE
ONLY_LINK_TO_EXISTING_PERMISSION
FORWARD_SETCODE
GET_BLOCK_NUM
REPLACE_DEFERRED
NO_DUPLICATE_DEFERRED_ID
RAM_RESTRICTIONS
WEBAUTHN_KEY
BLOCKCHAIN_PARAMETERS
CRYPTO_PRIMITIVES
ONLY_BILL_FIRST_AUTHORIZER
RESTRICT_ACTION_TO_SELF
GET_CODE_HASH
CONFIGURABLE_WASM_LIMITS2
FIX_LINKAUTH_RESTRICTION
GET_SENDER
SAVANNA

Generate and Registering Finalizer Keys

The Savanna Consensus algorithm utilized by Spring v1 separates the roles of publishing blocks from signing and finalizing blocks. Finalizer Keys are needed to sign and finalize blocks. In Spring v1, all block producers are expected to be finalizers. There are three steps to creating finalizer keys

generate your key(s) using spring-utils
add signature-provider to configuration with the generated key(s)
restart nodeos with the new signature-provider config
register a single key on chain with the regfinkey action

Additional information on Finalizer Keys may be found in Guide to Managing Finalizer Keys and Introduction to Finalizers and Voting.

Confirmation of Consensus Algorithm

The action switchtosvnn, initiates the change to the Savanna Consensus Algorithm, and must be called by the owner of the system contracts. On EOS Mainnet this would be the eosio user. This is event is called only once per chain.