Staking protocol

Introduction

While Starknet is currently still centralized, it is gradually moving towards employing a staking protocol, handing over the responsibilities of producing, attesting, and proving blocks to validators. To facilitate this gradual implementation, the protocol’s architecture is modular, ensuring maximum flexibility and ease of upgrades. However, anyone holding STRK in their wallets can already stake their tokens and earn rewards based on their level of participation by following a few simple steps.

If you are only interested in learning how to stake on Starknet, feel free to skip straight to Procedures.
Additional resources

Roadmap

Naturally, handing over the responsibility for maintaining and securing Starknet to validators in one day is neither feasible nor desirable. Instead, the staking protocol is implemented in incremental phases, with each phase bringing additional requirements from validators until they fully maintain and secure the network. The protocol is currently in the first (on Mainnet) and second (on Sepolia) of four phases, illustrated in following figure:

The staking protocol is currently in its first phase on Mainnet and in its second phase on Sepolia.
staking roadmap

Protocol

The following sections describe the details of Starknet’s staking protocol. The parameters used in the protocol are summarized in the following table:

Parameter Mainnet Sepolia

Minimum stake for validators

20K STRK

1 STRK

Minting curve yearly inflation cap (\(C\))

1.6

1.6

Withdrawal security lockup

21 days

5 minutes

Epoch length (\(E\))

120

40

Attestation window (\(W\))

16

16

Number of epochs used for latency (\(k\))

3600

1200

Roles

Starknet’s staking protocol features two options for participation:

  • Staking directly as validators: Staking a minimum of 20,000 STRK and earning rewards by handling any responsibilities the protocol requires

  • Staking indirectly as delegators: Delegating STRKs to validators who allow delegation and sharing in their rewards without handling any of their responsibilities

    Validators can choose whether to allow delegation or not.

Addresses

To reduce exposure to threats and enhance security, multiple addresses for defined for both validators and delegators:

  • Validator addresses:

    • Staking address: Used for staking, adding stake, and unstaking. This address is only needed when entering or exiting the protocol and handles large amounts of STRK, and therefore is best kept by a cold wallet with minimal activity.

    • Rewards Address: Used for receiving rewards. This address is only needed when receiving rewards, and therefore is best kept by a cold wallet.

    • Operational Address: Used for operational purposes, such as block attestations (starting from the protocol’s second phase), block proposing (starting from the protocol’s third phase), etc. This address is used frequently and doesn’t handle large amounts of funds, and therefore is best kept by a hot wallet. Starting from the protocol’s second phase, however, hacking the operational address can lead to a lose of yield for the validator and its delegators.

  • Delegator addresses:

    • Staking address: Used for delegating stake, adding stake and unstaking. This address is only needed when entering or exiting the protocol and handles large amounts of STRK, and therefore is best kept by a cold wallet with minimal activity.

    • Rewards Address: Used for receiving rewards. This address is only needed when receiving rewards, and therefore is best kept by a cold wallet.

The protocol uses a hierarchical approach between the staking and rewards addresses, and both validators and delegator can also use their staking address whenever their rewards address is required.

Epochs

Starting from its second phase, the staking protocol introduces the notion of epochs (similarly to many other protocols). Epochs represent checkpoints where validators' stakes are set, such that changes made in epoch \(i\) are applied in epoch \(i+k\), where \(k\) is a new latency parameter. For example, the following figure illustrates a scenario where in epoch \(i\) validator \(A\) has 50K STRK staked and someone delegates an additional 10K STRK to them, and in epoch \(i+1\) someone undelegates 30K STRK from \(A\):

epochs example

Responsibilities

Running a full node

The staking protocol requires validators to run one of the following full node implementations:

Name Hardware requirements Integration guide

Juno

juno.nethermind.io/hardware-requirements

juno.nethermind.io/running-juno

Madara

docs.madara.build/hardware

github.com/madara-alliance/madara/README.md

Pathfinder

eqlabs.github.io/pathfinder/getting-started/hardware-requirements

eqlabs.github.io/pathfinder/getting-started/running-pathfinder

Block attestation

Starting from its second phase, the staking protocol requires validators to attest to blocks, by running one of the following software:

How does the block attestation mechanism work?

In each epoch, each validator is assigned a single block whose relative number within the epoch is defined as follows:

\[h(\text{staked amount},\text{epoch id},\text{validator address}) \mod (E-W)\]

where:

  • \(E\) is the number of blocks in an epoch, termed epoch length

  • \(W\) is the number of blocks applicable for attestation submittal, termed attestation window

During each epoch, validators have the opportunity to attest to their assigned block by submitting an attest transaction, which must be included within the attestation window. For example, if \(W = 20\) and \(N\) is the relative block number assigned to validator \(A\), then \(A\) must submit an attest transaction between the blocks whose relative number within the epoch are \(N+1\) and \(N+20\).

In the second phase of the protocol, each Validator is required to perform only one attestation per epoch.

The attest transaction includes the block hash of the attested block, ensuring validators actively use full nodes, as they need to continuously track block hashes. Additionally, the attestation is publicly verifiable, ensuring validators' reliability is publicly tested — a crucial prerequisite before handing them any core responsibilities.

Rewards

Rewards are distributed based on the amount staked and the commission policy constant \(CP\) set by the validator, with yearly reward percentages calculated using the following formulas:

  • For delegators:

    \[\text{stake_delegated} \cdot (1 - CP) \cdot \frac{M}{S}\]

  • For validators:

    \[\left(\text{self_stake} + \text{total_stake_delegated} \cdot CP\right) \cdot \frac{M}{S}\]

where \(M\) and \(S\) are defined by the Minting curve.

Starting from the second phase of the protocol, rewards are accumulated per epoch only for validators who performed their attestations in the epoch on an “all or nothing” basis — so validators that submitted a transaction during the epoch that proves they tracked the network will receive all the rewards for the epoch based on their staked amount, while validators that didn’t will get no rewards for the epoch’s entire duration. After performing the attestation, the rewards that go directly to the validator will accumulate in his account, and the rest will go to this validator’s pool. Stakers that enter the protocol on epoch \(i\) will start getting rewards only on epoch \(i+k\), and stakers that signal an intent to exit the protocol on epoch \(i\) will still get rewards until epoch \(i+k-1\).

Starting from the second phase of the protocol, when a delegator claims his rewards, all rewards they received from all epochs since the last time they claimed rewards will be accumulated. The complexity of this operation is \(O(\text{#delegator's balance changes since last claim})\) — and not \(O(\text{#epochs since last claim})\) — which is assumed to be small enough to fit in one transaction in any real-world-scenario. This mechanism replaces the global reward index that was used prior to the protocol’s second phase.

Minting curve

The minting curve balances participation and inflation by adjusting rewards based on the total STRK locked in the protocol, and is defined by the following formula:

\[M = \frac{C}{10} \times \sqrt{S}\]

where:

  • \(S\) is the staking rate as a percentage of the total token supply

  • \(M\) is the annual minting rate as a percentage of the total token supply

  • \(C\) is the maximum theoretical inflation percentage, set to 1.6%

Latencies

The following latencies are set in place:

  • To disincentivise sudden large withdrawals that could destabilize the network, funds are subject to a 21-day lockup after signaling an unstake intent, during which no rewards are earned and funds cannot be withdrawn.

  • Starting from the second phase of the protocol, to prevent delegator from switching too quickly between validators while still promoting a competitive delegation market, a switch intent that is signaled on epoch \(i\) takes effect only on epoch \(i+1\).

Commissions

Starting from its second phase, the staking protocol allows validators to increase their commission. To avoid an unexpected increase in commissions, validators must commit to a certain maximum commission \(M\) and the last date (in epochs) that this commitment is relevant for. Until this date arrives, validators cannot increase their commission beyond \(M\), but can freely change their commission in the range \([0,M]\).

Architecture

The implementation of Starknet’s staking protocol is divided into several contracts, summarized in the following figure:

staking architecture

This modular architecture allows for targeted upgrades and improvements without affecting the entire system. Access control mechanisms are also in place to ensure that only authorized parties can make critical changes, further enhancing the security of the staking process. The following table details the key components of the architecture:

Contract Description

Staking

The staking contract is the core of the staking system, managing the entire lifecycle of staking, from initial staking to claiming rewards and unstaking.

The staking contract also stores the StakerInfo data structure, which holds detailed information about each validator, including their staked amount, unclaimed rewards, delegation details, and operational parameters, and helps to ensure that validators' information is accurately tracked and updated.

Delegation pooling

All delegation interactions, such as entering or exiting a pool, are enabled through the delegation pooling contract, which tracks each delegator’s contribution, calculates their rewards, and manages the delegation lifecycle.

The delegation pooling contract also stores the PoolMemberInfo data structure, which holds information about each delegator’s contributions, rewards, and status within the pool, and helps manage and calculate the delegation and reward distribution processes for pool members.

Reward Supplier

The reward supplier contract is responsible for calculating and supplying the staking rewards based on the minting curve, ensuring the rewards are distributed fairly and in accordance with the protocol’s economic parameters.

Minting Curve

The minting curve contract defines the economic model that governs reward distribution, ensuring that the network’s inflation is managed while incentivizing participation of stakers.

Attestation

The attestation contract manages the tracking of successful validator attestations, by verifying whether the validator has correctly attested to their assigned block within a designated attestation window.

Procedures

The following tables detail the procedures enabled by the staking protocol for both validators and delegators, along with the instructions to perform them.

To invoke onchain contracts, use Starknet Foundry’s sncast, Starkli, or a block explorer. To get the onchain addresses of the staking and STRK contracts, see Important addresses.

Staking as validators

Procedure Instructions Notes

Staking

Invoke the staking contract’s stake function

  • You should make sure you are running a full node (on Mainnet) and attesting to blocks (on Sepolia) before staking

  • You must first approve the transfer of the amount of STRK tokens to be staked to the staking contract by invoking the STRK contract’s approve function

  • operational_address should have sufficient funds to pay for attestation transactions

  • amount should be equal or greater than the minimum stake for validators and denominated in FRI (i.e., 1*1018 = 1 STRK)

  • commission should be entered as a percentage with precision, where 10000 represents 100% (e.g., to set a 5% commission, you enter 500)

Claiming rewards

Invoke the staking contract’s claim_rewards function

Increasing stake

Invoke the staking contract’s increase_stake function

  • amount should be denominated in FRI (i.e., 1*1018 = 1 STRK)

  • You must first approve the transfer of STRK tokens to the staking contract by invoking the STRK contract’s approve function

Updating commission

Invoke the staking contract’s update_commission function

  • commission should be entered as a percentage with precision, where 10000 represents 100% (e.g., to set a 5% commission, you enter 500)

  • In the first phase of the staking protocol (currently on Mainnet), commissions can only be decreased

  • In the second phase of the staking protocol (currently on Sepolia), commissions can be increased only after committing to a maximum commission using set_commission_commitment

Changing reward address

Invoke the staking contract’s change_reward_address function

Changing operational address

Invoke the staking contract’s declare_operational_address and change_operational_address functions

Opening delegation

Invoke the staking contract’s set_open_for_delegation function

Opening delegation is necessary only if pool_enabled was set to false when invoking the staking contract’s stake function

Unstaking

Invoke the staking contract’s unstake_intent and unstake_action functions

  • Once an unstake intent is signaled:

    • Funds are removed from the total balance and are no longer part of the staking protocol

    • The same staking address cannot be used to "restake" (i.e., unstake_action is irreversible)

  • unstake_action should be invoked only after the appropriate waiting period has ended

Staking as delegators

The following procedures are only intended for developers who are either interested (for whatever reason) in staking as delegators without using a staking dashboard, or are building one.
Procedure Instructions Notes

Entering a delegation pool

Invoke the delegation pool contract’s enter_delegation_pool function

  • amount should be denominated in FRI (i.e., 1*1018 = 1 STRK)

  • You must first approve the transfer of STRK tokens to the delegation pool contract by invoking the STRK contract’s approve function

Claiming rewards

Invoke the delegation pool contract’s claim_rewards function

Adding to a delegation pool

Invoke the delegation pool contract’s add_to_delegation_pool function

  • amount should be denominated in FRI (i.e., 1*1018 = 1 STRK)

  • You must first approve the transfer of STRK tokens to the delegation pool contract by invoking the STRK contract’s approve function

Switching delegation pools

Invoke the delegation pool contract’s switch_delegation_pool function

Changing reward address

Invoke the delegation pool contract’s change_reward_address function

Exiting a delegation pool

Invoke the delegation pool contract’s exit_delegation_pool_intent and exit_delegation_pool_action function

exit_delegation_pool_action should be invoked only after the appropriate waiting period has ended