Users can submit transactions to an L1 map, but can’t force them. When users “complain” that their transaction is stuck on L1 and not picked up by the sequencer, the Security Council minority can bypass the sequencer by posting a state root that includes it.

State validation

ZK proofs (ST)

STARKs are zero knowledge proofs that ensure state correctness.

Data availability

Onchain (SD)

All of the data (SD = state diffs) needed for proof construction is published onchain.

Exit window

The Security Council can upgrade with no delay.

Standard upgrades are initiated on L1 and go through a 8d delay. In case users are censored, the Security Council minority can be alerted to enforce censorship resistance by submitting a new state root. This process is assumed to take 1d.

Proposer failure

Security Council minority

Only the whitelisted proposer can update state roots on L1, so in the event of failure the withdrawals are frozen. The Security Council minority can be alerted to enforce censorship resistance because they are a permissioned Operator.

Rollup stage

Starknet is a

Stage 1

ZK Rollup.

Learn more about Rollup stages

Please keep in mind that these stages do not reflect rollup security, this is an opinionated assessment of rollup maturity based on subjective criteria, created with a goal of incentivizing projects to push toward better decentralization. Each team may have taken different paths to achieve this goal.

Data availability

All data required to reconstruct rollup state is published on chain

State diffs are publish onchain as blob or calldata on every state update. The state diffs contain information on every contact whose storage was updated, and additional information on contract deployments. From diffs full system state can be recovered. Contracts’ code is not published on L1, but can be trustlessly verified if available elsewhere.

On-Chain Data - Starknet documentation

Learn more about the DA layer here:

Ethereum

State derivation

Node software

The Juno node software can be used to reconstruct the L2 state entirely from L1. The feature has not been released yet, but can be found in this PR.

Compression scheme

Starknet uses stateful compression since v0.13.4.

Genesis state

There is no non-empty genesis state.

Data format

The data format has been updated with different versions, and the full specification can be found here.

State validation

Each update to the system state must be accompanied by a ZK proof that ensures that the new state was derived by correctly applying a series of valid user transactions to the previous state. These proofs are then verified on Ethereum by a smart contract.

Proven Program

The source code of the Starknet OS can be found here. The source code of the bootloader can be found here.

Validity proofs

What is Starknet

Operator

The system has a centralized operator

The operator is the only entity that can propose blocks. A live and trustworthy operator is vital to the health of the system. Typically, the Operator is the hot wallet of the Starknet service submitting state updates for which proofs have been already submitted and verified.

MEV can be extracted if the operator exploits their centralized position and frontruns user transactions.

Users can't force any transaction

There is no general mechanism to force the sequencer to include the transaction.

Users can be censored if the operator refuses to include their transactions.

Censorship resistance of Starknet - Forum Discussion

Withdrawals

Regular messaging

The user initiates L2->L1 messages by submitting a regular transaction on this chain. When the block containing that transaction is settled, the message becomes available for processing on L1. ZK proofs are required to settle blocks. Note that the message request can be censored by the Sequencer.

Funds can be frozen if the operator censors withdrawal transaction.

Withdrawing is based on l2 to l1 messages - Starknet documentation

Emergency exit

There is no generic escape hatch mechanism as Starknet cannot be forced by users into a frozen state. Note that a freezing mechanism on L2, to be secure, requires anti-censorship protection.

Upgrades & Governance

A diagram of the upgrades and governance

The Starknet zk Rollup shares its SHARP verifier with other StarkEx and SN Stack Layer 2s. Governance of the main Starknet rollup contract and its core bridge escrows (ETHBridge, STRKBridge) is currently split between the 9/12 Security Council with instant upgrade capability and the 2/4 Starkware Multisig 2 who can upgrade with a 8d delay. The former Multisig also governs most other bridge escrows with instant upgradeability. The shared SHARP verifier used for state validation can be changed by the 2/4 SHARP Multisig with and a 8d delay, affecting all rollups like Starknet that are sharing it.

The Operator role in the Starknet contract is permissioned to update the state of the Starknet rollup by supplying valid (zk) state transition proofs. Since this role is not permissionless, Starknet implements a StarknetSCMinorityMultisig with the Operator role, which allows a 3/12 minority of the StarknetSecurityCouncil to enforce censorship resistance by including transactions that are not included by regular Operators.

All bridge escrows allow enabling a withdrawal throttle of 5% of the locked funds per 24h period. Enabling it is permissioned to a Multisig while disabling it in the core bridge escrows (STRKBridge, ETHBridge) can be done by a 3/12 minority of the Security Council.

Permissions

A dashboard to explore contracts and permissions

Go to Disco

Explore in Disco

Ethereum

Roles:

Operator (2) Starkware SCMinority Multisig 0x2C16…0CA7

Permissioned to regularly update the state of the L2 on L1. Each state update must have been proven via the SHARP verifier and contains state diffs for data availability.

Governor (2) Starkware Security Council Starkware Multisig 1

Permissioned to manage the Operator role, finalize state and change critical parameters like the programHash, configHash, or message cancellation delay in the core contract.

Starkware Multisig 1 has the role with 8d delay

Actors:

Starkware Multisig 2 0x0152…C6Ec

A Multisig with 2/4 threshold.
Can upgrade with no delay
- StarkgateManager
- StarkgateRegistry
- FXSBridge
- sfrxETHBridge
- FRAXBridge
- MultiBridge
- UNIBridge
Can upgrade with 3d delay
- WBTCBridge
  
  via
  - acting directly with 3d delay
- USDTBridge
  
  via
  - acting directly with 3d delay
- wstETHBridge
  
  via
  - acting directly with 3d delay
- rETHBridge
  
  via
  - acting directly with 3d delay
- USDCBridge
  
  via
  - acting directly with 3d delay
Can interact with StarkgateManager
- enroll new tokens, deactivate existing ones (for deposits) or block tokens from being added to the Multibridge
- manage critical access control roles related to upgrades and set the proxy governor that can upgrade the implementation
Can interact with StarkgateRegistry
- manage critical access control roles and the role that can upgrade the implementation
Can interact with WBTCBridge
- disable the withdrawal limit and manage the security agent role that can enable it
- manage critical access control roles related to upgrades and set the proxy governor that can upgrade the implementation
Can interact with FXSBridge
- disable the withdrawal limit and manage the security agent role that can enable it
- manage critical access control roles related to upgrades and set the proxy governor that can upgrade the implementation
Can interact with USDTBridge
- disable the withdrawal limit and manage the security agent role that can enable it
- manage critical access control roles related to upgrades and set the proxy governor that can upgrade the implementation
Can interact with wstETHBridge
- disable the withdrawal limit and manage the security agent role that can enable it
- manage critical access control roles related to upgrades and set the proxy governor that can upgrade the implementation
Can interact with rETHBridge
- disable the withdrawal limit and manage the security agent role that can enable it
- manage critical access control roles related to upgrades and set the proxy governor that can upgrade the implementation
Can interact with sfrxETHBridge
- disable the withdrawal limit and manage the security agent role that can enable it
- manage critical access control roles related to upgrades and set the proxy governor that can upgrade the implementation
Can interact with FRAXBridge
- disable the withdrawal limit and manage the security agent role that can enable it
- manage critical access control roles related to upgrades and set the proxy governor that can upgrade the implementation
Can interact with LUSDBridge
- disable the withdrawal limit and manage the security agent role that can enable it
- manage critical access control roles related to upgrades and set the proxy governor that can upgrade the implementation
Can interact with MultiBridge
- disable the withdrawal limit and manage the security agent role that can enable it
- manage critical access control roles related to upgrades and set the proxy governor that can upgrade the implementation
Can interact with USDCBridge
- disable the withdrawal limit and manage the security agent role that can enable it
- manage critical access control roles related to upgrades and set the proxy governor that can upgrade the implementation
Can interact with UNIBridge
- disable the withdrawal limit and manage the security agent role that can enable it
- manage critical access control roles related to upgrades and set the proxy governor that can upgrade the implementation

Participants (4):

0xd388…d3F8 0x5923…8558 0xCe95…23a0 0x64F4…5770

Starkware Security Council 0x15e8…C361

A Multisig with 9/12 threshold.
Can upgrade with no delay
- ETHBridge
- Starknet
- STRKBridge
Can interact with ETHBridge
- manage critical access control roles related to upgrades and set the proxy governor that can upgrade the implementation
Can interact with STRKBridge
- manage critical access control roles related to upgrades and set the proxy governor that can upgrade the implementation
A Governor - acting directly

Participants (12):

0x0762…F09c 0x5C7D…252F 0x04D5…F94c 0x2914…751d 0xfaEC…33B0 0xF6AB…FbD8 0x16aB…57CD 0x1027…8cac 0x7383…E560 0x590C…430C 0x7A3a…982E 0xFf71…0D90

Security Council members - Starkware Governance Hub

Starkware Multisig 1 0x83C0…e988

A Multisig with 2/6 threshold.
Can upgrade with 8d delay
- ETHBridge
  
  via
  - acting via DelayedExecutor with 8d delay
- Starknet
  
  via
  - acting via DelayedExecutor with 8d delay
- STRKBridge
  
  via
  - acting via DelayedExecutor with 8d delay
A Governor - acting via DelayedExecutor with 8d delay

Participants (6):

0xaDB2…38fc 0x8e81…7Dd5 0x804d…C81f 0x2871…B403 0x64F4…5770 0x5923…8558

Starkware SCMinority Multisig 0xF6b0…bC6B

A Multisig with 3/12 threshold.
Can interact with ETHBridge
- disable the withdrawal limit and manage the security agent role that can enable it
Can interact with STRKBridge
- disable the withdrawal limit and manage the security agent role that can enable it
An Operator - acting directly

Participants (12):

0x2914…751d 0x04D5…F94c 0x5C7D…252F 0x0762…F09c 0xfaEC…33B0 0xF6AB…FbD8 0x16aB…57CD 0x1027…8cac 0x7383…E560 0x590C…430C 0x7A3a…982E 0xFf71…0D90

SHARP Multisig 0x21F9…AEc4

A Multisig with 2/4 threshold.
Can upgrade with 8d delay
- SHARPVerifierCallProxy
  
  via
  - acting directly with 8d delay

Participants (4):

0x0405…8488 0x5923…8558 0xebc8…fD7F 0x955B…2Fec

Used in:

StarkgateManager 0x0c5a…5B60

Acts as a central contract to manage StarkGate bridge escrows (add new ones, deactivate existing, change configs) when given the Manager role from the respective escrows.
Can interact with MultiBridge
- enroll new tokens or deactivate deposits into the escrow (for each token individually)

Starkware Multisig 4 0x77Dd…88c5

A Multisig with 1/3 threshold.

Participants (3):

EOA 1 0x5923…8558 EOA 2

EOA 1 0x030c…5755

Member of Starkware Multisig 4.
Can interact with WBTCBridge
- enable the withdrawal limit
  
  via
  - acting via Starkware Multisig 4
Can interact with ETHBridge
- enable the withdrawal limit
  
  via
  - acting via Starkware Multisig 4
Can interact with USDTBridge
- enable the withdrawal limit
  
  via
  - acting via Starkware Multisig 4
Can interact with STRKBridge
- enable the withdrawal limit
  
  via
  - acting via Starkware Multisig 4
Can interact with MultiBridge
- enable the withdrawal limit
  
  via
  - acting via Starkware Multisig 4
Can interact with USDCBridge
- enable the withdrawal limit
  
  via
  - acting via Starkware Multisig 4

EOA 2 0x35FD…4a7b

Member of Starkware Multisig 4.
Can interact with WBTCBridge
- enable the withdrawal limit
  
  via
  - acting via Starkware Multisig 4
Can interact with ETHBridge
- enable the withdrawal limit
  
  via
  - acting via Starkware Multisig 4
Can interact with USDTBridge
- enable the withdrawal limit
  
  via
  - acting via Starkware Multisig 4
Can interact with STRKBridge
- enable the withdrawal limit
  
  via
  - acting via Starkware Multisig 4
Can interact with MultiBridge
- enable the withdrawal limit
  
  via
  - acting via Starkware Multisig 4
Can interact with USDCBridge
- enable the withdrawal limit
  
  via
  - acting via Starkware Multisig 4

EOA 4 0x5751…f21A

Can upgrade with no delay
- LUSDBridge

Used in:

Smart contracts

A dashboard to explore contracts and permissions

Go to Disco

Explore in Disco

A diagram of the smart contract architecture

Ethereum

Starknet 0xc662…C8c4 Implementation (Upgradable)Admin Admin

Central rollup contract. Receives (verified) state roots from the Sequencer, allows users to consume L2 -> L1 messages and send L1 -> L2 messages. Critical configuration values for the L2’s logic are defined here by various governance roles.

Can be upgraded by:

Starkware Security Council with no delay Starkware Multisig 1 with 8d delay

Implementation used in:

SHARPVerifierCallProxy 0x4731…Db60 Implementation (Upgradable)Admin

Upgradable call proxy contract through which the SHARPVerifier can be called. A call proxy does not delegatecall and the storage context remains at the target contract. It allows SHARP Multisig to change the otherwise immutable verifier contract with 8d delay.

Can be upgraded by:

SHARP Multisig with 8d delay

Proxy used in:

SHARPVerifier 0x9fb7…1942

Shared Starkware SHARP verifier used collectively by Starknet and other SN stack and StarkEx projects. It receives STARK proofs from the Prover and verifies the integrity of the offchain execution including a correctly computed state root which is part of the Program Output.

Proxy used in:

DelayedExecutor 0xCA11…Ca0c

A simple Timelock contract with an immutable delay of 8d. The owner (Starkware Multisig 1) can queue transactions.
Can act as a Governor.
Can be used to upgrade implementation of ETHBridge, Starknet, STRKBridge.

ETHBridge 0xae0E…D419 Implementation (Upgradable)Admin Admin

Standard Starkware canonical bridge escrow for ETH. Withdrawals can be throttled to 5% of the locked funds per 24 hours. This contract stores the following tokens: ETH.

Can be upgraded by:

Starkware Security Council with no delay Starkware Multisig 1 with 8d delay

LORDSBridge 0x023A…E5C9

Custom (and immutable) entry point contract and escrow for users depositing LORDS to via StarkGate to the L2. This contract stores the following tokens: LORDS.

StarkgateRegistry 0x1268…6812 Implementation (Upgradable)Admin

A simple registry that maps tokens to their StarkGate escrows. It also keeps a list of tokens that are blocked from being added to StarkGate.

Can be upgraded by:

Starkware Multisig 2 with no delay

WBTCBridge 0x2837…b5b4 Implementation (Upgradable)Admin

Standard Starkware bridge escrow (single token). Withdrawals can be throttled to 5% of the locked funds per 24 hours. This contract stores the following tokens: WBTC.

Can be upgraded by:

Starkware Multisig 2 with 3d delay

FXSBridge 0x66ba…0B7C Implementation (Upgradable)Admin

Standard Starkware bridge escrow (single token). Withdrawals can be throttled to 5% of the locked funds per 24 hours. This contract stores the following tokens: FXS.

Can be upgraded by:

Starkware Multisig 2 with no delay

L1DaiGateway 0x9F96…388d

Gateway contract that is the user entrypoint to deposit DAI to a custom escrow to bridge via StarkGate.

USDTBridge 0xbb34…7605 Implementation (Upgradable)Admin

Standard Starkware bridge escrow (single token). Withdrawals can be throttled to 5% of the locked funds per 24 hours. This contract stores the following tokens: USDT.

Can be upgraded by:

Starkware Multisig 2 with 3d delay

wstETHBridge 0xBf67…985B Implementation (Upgradable)Admin

Standard Starkware bridge escrow (single token). Withdrawals can be throttled to 5% of the locked funds per 24 hours. This contract stores the following tokens: wstETH.

Can be upgraded by:

Starkware Multisig 2 with 3d delay

STRKBridge 0xcE54…C7a4 Implementation (Upgradable)Admin Admin

Standard Starkware bridge escrow (single token). Withdrawals can be throttled to 5% of the locked funds per 24 hours. This contract stores the following tokens: STRK.

Can be upgraded by:

Starkware Security Council with no delay Starkware Multisig 1 with 8d delay

rETHBridge 0xcf58…76C2 Implementation (Upgradable)Admin

Standard Starkware bridge escrow (single token). Withdrawals can be throttled to 5% of the locked funds per 24 hours. This contract stores the following tokens: rETH.

Can be upgraded by:

Starkware Multisig 2 with 3d delay

sfrxETHBridge 0xd8E8…8Ee8 Implementation (Upgradable)Admin

Standard Starkware bridge escrow (single token). Withdrawals can be throttled to 5% of the locked funds per 24 hours. This contract stores the following tokens: sfrxETH.

Can be upgraded by:

Starkware Multisig 2 with no delay

FRAXBridge 0xDc68…1ebb Implementation (Upgradable)Admin

Standard Starkware bridge escrow (single token). Withdrawals can be throttled to 5% of the locked funds per 24 hours. This contract stores the following tokens: FRAX.

Can be upgraded by:

Starkware Multisig 2 with no delay

LUSDBridge 0xF3F6…3DF5 Implementation (Upgradable)Admin

Standard Starkware bridge escrow (single token). Withdrawals can be throttled to 5% of the locked funds per 24 hours. This contract stores the following tokens: LUSD.

Can be upgraded by:

EOA 4 with no delay

MultiBridge 0xF5b6…69Eb Implementation (Upgradable)Admin

Starkware Multibridge escrow. Withdrawals can be throttled to 5 of the locked funds per 24 hours for each token individually. This contract stores the following tokens: EKUBO, ZEND, NSTR.

Can be upgraded by:

Starkware Multisig 2 with no delay

USDCBridge 0xF608…2816 Implementation (Upgradable)Admin

Standard Starkware bridge escrow (single token). Withdrawals can be throttled to 5% of the locked funds per 24 hours. This contract stores the following tokens: USDC.

Can be upgraded by:

Starkware Multisig 2 with 3d delay

UNIBridge 0xf76e…236B Implementation (Upgradable)Admin

Standard Starkware bridge escrow (single token). Withdrawals can be throttled to 5% of the locked funds per 24 hours. This contract stores the following tokens: UNI.

Can be upgraded by:

Starkware Multisig 2 with no delay

DAIBridge 0x0437…585C

Simple escrow that accepts tokens and allows to configure permissioned addresses that can access the tokens. This contract stores the following tokens: DAI.

MemoryPageFactRegistry 0xe583…C460

Auxiliary to the SHARPVerifier contract: Verified ‘memory fact pages’ get stored here. This is important as it registers all necessary onchain data produced by the verifier.