2022 Jul 13th

DeversiFi becomes rhino.fi: multi-chain platform gathering DeFi in one place.

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DeversiFi Relaunched using Starkware

2020 Jun 3rd

DeversiFi is live, bringing first STARKex Validium for spot trading.

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Knowledge Nuggets


rhino.fi (formerly DeversiFi) claims to be the easiest way to access DeFi opportunities on Ethereum: invest, trade, and send tokens without paying gas fees.

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Risk Analysis

Sequencer failureState validationData availabilityUpgradeabilityProposer failure

State validation

ZK proofs (ST)

ZK-STARKS are zero knowledge proofs that ensure state correctness.

Data availability

External (DAC)

Proof construction relies fully on data that is NOT published on chain. There exists a data availability committee (DAC) that is tasked with protecting and supplying the data.


14d delay

The code that secures the system can be changed arbitrarily but users have some time to react.

Sequencer failure

Force via L1

Users can force the sequencer to include a withdrawal transaction by submitting a request through L1. If the sequencer censors or is down for for more than 7d, users can use the exit hatch to withdraw their funds.

Proposer failure

Use escape hatch

Users are able to trustlessly exit by submitting a Merkle proof of funds.


Validity proofs ensure state correctness

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. Once the proof is processed on the Ethereum blockchain the L2 block is instantly finalized. The system state is represented using Merkle roots.

  1. Enforcing Consistency on the On-Chain State - StarkEx documentation

Zero knowledge STARK cryptography is used

Despite their production use ZK-STARKs proof systems are still relatively new, complex and they rely on the proper implementation of the polynomial constraints used to check validity of the Execution Trace.

  • Funds can be lost if the proof system is implemented incorrectly.

  1. STARK Core Engine Deep Dive

Data is not stored on chain

The balances of the users are not published on-chain, but rather sent to several well known and trusted parties, also known as committee members. A state update is valid and accepted on-chain only if at least a quorum of the committee members sign a state update.

  • Funds can be lost if the external data becomes unavailable (CRITICAL).

  • Users can be censored if the committee restricts their access to the external data.

  1. Data Availability Modes - StarkEx documentation
  2. Validium - StarkEx documentation
  3. Availability Verifiers - StarkEx documentation


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 StarkEx 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.

  1. Operator - StarkEx documentation

Users can force exit the system

Force exit allows the users to escape censorship by withdrawing their funds. The system allows users to force the withdrawal of funds by submitting a request directly to the contract on-chain. The request must be served within a defined time period. If this does not happen, the system will halt regular operation and permit trustless withdrawal of funds.

  • Users can be censored if the operator refuses to include their transactions. They can still exit the system.

  1. Censorship Prevention - StarkEx documentation


Regular exit

The user initiates the withdrawal by submitting a transaction on L2. When the block containing that transaction is proven the funds become available for withdrawal on L1. Finally the user submits an L1 transaction to claim the funds. This transaction does not require a merkle proof.

  1. Withdrawal - StarkEx documentation

Forced exit

If the user experiences censorship from the operator with regular exit they can submit their withdrawal requests directly on L1. The system is then obliged to service this request. Once the force operation is submitted if the request is serviced the operation follows the flow of a regular exit.

  1. Forced Operations - StarkEx documentation
  2. Forced Withdrawal - StarkEx documentation
  3. Forced Trade - StarkEx documentation

Emergency exit

If enough time passes and the forced exit is still ignored the user can put the system into a frozen state, disallowing further state updates. In that case everybody can withdraw by submitting a merkle proof of their funds with their L1 transaction.

  1. Forced Operations - StarkEx documentation
  2. Forced Withdrawal - StarkEx documentation
  3. Forced Trade - StarkEx documentation


The system uses the following set of permissioned addresses:

Can upgrade the implementation of the system, potentially gaining access to all funds stored in the bridge. Currently there is 14d delay before the upgrade.

Validity proof must be signed by at least 4 of these addresses to approve state update.

SHARP Verifier Governors 0x3DE5…F5C60x21F9…AEc4

Can upgrade implementation of SHARP Verifier, potentially with code approving fraudulent state. Currently there is 28d delay before the upgrade.

SHARPVerifierGovernorMultisig 0x21F9…AEc4

SHARP Verifier Governor. This is a Gnosis Safe with 2 / 3 threshold.

SHARPVerifierGovernorMultisig participants 0x5923…85580xebc8…fD7F0x955B…2Fec

Those are the participants of the SHARPVerifierGovernorMultisig.

Operators 0x8A6c…6ae5

Allowed to update the state of the system. When the Operator is down the state cannot be updated.

Smart Contracts

A diagram of the smart contract architecture
A diagram of the smart contract architecture

The system consists of the following smart contracts:

This contract can store any token.

Committee 0x2878…4306

Data Availability Committee (DAC) contract verifying data availability claim from DAC Members (via multisig check).

CallProxy for GpsStatementVerifier.

SHARPVerifier 0x6cB3…1BF6

Starkware SHARP verifier used collectively by Starknet, Sorare, ImmutableX, Apex, Myria, rhino.fi and Canvas Connect. It receives STARK proofs from the Prover attesting to the integrity of the Execution Trace of these Programs including correctly computed L2 state root which is part of the Program Output.

FriStatementContract 0x3E61…d2DD

Part of STARK Verifier.

MerkleStatementContract 0x5899…5fa4

Part of STARK Verifier.

MemoryPageFactRegistry 0xFD14…D1b4

MemoryPageFactRegistry is one of the many contracts used by SHARP verifier. This one is important as it registers all necessary on-chain data.

CairoBootloaderProgram 0x5d07…9dDf

Part of STARK Verifier.

The current deployment carries some associated risks:

  • Funds can be stolen if a contract receives a malicious code upgrade. There is a 14d delay on code upgrades.