The BOB page of Bitcoin Layers is under development.
Bitcoin Layers' focuses its efforts on reviewing protocols that claim to be a bitcoin layer and BTC wrappers that live on alternative chains. Alternative network provide a snapshot into the network architecture, but largely focus on review related to BTC wrappers on the network. If the network is an Ethereum L2, we recommend heading to L2Beat for a deeper dive into the architecture.
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BOB
Overview
Status
Mainnet
Type
Alt. Rollup
Fee Token
ETH
BTC Supply
₿0
BOB prioritizes use cases for BTC-backed assets and is looking to derive more security from bitcoin over time. The network is an alternative rollup. It uses an alternative network for data availability and consensus. It supports a variety of BTC-backed assets.
CUSTODY
DATA AVAILABILITY
OPERATORS
FINALITY ASSURANCE
BTC Supply
Total supply per day
Supplycoming soon
TVL Data Coming Soon
We're currently gathering and building data infrastructure for this network. TVL analytics will be available soon.
Token Contracts
Token Contracts Coming Soon
We're working to collect the various BTC-backed token contracts for this network. Contract addresses will be available soon.
Risk Summary
All BTC pegs have custodian trust assumptions
All BTC backing wrapped tokens on this network are ultimately secured by custodians. Users trust that these custodians will not misappropriate funds and keep their assets pegged 1:1. Each custodian has their own risks. Learn more in the trust assumptions review section.
Bridge contracts are upgradeable
A centralized party can immediately upgrade specific system contracts. This risk may be relevant to BTC-backed tokens locked in the layer's official bridge contract.
Another data availability layer is used
Data related to the network's state is made available by another consensus network. The network's state cannot make progress if the data availability layer withholds the data. If the network cannot make progress, user funds can be frozen.
A centralized entity is the network operator
The network is operated by a centralized operator. If this operator goes offline, the network can be halted which can freeze user funds. Please see the trust assumptions to learn if their is a fallback mechanism for liveness failures.
Categorization
The project does not have an enshrined bitcoin bridge
The project does not have an enshrined bitcoin bridge that meets our sidesystem standards. Our standards require sidesystem's enshinred bridge programs to have at least 5 signers with 4 of those signers being external to the project's primary development organization.
Trust Assumption Review
BTC Custody
Very High
🛑
BTC users trust that tBTC will remain backed on Ethereum, and that that the BOB bridge will not be maliciously upgraded
tBTC's peg with bitcoin is managed by the Threshold Network, a distributed but permissioned two-way peg. This group of signers participate in a threshold signature scheme to secure the BTC that backs tBTC. tBTC is minted via its official bridge between BOB and Ethereum. This bridge is finalized by a Hybrid proving system using validity proofs and fraud proofs.
A centralized admin can create a malicious smart contract upgrade. In the event of a malicious smart contract upgrade, there is no exit window for users. This means that the admin behind the bridge can steal all funds in the official bridge.
A centralized admin can create a malicious smart contract upgrade. In the event of a malicious smart contract upgrade, there is no exit window for users. This means that the admin behind the bridge can steal all funds in the official bridge.
Learn more about Threshold tBTC's custody model→
Data Availability
Medium
⚠️
Data is stored and made available by Ethereum full nodes
The data for network's state is made available by Ethereum full nodes. Anyone can run an Ethereum node and verify the state of the network.
Network Operators
High
🚨
BOB blocks are produced and proposed by a centralized operator, but forced inclusion to Ethereum L1 possible
The network's sequencer is managed by one entity. The sequencer can censor transactions and can also cause liveness failures if it goes down. Users can bypass the sequencer and force include their transaction to be included in an upcoming sequence.
Finality Guarantees
Medium
⚠️
Bob's state transitions finalize by updating its state based on data posted to Ethereum
State transitions are finalized by an alternative consensus mechanism with a distributed validator set.
Finality is not necessarily through the lens of a validating bridge
The network is an alternative rollup. This means it uses another blockchain for data availability. From the view of its full nodes, the rollup's state is finalized after it it validates state updates published to the data availability layer. Therefore, the network's finality assurances are that of its data availability layer (assuming the node operation is permissionless). A state root may be additionally posted to the data availability layer to finalize bridge programs, but this is not a guarantee of finality. This guarantee ensures the network's bridge programs are secure and can permit withdrawals based on the network's state. This only applies to tokens that are locked in these specific's bridge programs. See the BTC custody section for more information.
Bitcoin Security
BOB does not inherit any security from Bitcoin
In its current state, the network does not inherit security from Bitcoin.
ETH token used to pay fees
Fees to network operators are paid in an alternative token.
No MEV introduced to Bitcoin
The network does not introduce any MEV on the Bitcoin L1. Users trust the sequencer to not reorder their transactions to extract MEV.
BOB does not contribute to the security budget
The network does not currently contribute to the Bitcoin security budget.
Withdrawals
Proposer role centralized and permissioned. BTC users trust network operators to include their withdrawal requests in a block. Asset redemption varies dependent on the asset issuer
Withdrawing BTC-backed assets from the network depends on a variety of factors. First, users must trust the network operators to include their withdrawal request in a block. If the user's assets are locked in the network's official bridge program, they rely on a proposer to include their request in proposed state transition. After the state transition is finalized, the user can redeem their funds.
If a user's BTC-backed asset is minted directly onto the network, then the user's withdrawal request must be processed by the asset issuer.
If a user's BTC-backed asset is minted directly onto the network, then the user's withdrawal request must be processed by the asset issuer.
Technology
Ethereum Virtual Machine
The network uses an EVM-compatible virtual machine. The Ethereum Virtual Machine is software responsible for smart contract execution for a number of blockchains, namely the Ethereum Network. It uses Solidity/Vyper as its code and is the dominant environment for smart contract execution in the cryptocurrency ecosystem.
OP Kailua
BOB leverages a hybrid proving system that leverages validity proofs and fraud proofs to finalize bridge programs on Ethereum. The system leverages a priveleged proposer, known as the Vanguard, that has the first right to submit a state update to BOB smart contracts on Ethereum. It can either submit a validity proof to finalize the state update after a verifier contract verifies the proof, or it can submit a state root that is validated after a challenge window passes. If only a state root is submitted, it finalizes after three days. Anyone is able to challenge this proposal by submitting a conflicting state update proposal. In the event of a challenge proposal, the Vanguard or the challenger submit a validity proof that is verified by an Ethereum smart contract. Only a correct proposal can be validated by the verifier contract, so only the correct proposal is accepted to advance the state. The publisher of an incorrect state update is slashed the 0.5 ETH collateral they posted.
Learn more about OP Kailua
L2Beat has a great overview of the hybrid proving system used by BOB.
Use Cases
Onchain applications
Onchain applications are supported. Onchain applications include borrowing and lending protocols, onchain exchanges (commonly referred to as decentralized exchanges), and more. These applications are supported with more expressive smart contract environments.
Source Code
Under review
We are reviewing if BOB's node software is open-source.
Knowledge Bits
Learn more
This document outlines the privileged roles who play a role in managing various components of the BOB chain
A risk review of the OP Mainnet chain on Ethereum, which has similar trust assumptions as the BOB chain as BOB is built on the OP Stack
A blog covering R&D areas related to Bitcoin security on BOB.
BOB's TVL breakdown, including total BTC locked.
A risk review of the OP Mainnet chain on Ethereum, which has similar trust assumptions as the BOB chain as BOB is built on the OP Stack
A blog covering R&D areas related to Bitcoin security on BOB.
BOB's TVL breakdown, including total BTC locked.