Trust Bitcoin Info
Trust Bitcoin has an edge in DeFi services because of its best-in-class offerings. With the likes of services like mining, smart contracts, digital wallets, governance and creating dApps. Also, miners will have exceptional benefits for adding a block to the Trust Bitcoin blockchain.
Team and KYC Verification
The team has securely submitted their personal information to SolidProof.io for verification.
In the event of any fraudulent activities, this information will be promptly reported to the relevant authorities to ensure accountability and compliance.
TrustNet Score
The TrustNet Score evaluates crypto projects based on audit results, security, KYC verification, and social media presence. This score offers a quick, transparent view of a project's credibility, helping users make informed decisions in the Web3 space.
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Security Assessments
Summary and Final Words
No crucial issues found
The contract does not contain issues of high or medium criticality. This means that no known vulnerabilities were found in the source code.
Ownership is not renounced
The owner retains significant control, which could potentially be used to modify key contract parameters.
Contract is not upgradeable
The contract does not use proxy patterns or other mechanisms to allow future upgrades. Its behavior is locked in its current state.
Scope of Work
This audit encompasses the evaluation of the files listed below, each verified with a SHA-1 Hash. The team referenced above has provided the necessary files for assessment.
The auditing process consists of the following systematic steps:
- Specification Review: Analyze the provided specifications, source code, and instructions to fully understand the smart contract's size, scope, and functionality.
- Manual Code Examination: Conduct a thorough line-by-line review of the source code to identify potential vulnerabilities and areas for improvement.
- Specification Alignment: Ensure that the code accurately implements the provided specifications and intended functionalities.
- Test Coverage Assessment: Evaluate the extent and effectiveness of test cases in covering the codebase, identifying any gaps in testing.
- Symbolic Execution: Analyze the smart contract to determine how various inputs affect execution paths, identifying potential edge cases and vulnerabilities.
- Best Practices Evaluation: Assess the smart contracts against established industry and academic best practices to enhance efficiency, maintainability, and security.
- Actionable Recommendations: Provide detailed, specific, and actionable steps to secure and optimize the smart contracts.
A file with a different Hash has been intentionally or otherwise modified after the security review. A different Hash may indicate a changed condition or potential vulnerability that was not within the scope of this review.
Final Words
The following provides a concise summary of the audit report, accompanied by insightful comments from the auditor. This overview captures the key findings and observations, offering valuable context and clarity.
Smart Contract Analysis Statement
Contract Analysis
The BNBBridge contract implements the BNB Smart Chain side of a burn-and-release bridge to the TBC Network. Users burn WTBC to receive native TBC on the TBC Network, and send USDT or USDC to a dedicated fund wallet to receive AUSD there. In the other direction the contract mints WTBC and pays stablecoins out of the fund wallet. Every inbound transfer needs a signed message from the source verifier that binds the complete source transfer, on top of separate operator, verifier and executor roles with waiting periods of fifteen minutes each, and each source transfer can be released only once. WTBC minting and stablecoin payouts draw on rolling daily budgets, and stablecoin payouts for AUSD are also limited to the backing recorded from deposits and a one-time opening balance.
The contract is deployed at 0x0e47d5E9BFEFA300ea068c972351265D0a604Fb8. It is not upgradeable, charges no fees, has no blacklist and cannot raise any rate. The verified source code reproduces the deployed bytecode exactly, including the metadata hash, and differs from the reviewed code only in one documentation comment, which confirms that what is on-chain is what was reviewed. At the time of review the bridge was deployed but not yet configured for operation.
Ownership Privileges
The admin role is held by a timelock with a twelve hour delay that is owned by a Gnosis Safe requiring three of its four signers, while day-to-day release authority requires the source verifier's signature together with separate operator, verifier and executor roles, which had not yet been assigned at the time of review. The owner retains full privileges including:
- The admin can configure routes, budgets and exemptions, replace the fund wallet and the source verifier, rescue tokens other than WTBC, set the opening balance of the redemption backing once and grant any role; every such change has to pass the twelve hour timelock
- A compromise of the source verifier key together with the three role keys would allow WTBC minting and stablecoin payouts within the daily budgets and the recorded backing; the source verifier is a single externally owned account
- Refunds of failed transfers need both the source verifier's signature and a verifier key, and stop while the bridge is paused
- The guardian, a Safe that needs all three of its signers, can pause the bridge and void signatures that have already been issued
- User stablecoins are held by a fund wallet that is a Safe requiring three of its four signers, and payouts are pulled through its allowance
- The opening balance of the redemption backing is a trusted input that the contract cannot verify
- No fees exist in the contract and none can be introduced
- There is no blacklist and no way to freeze an individual balance
Security Features
The contract implements several positive security features:
- Every function that moves value is protected against reentrancy and all token transfers use safe transfer wrappers
- Inbound releases require a typed signature over the complete source transfer, and each source transfer can be consumed only once
- Rolling daily budgets bound WTBC minting and stablecoin payouts, and stablecoin payouts for AUSD cannot exceed the recorded backing
- A release that cannot be delivered is parked instead of blocking the others, and failed transfers can be refunded on-chain
- A two-chain test suite with the production token code confirmed within the tested scenarios that releases, refunds, budgets and the redemption backing behave as intended, including every failure case found in earlier reviews
Points Requiring Attention
All high and medium issues of the earlier reviews are resolved; the points below remain.
One issue was rated low. A cancelled transfer larger than the WTBC budget limit cannot be refunded until the admin raises the limit through the timelock and the budget has refilled.
Note - This Audit report consists of a security analysis of the BNBBridge smart contract. This analysis did not include economic analysis of the contract's tokenomics. Moreover, we only audited the main contract for the Trust Bitcoin team. Other contracts associated with the project were not audited by our team - in particular the WTBC token, the admin timelock, the Safe wallets and the off-chain relayer, all of which this contract depends on. We recommend investors do their own research before investing.
Files and details
Findings and Audit result
low Issues | 1 findings
Pending
#1 low Issue
A cancelled transfer above the WTBC budget limit cannot be refunded
Refunds that mint WTBC now draw on the rolling WTBC budget, and the budget rejects any amount above its limit. bridgeWTBC accepts any amount above the route minimum, while the TBC Network refuses to insert a release above its native budget limit, so such a transfer can only be cancelled. If the WTBC limit is also below the amount, the refund reverts on every attempt, the request stays pending and the burned WTBC is not minted back until the admin raises the WTBC limit behind the timelock and the budget has refilled, because raising the limit does not refill the bucket. A test reproduces this with 400 WTBC limits on both chains and a 500 WTBC transfer.