Code Audit
Bitcoin Audit Services
From custody wallets to cross-chain bridges, our Bitcoin audits combine code review, infrastructure testing, and operational checks to harden your project against real-world threats.
150+
audits
completed
$10B+
in client
assets protected
$200B+
in transacted
value secured
300+
crit / high issues found
Consolidated clients
What is a Bitcoin Audit?
A Bitcoin security audit is a comprehensive review focused on identifying vulnerabilities, inefficiencies, and risks in Bitcoin-based systems. Whether your project integrates Bitcoin transactions, builds BTC custody infrastructure, operates a multi-signature wallet, or connects through sidechains and bridges, an audit ensures your implementation is secure, reliable, and production-ready.For full 360º security coverage, we recommend extending the scope to include an OpSec Audit and a dApp Frontend Audit.
Why a Bitcoin Audit Matters
Bitcoin is the most valuable and widely used cryptocurrency in the world, making it a prime target for attackers. Projects that handle BTC must meet the highest possible security standards because blockchain transactions are irreversible.
A single flaw can result in:
Unrecoverable financial losses
Severe reputational damage
Regulatory and compliance scrutiny
Our Bitcoin protocol audits address these risks before attackers can exploit them, giving your team confidence that on-chain and off-chain components are secure. For teams that
Our Approach to Bitcoin Audit Security
Choosing a blockchain audit partner it’s not just about getting a security report, it’s about trusting someone to protect everything you built. Every Bitcoin audit from Three Sigma delivers more than just a PDF. As a Web3 audit firm, we strengthen your systems against known and emerging threats, improve operational security, align with industry best practices, and give your team crystal-clear guidance they can act on immediately.
Each Three Sigma audit is tailored to your needs, architecture, ecosystem, and use case. Whether your project runs on:
We account for unique language risks, dependency interactions, and upgradeability concerns. Our process is designed not just to identify problems but to provide practical, high-impact recommendations that make your contracts more secure, efficient, and resilient.
Common Issues Found in Bitcoin Audits
Flawed transaction signing or serialization logic
Often caused by incorrect implementation of Bitcoin’s raw transaction format or signature hashing (SIGHASH).
Insecure multi-signature implementations
Poor handling of Bitcoin script, threshold logic, or address derivation leaves funds exposed to bypass or misuse.
Misuse of SegWit or P2SH addresses
Errors in script construction or witness data can make transactions invalid or funds unspendable.
Replace-by-Fee (RBF) handling errors
Incorrect mempool logic or fee bumping policies let attackers double-spend or disrupt settlement.
Cross-chain bridge verification flaws
Weak validation of Bitcoin block headers, SPV proofs, or confirmations creates exploitable trust assumptions.
Poor private key storage practices
Inadequate use of HSMs, hardware wallets, or secure enclaves increases risk of key theft or loss.
Outdated or misconfigured Bitcoin nodes
Nodes lacking recent consensus rules, patches, or hardened configs are vulnerable to consensus splits or denial-of-service.
Weak APIs exposing sensitive operations
Exposing wallet functions like `sendrawtransaction` or key signing endpoints allows unauthorized access to critical Bitcoin operations.
Common vulnerabilities can compromise assets or disrupt service. Our Bitcoin audit services are designed to find and fix them. Bitcoin systems face unique attack surfaces:
Our Bitcoin Audit Process
Scoping and Planning
We define the audit scope around custody flows, wallet models, bridges, and transaction handling
Architecture Review
We assess transaction logic, multi-sig design, key management, and node interactions.
Code Review
We check wallet and custody code for issues in serialization, signing, cryptography, and APIs.
Testing and Simulation
We run fuzzing, exploit tests, and forked-network simulations to catch flaws, including RBF handling.
Reporting & Recommendations
We deliver a severity-ranked Bitcoin audit report with clear fixes.
Verification
We confirm applied fixes and ensure vulnerabilities are resolved.
Deliverables You Can Expect
As part of a Three Sigma Bitcoin audit, you receive a comprehensive technical report detailing all vulnerabilities with clear severity ratings, accompanied by code-level remediation guidance for your developers. The engagement also contains tailored infrastructure and operations recommendations, an executive summary for non-technical stakeholders.
Post-audit support is included
Post-audit support is included with the option for full verification of fixes before deployment.
Discover how we protect teams like yours in our Case Studies.
What You Gain
from a Three Sigma Audit
Our bitcoin audit is more than just a checkmark on your roadmap, it’s an investment in your project’s success.
Protection against financial and reputational loss
Stronger compliance posture and investor confidence
A secure foundation for Bitcoin custody, DeFi protocols, and cross-chain systems
Assurance that your Bitcoin-related infrastructure is hardened against threats
Industries We Secure
Our audits have helped secure decentralized applications across multiple verticals.
DeFi &
Liquidity
Lending platforms, DEXes, staking, and collateral markets.
NFT &
Collectibles
Marketplaces, launchpads, minting tools, and creator hubs.
Gaming &
Metaverse
Play-to-earn games, trading hubs, and immersive 3D worlds.
Cross-Chain Infrastructure
Bridges, oracle networks, and cross-chain protocol layers.
Frequently Asked Questions
Check out the Blockchain Protocol Security Audit F.A.Q.
What is included in a Bitcoin audit?
A Bitcoin audit examines code, infrastructure, and operations that process BTC transactions or integrate with the Bitcoin network.
How long does a Bitcoin audit take?
Most engagements take 2–6 weeks, depending on scope and complexity.
Who needs a Bitcoin audit?
Exchanges, custodial wallets, payment processors, DeFi platforms, and cross-chain projects handling BTC benefit from audits.
How is a Bitcoin audit different from a smart contract audit?
Smart contract audits target EVM or Move-based code. A Bitcoin audit also covers transaction validation, node configs, and custody logic.
How much does a Bitcoin audit cost?
Cost depends on system size and complexity. Larger integrations require more extensive testing.