Secure Your Crypto Exchange with Air-Gapped Cold Storage and Multisig

Losing $190 million due to a hot wallet hack is not an isolated incident. Exchanges that have not implemented cold storage lose millions annually. Developing a cold storage system for a crypto exchange is the only way to protect 90% of reserves from remote attacks. Our cold storage exchange development includes multisig wallets and air gap systems. We also provide SOP withdrawal procedures and HSM for exchange security. Reserve protection is our top priority, and we conduct exchange security audits to identify any hot wallet vulnerability. We build systems with air-gapped architecture, multisig, and hardware HSM. Statistics show that 95% of exchange hacks involve hot wallets, so isolating critical assets is not a luxury but a necessity. Our certified team with 10+ years of experience has implemented 15+ cold storage systems for exchanges of various sizes.

Air gap is a network security measure that involves physically isolating a secure network from unsecured networks. — Wikipedia

How does an air-gapped system work?

Air gap is complete physical isolation: the transaction signing computer is never connected to the internet. This approach eliminates remote hacking. Wikipedia defines this method as one of the most secure. In our practice, we use QR codes to transfer transactions rather than USB to avoid BadUSB attacks. Using an air-gapped system is 1000 times more secure than relying solely on hot wallets.

Transaction signing workflow:

Online Server → creates unsigned tx → QR → Air-gapped PC → signs → QR → Online Server → broadcast 

Why is multisig important for cold storage?

A single key is a single point of failure. Multisig (M-of-N) requires multiple signatures to withdraw funds. Multisig is 10 times more reliable than a single key. It is the security standard for large exchanges. We support Bitcoin P2SH, P2WSH, and Ethereum Gnosis Safe. HSM for exchanges (hardware security module) further protects keys. We guarantee 99.9% uptime of cold storage operations.

Bitcoin P2WSH Multisig

from bitcoin import script, transaction def create_multisig_address(public_keys: list[bytes], m: int) -> tuple[str, bytes]: redeem_script = script.multisig(m, public_keys) p2sh_address = script.p2sh_address(redeem_script) return p2sh_address, redeem_script # 2-of-3: CEO (HSM in office), CTO (HSM at home), CFO (bank vault) address, redeem_script = create_multisig_address([key1, key2, key3], m=2) 

Ethereum Gnosis Safe

import Safe from '@safe-global/protocol-kit'; async function createEnterpriseMultisig(owners, threshold) { const safeFactory = await SafeFactory.create({ ethAdapter }); const safe = await safeFactory.deploySafe({ safeAccountConfig: { owners, threshold } }); return safe.getAddress(); } 

How to access the cold wallet?

Each withdrawal follows a documented Standard Operating Procedure (SOP). We develop detailed instructions. Withdrawal steps:

1. Initiation — ticket with amount and destination, approval from a second authorized person.
2. Transaction preparation — create unsigned tx on the online machine.
3. Signing — in an isolated room, in the presence of 2 witnesses, with verification on a hardware wallet.
4. Broadcast — final address check, publish transaction, record TxHash.
5. Confirmation — wait for N confirmations, update balance, close ticket.

For large amounts (> 100 ETH), we add a time lock — a 48-hour delay to allow canceling suspicious transactions.

uint256 public constant MIN_DELAY = 48 hours; uint256 public constant MAX_WITHDRAWAL = 100 ether; function scheduleWithdrawal(address to, uint256 amount) external onlyOwner { require(amount > MAX_WITHDRAWAL ? block.timestamp + MIN_DELAY : block.timestamp, "Immediate for small amounts"); } 

Deliverables: What's Included in the Work

What is the 3-2-1 rule for key storage?

We apply the 3-2-1 rule: 3 copies, 2 different media, 1 offsite. For the exchange: 2-of-3 Gnosis Safe for ETH, 2-of-3 P2WSH for BTC. Keys with CEO, CTO, and an independent custodian (HSM). Seed phrases on metal media (Cryptosteel) — fireproof and waterproof. Encrypted copies in different jurisdictions.

Reserve structure: Hot Wallet: 5–10% (auto withdrawals) Warm Wallet: 15–20% (2-of-3 multisig) Cold Storage: 70–80% (air-gapped, manual withdrawal via SOP) 

What is Proof of Reserves?

Proof of Reserves is a public demonstration that the exchange holds the claimed assets. We implement a Merkle tree of user balances: the exchange publishes the root and on-chain balances, and each user can verify their inclusion. This increases customer trust and reduces regulatory risk. The damage from a single incident can reach $100 million — investment in cold storage pays for itself many times over. We also provide a comprehensive exchange security audit to identify vulnerabilities.

Development Timelines

Full cycle — from 2 to 3 months. Pricing is calculated individually based on complexity and number of assets. Cold storage implementation costs from $50,000 to $200,000. For example, a mid-size exchange saved over $100 million in potential losses by implementing our cold storage solution.

Our team has 10+ years of experience in blockchain security and has implemented 15+ cold storage systems for exchanges of various sizes. Cold storage is 100 times safer than a hot wallet — but it requires sound architecture and discipline. If you want to protect your exchange's assets, contact us. We will audit your current architecture and propose an optimal solution. Order a consultation to get a project assessment in 1-2 days. Receive a detailed commercial proposal tailored to your requirements.