Overview
**Enable offline QR-code–based cryptocurrency payments** with periodic synchronization to the Bisq network. Users initialize their wallet online once to load balances and keys, then conduct payments offline and sync every **1 minute/1 hour/1 day/1 week**.
## 
Technical Architecture and Workflow
First-Time Initialization
1. User opens the Bisq wallet in an online environment.
2. Wallet performs a secure handshake with the Bisq network, downloading and verifying the user’s balance and key status.
3. Public/private keys, current balance, and anti-replay nonces are encrypted and stored in the device’s secure enclave.
Offline QR-Code Payment
1. Payer scans the payee’s QR code (containing address, amount, and nonce) on their offline device.
2. Device signs the transaction internally using the private key, updates the local balance, and adds the transaction to an “offline pool.”
3. Wallet displays a **payment success** confirmation.
Periodic On-Chain Synchronization
• Sync intervals: **1 minute, 1 hour, 1 day, 1 week**
• Batch submission includes:
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Signed transactions
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Sequential nonce checks
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Merkle root for batch integrity
• Off-chain aggregation reduces on-chain fees by submitting a single aggregated transaction for multiple offline payments.
## 
Security Measures
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Key Management and Signing
- Private keys are stored in a hardware security module (Secure Enclave or TEE).
- All signing occurs locally; keys never leave the device.
### 
Anti-Replay Protection
- Each offline payment carries a unique, incrementing nonce.
- The Bisq network verifies nonce continuity upon sync to prevent replay attacks.
### 
Data Encryption and Integrity
- Offline transaction pool is encrypted with AES-256-GCM.
- Wallet verifies file integrity and signatures before synchronization.
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Legal and Compliance Advantages
**Bypass real-time network restrictions:** Offline payments function in areas with internet blocks or crypto bans.
**Reduce fiat exchange risk:** Users trade Bisq directly P2P; businesses pay salaries in Bisq without converting back to fiat.
**Auditability:** Periodic on-chain sync ensures all transactions are traceable, supporting KYC/AML compliance.
## 
Use Cases and Deployment
1. **Cross-Border Trade:** Merchants settle payments offline and sync later in bulk.
2. **Remote Regions:** Transactions succeed without reliable network coverage.
3. **Payroll Distribution:** Companies disburse salaries in Bisq; employees spend offline or withdraw later.
**Exchange Rate Parity:** Wallets can peg Bisq to Bitcoin or fiat rates in real time, ensuring stable value.