@ABLA 11 November 2025

Silent RPA (SRPA): A New Privacy Framework for Stealth Addresses on Bitcoin Cash

**Silent RPA (SRPA) is the next-generation privacy framework for Bitcoin Cash that unifies Silent Payments (BIP352) and Reusable Payment Codes (BIP47).** The goal is simple yet powerful: A single reusable BCH address that can privately receive both coins and tokens — with no notification transactions, no metadata leaks, and no new wallet type. **🔒 What SRPA Enables** - Hidden sender and receiver identities via ECDH one-time derivations - Full CashAddr and CashTokens compatibility - Seamless integration with CashFusion for stronger privacy - Full on-chain verifiability without breaking existing wallet standards The vision: Make Bitcoin Cash payments as private and simple as handing over physical cash — while staying fully interoperable with today’s BCH ecosystem. **⚙️ Phase 1 – Proof of Concept ✅** Phase 1 is complete and demonstrates a working prototype: - Alice can fund Bob privately using a covenant - Only Bob can redeem the funds everything verifiable on-chain - Sigma proofs and Pedersen binding hide proof data - Encrypted OP_RETURN payloads contain no identifiable metadata Proof of Work: - Alice’s covenant locking UTXOs for Bob: https://2026-tempnet. chaingraph. cash/tx/c0f59b851e1840e998c9482206c8a9d1ab03d7d3e6b1a55b0ec17a3ec9e739aa - Bob spending the locked UTXOs: https://2026-tempnet. chaingraph. cash/tx/4146935ef1b76d25a75df7ed601a0919b1696eb31ac50b26924b49c747f7134b A runnable demo (node dist/demo.js) shows how stealth addresses are derived, covenants enforce proof validity, and CashTokens integrate directly. **🚨 Phase 2 – Beaconless Output Binding 🔥 (Main Funding Goal)** Phase 2 takes SRPA to its full potential with true cash-like privacy on BCH: - No OP_RETURN beacons – zero visible metadata - Fully shielded sender, receiver, and amount - Output-fingerprint verification to bind off-chain proofs to real outputs - Compact transactions (≤ 100 KB target) - Integration with 2026 VM improvements for native zero-knowledge support The result: Standard-looking transactions, total privacy, and complete compatibility a major leap forward for Bitcoin Cash privacy and usability. **💰 Support the Development** Bastian is raising funds to: - Finalize Phase 1 documentation and demo code - Begin implementing Phase 2 (Beaconless Output Binding) - All work is open-source, BCH-native, and focused on real wallet integration. Support the campaigns: Phase 1 Finishing – FundMe: https://fundme. cash/campaign/79 Phase 2 Kick-off – FundMe: https://fundme. cash/campaign/80 **🌐 Why It Matters** SRPA represents the next evolution after CashFusion and CashTokens - a unified, private, and practical address system for Bitcoin Cash. Support Bastian’s work and help BCH take the final step toward true cash-like privacy 💚