[Privacy Feature Request] Adding Reusable Payment Addresses (RPA) for BCH in StackWallet

[CyberAshven]

StackWallet already supports CashFusion. If possible Please add RPA for Bitcoin Cash to pair with CashFusion and improve receive-side privacy. RPA uses ECDH to derive a unique one time destination for every payment from a single reusable static address. It is wallet level upgrade. RPA is conceptually similar to Silent Payments implemented by Cake Wallet but designed for reusable static addresses.

How it works

• Alice sends to Bob’s static RPA address.
• The wallet derives a one time destination using ECDH between Alice’s ephemeral key and Bob’s static public key, then sends funds there.
• Bob scans and derives the same one time destination using his private key.
• Observers only see random one time destinations, not Bob’s static address.

RPA wallet spec: https://github.com/imaginaryusername/Reusable_specs/blob/master/reusable_addresses.md