Contributing to Lightning Network: Building a Secure Preimage RPC for LND

Contributing to core infrastructure like lnd (Lightning Network Daemon) is a great way to understand the protocol deeply. Recently, I implemented a new RPC method called GeneratePreimage to solve a common developer friction point. The Problem: To create secure Hold Invoices, developers need a 32-byte preimage and its SHA-256 hash. LND didn't have a native way to generate these, forcing developers to roll their own crypto logic on the client side—which can lead to security risks if weak entropy is used. The Solution: I implemented a stateless RPC that uses Go's crypto/rand to generate secure preimages. It returns both the preimage and the hash without modifying the database. Implementation Details: I defined the API contract in Protobuf and implemented the handler in Go. Here is the core logic I added to rpcserver.go: func (r *rpcServer) GeneratePreimage(ctx context.Context, req *lnrpc.GeneratePreimageRequest) (*lnrpc.GeneratePreimageResponse, error) { var preimage lntypes.Preimage // 1