XSTRP — XRP Safe Transfer & Recovery Protocol

This repository contains the reference Rust implementation of the XRP Safe Transfer & Recovery Protocol (XSTRP).

XSTRP is a safety-first transfer protocol designed to guarantee that funds are never stranded, never misdirected, and never released without explicit receiver participation, even under adversarial or failure conditions.

---

Status

• RFC-XSTRP-0001 frozen (v1.0)
• Core protocol state machine complete and locked for v1
• Reference implementation written in Rust
• Explicit safety-first design with terminal-state immutability
• No XRPL integration yet
• No cryptography yet
• Protocol logic formally verified via TLA+ (Phase C5)
• Audit-ready (no external audit performed)

---

Protocol State Machine (v1)

States

• Created
• Committed
• Completed (terminal)
• Expired
• Refunded (terminal)
• Invalid (terminal)

Events

• ReceiverConfirms
• CompletionProofVerified
• ProofInvalid
• Timeout
• RefundProcessed
• InvalidDetected

Guarantees

• Terminal states are immutable
• Invalidity can be detected and enforced from any non-terminal state
• No legal execution path results in unrecoverable or stranded funds
• All transitions are explicit and exhaustively checked

---

Implementation Status

• Core state machine implemented in src/state_machine.rs
• All legal and illegal transitions explicitly handled
• Unit-tested invariants
• cargo test passes cleanly

---

Testing

The reference implementation includes unit tests validating:

• Successful commit and completion paths
• Invalid-proof handling
• Global invalidation handling
• Terminal-state immutability

---

Milestone Declaration

The v1 core state machine is complete and frozen.

Further work will proceed only by extension, not modification, and will focus on:

• XRPL integration
• Proof format definition
• Cryptographic verification
• Ledger interaction modeling

---

License

Payne Protocol License (PPL-0.1) — see the LICENSE file for full terms.