Paper 2026/602

Confidential Transfers for Multi-Purpose Tokens on the XRP Ledger

Abstract

We introduce Confidential Transfers for Multi-Purpose Tokens (Confidential MPTs) on the XRP Ledger, a cryptographic extension of the XLS-33 token standard that enables confidential balances and hidden transfer amounts while preserving public supply verifiability. The protocol replaces plaintext per-account balances with EC–ElGamal ciphertexts and employs non-interactive zero-knowledge proofs to enforce transfer correctness, balance sufficiency, and the invariant OutstandingAmount ≤ MaxAmount without requiring decryption by validators. Confidentiality is scoped to transaction amounts and account balances; sender and receiver identities remain public, preserving XRPL’s account-based execution model. Our design maintains full compatibility with existing MPT semantics: public and confidential balances coexist, issuance rules remain unchanged, and theissuer’s designated second account is treated identically to other holders. The protocol further supports issuer-controlled operations, including freeze and clawback, without weakening supply soundness. To accommodate regulatory and institutional requirements, Confidential MPTs provide cryptographic auditability through an on-chain selective-disclosure model based on multi-ciphertext balance representations and equality proofs, while remaining compatible with simpler issuer-mediated audit models. We present a complete protocol specification, a security analysis under standard discrete-logarithm assumptions, and an open-source reference implementation (mpt-crypto) that realizes the required cryptographic primitives. Experimental evaluation demonstrates that confidential transfers can be verified within XRPL validator performance constraints, with proof sizes and verification costs suitable for production deployment.

Note: Reference implementation available at https://github.com/XRPLF/mpt-crypto