ELIP: Silent Payments with Confidential Transactions on Liquid

[Ferryx349]

Summary

This ELIP specifies Confidential Silent Payments on Liquid, BIP-352's unlinkable static addresses combined with CT's hidden amounts and assets.

The BIP-352 core (input aggregation, shared secret, partial tweaks, labels, K_max) is imported without modification. Liquid-specific additions are the CT envelope: confidential P2WPKH outputs, per-output blinding keys derived from S in a separate hash domain, lsp/tlsp addresses (distinct from lq CT addresses), an elsp descriptor, optional PSET fields, normative scan/recovery procedures, and a tweak-server receive profile with a concrete REST API.

Includes worked test vectors. No consensus or relay changes.

Highlights vs. a minimal adaptation

• Dedicated lsp/tlsp HRP:- avoids collision with existing confidential addresses
• Full scanning algorithm:- derivation index k, label handling, BIP-352 increment rules
• Two receive paths:- full-node scan and untrusted tweak-server (BIP-352 index server model)
• Correct BIP-32 paths:- m/352'/coin'/account'/1'/0 (scan), .../0'/0 (spend)
• Recovery and wallet state:- what must be backed up beyond the seed

Status

Draft. Reference implementation (LWK) and final lsp1... test vector pending.

[apoelstra]

Appears to be slop. Blocked from org.