Introduction

Introduction to SIP Protocol

SIP (Shielded Intents Protocol) is a privacy layer for cross-chain transactions that integrates with NEAR Intents to provide configurable transaction privacy.

The Problem

Cross-chain transactions have become fundamental to decentralized finance, yet they consistently leak sensitive information:

• Sender addresses are publicly visible
• Transaction amounts can be traced
• Recipient identities are linkable across chains

Even when using privacy-preserving systems like Zcash, interacting with transparent blockchains through address reuse destroys privacy guarantees.

The Transparency Vulnerability

Consider a user with shielded ZEC wanting to swap to SOL:

1. User has: shielded ZEC in z-address (private)
2. User initiates: ZEC → SOL swap via intent
3. Swap completes: SOL sent to user's Solana address
4. Refund: sent to t1ABC... (transparent, reused)

Problem: t1ABC is reused across transactions
Chain analysis: "t1ABC received refunds 50 times"
              → Links to user's shielded activity
              → Compromises entire privacy set

The Solution

SIP addresses these challenges through three complementary cryptographic techniques:

1. Pedersen Commitments

Hide transaction amounts while enabling verification:

const { commitment, blinding } = commit(1000n)
// Observer sees: 0x7a3f...9c2d (meaningless curve point)
// You know: the commitment hides 1000

2. Stealth Addresses

Generate unique, one-time recipient addresses:

const { stealthAddress } = generateStealthAddress(recipientMetaAddress)
// Each transaction → fresh unlinkable address
// No address reuse → no linkability

3. Viewing Keys

Enable selective disclosure for compliance:

const viewingKey = generateViewingKey('/audit/2024')
// Auditor can decrypt: sender, amount, recipient
// Public sees: cryptographic commitments only

Why SIP?

Feature	Without SIP	With SIP
Sender	0xABC…123 (known)	Commitment (hidden)
Amount	1000 ETH	Commitment (hidden)
Recipient	0xDEF…456	Stealth address (unlinkable)
Compliance	Trivial analysis	Viewing key required

Application Layer Design

SIP operates as an application layer atop existing infrastructure:

• No protocol changes required to underlying blockchains
• Integrates with NEAR Intents settlement system
• Compatible with existing wallets via wallet adapters
• Sub-30ms overhead for privacy operations

Privacy Levels

Choose the right level for your use case:

• TRANSPARENT: Standard swap, no privacy, maximum compatibility
• SHIELDED: Full privacy, hidden sender/amount/recipient
• COMPLIANT: Full privacy + selective disclosure via viewing keys

Getting Started

Ready to add privacy to your cross-chain transactions?

1. Quick Start Guide - Install and use the SDK
2. Architecture - Understand the system design
3. Privacy Levels - Choose the right privacy level