State Transition Proof

Background

Evolution of Security

In early versions of Agglayer, the system focused on securing cross-chain transactions through a single verification method. While this worked for basic operations, it didn't verify whether individual chains themselves were operating correctly.

The Challenge: Like having a security guard only checking IDs at a building entrance, but not verifying if the building's internal systems are functioning properly.

The Solution: Agglayer v0.3 introduces a comprehensive dual proof system - like having both a building security system and a security guard working together.

Overview

State Transition Proof is a comprehensive trust validation process that ensures the security and validity of all operations in Agglayer through two distinct verification systems:

Dual Proof System:

• Internal Chain Validation: State transition verification within individual chains
• Cross-Chain Validation: Bridge operation verification between chains (Aggchain Proof + Pessimistic Proof)

Figure 1: High-level overview of the v0.3 dual proof system

What You Can Do

• Verify Chain Operations: Ensure internal chain state transitions are mathematically correct
• Validate Cross-Chain Transfers: Verify that asset transfers between chains are secure and atomic
• Support Multiple Chain Types: Enable different consensus mechanisms while maintaining security
• Flexible Integration: Choose between ECDSA signatures or advanced validity proofs

How It Works

The State Transition Proof system implements a two-step verification process that validates both internal chain operations and cross-chain transfers:

graph TD
    subgraph Internal ["Internal Chain Validation"]
        A[State Transition Verification]
        B[Validity Proof / ECDSA Signature]
    end
    
    subgraph CrossChain ["Cross-Chain Validation"]
        C[Aggchain Proof]
        D[Pessimistic Proof]
    end
    
    A --> B
    B --> C
    C --> D
    
    style Internal fill:#e8f5e8
    style CrossChain fill:#e3f2fd

Security Model:

• Internal validation verifies that chains are operating correctly internally
• Cross-chain validation verifies that bridge operations are secure and atomic
• Dual proof system ensures comprehensive security coverage

Core Concepts

Understand the dual proof system architecture: