Overview

Design Goals and Background

MAP Protocol v2.0 is a decentralized cross-chain protocol based on TSS (Threshold Signature Scheme). The protocol enables secure cross-chain asset transfers through threshold signature technology without relying on traditional multi-sig wallets or centralized custody solutions.

Core Design Goals:

• Decentralized Security: Through TSS threshold signatures, no single node can independently control cross-chain assets

• High Fault Tolerance: The system can tolerate up to 1/3 of nodes failing or acting maliciously

• Multi-chain Support: Supports EVM-compatible chains, Bitcoin, and other heterogeneous chains

• On-chain Governance: Maintainer management and state consensus implemented through Solidity contracts on MAP Relay Chain

System Roles

Validator

• Block producers and consensus participants of MAP Relay Chain

• Responsible for validating and confirming cross-chain transactions

• Participate in network consensus by staking MAPO tokens

• Validators can register as Maintainers to participate in cross-chain signing

Maintainer

• Core participants in cross-chain signing

• Elected from registered Validators

• Responsibilities:

  • Monitor cross-chain events on source chains (Observer)

  • Participate in TSS key generation (KeyGen)

  • Participate in cross-chain transaction signing (KeySign)

  • Submit observation results to MAP Relay Chain

• Hold TSS private key shares, collectively managing Vault addresses

Relayer

• Responsible for submitting signed transactions to target chains

• Receive transaction fee subsidies and rewards

• Can be Maintainer nodes or independent service providers

• For contract chains, anyone can submit signatures to the target chain Gateway

LP Provider (Liquidity Provider)

• Provide liquidity to cross-chain pools

• Receive cross-chain fee sharing and LP incentives

• Participate by depositing assets to Vault addresses

Overall Architecture

┌─────────────────────────────────────────────────────────────────────────────┐
│                              User/DApp                                       │
└─────────────────────────────────────────────────────────────────────────────┘
                                    │
                                    ▼
┌─────────────────────────────────────────────────────────────────────────────┐
│                           Source Chain                                       │
│  ┌─────────────┐    ┌─────────────┐    ┌─────────────┐                      │
│  │  Gateway    │    │    Vault    │    │ Cross-chain │                      │
│  │  Contract   │───▶│   Address   │───▶│   Events    │                      │
│  └─────────────┘    └─────────────┘    └─────────────┘                      │
└─────────────────────────────────────────────────────────────────────────────┘
                                    │
                                    │ Observer Monitoring
                                    ▼
┌─────────────────────────────────────────────────────────────────────────────┐
│                        Maintainer Network                                    │
│  ┌─────────────┐    ┌─────────────┐    ┌─────────────┐    ┌─────────────┐   │
│  │ Maintainer  │    │ Maintainer  │    │ Maintainer  │    │ Maintainer  │   │
│  │     A       │◀──▶│     B       │◀──▶│     C       │◀──▶│     D       │   │
│  └─────────────┘    └─────────────┘    └─────────────┘    └─────────────┘   │
│         │                  │                  │                  │          │
│         └──────────────────┴──────────────────┴──────────────────┘          │
│                                    │                                         │
│                           P2P Network Communication                          │
│                           TSS KeyGen / KeySign                               │
└─────────────────────────────────────────────────────────────────────────────┘
                                    │
                                    │ Submit Observations/Votes
                                    ▼
┌─────────────────────────────────────────────────────────────────────────────┐
│                           MAP Relay Chain                                    │
│                                                                              │
│  ┌──────────────────┐    ┌──────────────────┐    ┌──────────────────┐       │
│  │   Maintainer     │    │   TSS            │    │   Relay          │       │
│  │   Manager        │    │   Manager        │    │                  │       │
│  │ Register/Elect/  │    │ TSS Generation/  │    │ Cross-chain      │       │
│  │ Incentive/Slash  │    │ Switching        │    │ Flow Management  │       │
│  └──────────────────┘    └──────────────────┘    └──────────────────┘       │
│                                                                              │
│  ┌──────────────────┐    ┌──────────────────┐    ┌──────────────────┐       │
│  │   Vault          │    │   Registry       │    │   Gas            │       │
│  │   Manager        │    │                  │    │   Service        │       │
│  │ State Transition/│    │ Chain/Token/     │    │ Fee Recording/   │       │
│  │ Asset Recording  │    │ Alias Registry   │    │ Updating         │       │
│  └──────────────────┘    └──────────────────┘    └──────────────────┘       │
│                                                                              │
└─────────────────────────────────────────────────────────────────────────────┘
                                    │
                 ┌──────────────────┴──────────────────┐
                 │                                     │
                 ▼                                     ▼
┌────────────────────────────────┐    ┌────────────────────────────────┐
│   Contract Chains (EVM/Solana) │    │  Non-contract Chains (Bitcoin) │
│                                │    │                                │
│  TSS signature submitted to    │    │  TSS builds and signs tx       │
│  Relay Chain                   │    │         │                      │
│         │                      │    │         ▼                      │
│         ▼                      │    │  Broadcast to target chain     │
│  Relayer/Anyone submits sig    │    │         │                      │
│         │                      │    │         ▼                      │
│         ▼                      │    │  ┌─────────────┐               │
│  ┌─────────────┐               │    │  │   Vault     │               │
│  │  Gateway    │               │    │  │   Address   │               │
│  │  Verify sig │               │    │  │   (TSS)     │               │
│  │  Execute    │               │    │  └─────────────┘               │
│  │  TSS Switch │               │    │                                │
│  └─────────────┘               │    │                                │
└────────────────────────────────┘    └────────────────────────────────┘

Core Components

On-chain Components

MAP Relay Chain Contracts:

Component	Function
Maintainer Manager	Maintainer registration, updates, election, and incentive/slashing
TSS Manager	Manage TSS generation and switching processes
Relay	Manage cross-chain flow on Relay Chain
Vault Manager	Vault state transitions and asset recording per chain
Registry	Register and manage supported chains, tokens, and aliases
Gas Service	Record and update fee information for each chain

Other Chain Contracts:

Component	Function
Gateway	Receive/send cross-chain assets, verify TSS signatures, complete TSS switching

Off-chain Components (Maintainer Nodes)

Component	Function
Observer	Monitor cross-chain events on each chain, parse and submit to MAP Relay Chain
Signer	Participate in TSS KeyGen and KeySign processes
P2P Network	Communication network between Maintainer nodes
Local Storage	Local storage for key shares, pending transactions, etc.

Vault State Model

Vault is an address managed by TSS, used to custody cross-chain assets. Each Vault has the following states:

┌──────────┐    Election Complete   ┌──────────┐    New Vault Activated  ┌──────────┐
│  Pending │ ─────────────────────▶ │  Active  │ ─────────────────────▶  │ Retiring │
│          │                        │          │                         │          │
└──────────┘                        └──────────┘                         └──────────┘
                                                                               │
                                                                               │ Asset Migration Complete
                                                                               ▼
                                                                         ┌──────────┐
                                                                         │ Retired  │
                                                                         │          │
                                                                         └──────────┘

State	Description
Active	Currently active Vault, receives new cross-chain deposits
Retiring	Vault being migrated, no longer receives new deposits, waiting for asset migration to complete
Retired	Vault with completed asset migration, no longer in use

Notes:

• If users mistakenly transfer assets to a Retired Vault and the corresponding TSS nodes are still running, the system will automatically refund the assets to the user

• The system synchronizes all Vaults in Active and Retiring states

• Also synchronizes Retired Vaults generated within a certain number of recent blocks (for handling delayed transaction confirmations and refunds)

TSS Threshold Signature

MAP Protocol v2.0 uses TSS (Threshold Signature Scheme) for decentralized asset custody.

Basic Principles:

• Private keys are split into multiple shares distributed across different Maintainer nodes

• Signing requires at least 2/3 of nodes to collaborate

• No single node can independently generate a valid signature

Key Processes:

Process	Description
KeyGen	Key generation, after election, new Maintainer set collaboratively generates new Vault public key
KeySign	Transaction signing, Vault Maintainer members collaborate to generate transaction signature

Supported Signature Algorithms:

Algorithm	Use Cases
secp256k1	Bitcoin, EVM-compatible chains, and other chains supporting secp256k1

Handling Chains Not Natively Supporting secp256k1:

• For chains like Solana using ed25519, verification is completed by verifying secp256k1 signatures through on-chain contracts

• Gateway contracts are responsible for verifying TSS signature validity

Glossary

Term	Description
TSS	Threshold Signature Scheme
Maintainer	Core participant in cross-chain signing
Validator	Validator of MAP Relay Chain
Vault	Cross-chain asset custody address managed by TSS
KeyGen	TSS key generation process
KeySign	TSS transaction signing process
Churn	TSS switching/rotation process
Observer	Module that monitors cross-chain events on each chain
Gateway	Cross-chain contract on other chains
Epoch	Period of MAP Relay Chain
Slash Point	Penalty points
Jail Epoch	Imprisonment period count
TxIn	Inbound transaction (Source Chain → Relay Chain)
TxOut	Outbound transaction (Relay Chain → Target Chain)
Memo	Cross-chain information field for non-contract chains