> For the complete documentation index, see [llms.txt](https://docs.mapprotocol.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.mapprotocol.io/learn/architecture/v2-tss.md).

# MAP Protocol 2.0

## Overview

Protocol 2.0 introduces TSS (Threshold Signature Scheme) based cross-chain infrastructure. It enables secure asset transfers across all chains, including Bitcoin, through decentralized threshold signatures.

## How It Works

```
Source Chain              Maintainer Network           Target Chain
     │                          │                           │
     │  1. User deposits        │                           │
     │     to Vault             │                           │
     │                          │                           │
     │  2. Maintainers          │                           │
     │     observe ────────────►│                           │
     │                          │                           │
     │                    3. TSS KeySign                    │
     │                          │                           │
     │                          │  4. Signature submitted   │
     │                          ├──────────────────────────►│
     │                          │                           │
     │                          │  5. Gateway verifies      │
     │                          │     and releases assets   │
     │                          │                           │
```

### Step-by-Step Process

1. **Deposit**: User deposits assets to Vault address on source chain
2. **Observe**: Maintainers detect and confirm the deposit
3. **Sign**: Maintainers collaboratively sign withdrawal transaction via TSS
4. **Submit**: Signature is submitted to target chain
5. **Release**: Gateway contract verifies signature and releases assets

## Key Components

### TSS (Threshold Signature Scheme)

Cryptographic technology that allows multiple parties to jointly sign without any single party holding the full key.

* **2/3 Threshold**: Requires 2/3 of Maintainers to sign
* **No Single Point of Failure**: No one can sign alone
* **Single Signature Output**: Looks like a normal signature on-chain

### Vault

TSS-controlled address that holds cross-chain assets.

* Managed by Maintainer network
* No single entity controls the funds
* Supports multiple chains including Bitcoin

### Gateway

Smart contract on each chain for signature verification.

* Verifies TSS signatures
* Executes withdrawals
* Handles TSS key updates

### Maintainer

Network participant that observes events and participates in signing.

* Must be a registered Validator
* Participates in KeyGen and KeySign
* Earns rewards for participation

## Security Model

### Threshold Security

* **2/3 Byzantine Fault Tolerance**: System remains secure with up to 1/3 malicious nodes
* **Distributed Custody**: Assets are never controlled by a single entity
* **Slashing**: Malicious behavior is penalized

### Why It's Secure

* **No Private Key Exposure**: Full key never exists in one place
* **Decentralized Signing**: Multiple independent parties required
* **Economic Security**: Maintainers stake assets at risk

## Supported Chains

* **Bitcoin**: Full support via TSS Vault
* **Ethereum & EVM Chains**: Gateway contract verification
* **Solana**: secp256k1 verification via Gateway
* **Any Chain**: Can support any chain that verifies signatures

## Advantages over v1

| Aspect          | v1 (Light Client)            | v2 (TSS)                       |
| --------------- | ---------------------------- | ------------------------------ |
| Bitcoin Support | ❌                            | ✅                              |
| Gas Cost        | Higher (proof verification)  | Lower (signature verification) |
| Implementation  | Need light client per chain  | Universal TSS                  |
| Speed           | Depends on light client sync | Fast threshold signing         |

## Fusion with Light Client

Protocol v2 can integrate light client verification for enhanced security:

* TSS provides fast finality
* Light client provides additional trustless verification
* Best of both worlds

## Use Cases

* **Bitcoin Cross-chain**: Bridge BTC to EVM chains
* **Asset Transfers**: Fast and secure token transfers
* **LP-based Liquidity**: Liquidity providers earn fees
* **Multi-chain DeFi**: Access liquidity across chains

## Getting Started

* **Become Maintainer**: See [Compass-TSS Guide](/compass-tss-crossx/overview.md)
* **Provide Liquidity**: Deposit assets to Vault
* **Use Cross-chain**: Interact with Gateway contracts

## Roles in v2

| Role        | Responsibility                      | Reward           |
| ----------- | ----------------------------------- | ---------------- |
| Validator   | Block production on MAP Relay Chain | Block rewards    |
| Maintainer  | TSS signing & observation           | Cross-chain fees |
| Relayer     | Submit signatures to target chains  | Transaction fees |
| LP Provider | Provide liquidity to Vaults         | Fee sharing      |