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

# Introduction

Welcome to the official documentation for **AstralBeam** - a secure, bidirectional bridge between **Casper Network** and **EVM-compatible chains**.

## What is AstralBeam?

AstralBeam enables token transfers between Casper Network and configured EVM chains. Ethereum, Base, Polygon, and Robinhood Chain testnet routes are active; Arbitrum and BNB are coming soon. Robinhood Chain mainnet is configured but intentionally undeployed. The Robinhood testnet V16 locker, TEST mapping, and finalized-mode round trip are verified on-chain. The bridge uses a **consensus-aware security model** combining M-of-N multi-signature attestation with cryptographic proof verification.

### Key Features

* **Multi-Chain Support** - Bridge tokens to and from multiple EVM chains
* **Consensus-Aware Security** - Block headers stored on-chain with receipts roots for verification
* **MPT Proof Verification** - Each relayer independently verifies Merkle Patricia Trie proofs before signing
* **M-of-N Multi-Sig** - Requires 3-of-5 independent relayers to authorize any transfer
* **Non-Custodial** - Your tokens remain under your control until transfer initiation
* **Finality Protection** - EVM→Casper processing uses each chain's protocol `finalized` tag plus a chain-specific confirmation-depth floor; Casper finality is handled separately

## Security Model

AstralBeam implements a **consensus-aware, proof-verified security model**:

```mermaid
flowchart TB
    subgraph EVM[EVM Chain]
        Lock[Lock Event in Block N]
        Receipt[Transaction Receipt]
        Root[Receipts Root]
    end

    subgraph Verification[Independent Verification]
        R1[Relayer 1 - Verifies MPT Proof]
        R2[Relayer 2 - Verifies MPT Proof]
        R3[Relayer 3 - Verifies MPT Proof]
        R4[Relayer 4]
        R5[Relayer 5]
    end

    subgraph Casper[Casper Network]
        EthClient[EthClient - Stores Block Headers]
        TokenFactory[TokenFactory - Mints Tokens]
    end

    Lock --> Receipt
    Receipt --> Root
    Root --> R1 & R2 & R3
    R1 & R2 & R3 -->|3-of-5 Signatures| TokenFactory
    EthClient -->|Validates receipts root| TokenFactory
```

**How It Works:**

1. **Event Detection** - Relayers monitor EVM chains for Lock/Burn events
2. **Block Finality** - Require both protocol-native EVM finality and the configured secondary depth floor (fail closed if the tag is unavailable)
3. **MPT Proof Verification** - Each relayer independently verifies cryptographically that the event exists in the block's receipts trie
4. **Attestation Signing** - Relayers sign attestation hashes that include chain ID (replay protection)
5. **On-Chain Validation** - Casper's EthClient stores block headers; TokenFactory verifies receipts root matches
6. **Threshold Execution** - With 3-of-5 valid signatures, tokens are minted/unlocked

## Supported Token Types

| Direction    | Source         | Destination    | Process                               |
| ------------ | -------------- | -------------- | ------------------------------------- |
| EVM → Casper | ERC-20         | CEP-18         | Lock on EVM, mint on Casper           |
| Casper → EVM | CEP-18         | ERC-20         | Burn on Casper, unlock on EVM         |
| Casper → EVM | Native CEP-18  | Wrapped ERC-20 | Lock on Casper, mint wrapped on EVM   |
| EVM → Casper | Wrapped ERC-20 | Native CEP-18  | Burn wrapped on EVM, unlock on Casper |

## Architecture Overview

```mermaid
flowchart LR
    subgraph EVM[EVM Chains]
        Locker[MultiSig ERC20Locker]
        Wrapped[Wrapped Tokens]
    end

    subgraph Relayers[Relayer Network M-of-N]
        direction TB
        P2P[P2P Network HTTPS/TLS]
        Verify[MPT Verification]
        Sign[Signature Collection]
    end

    subgraph Casper[Casper Network]
        Factory[Token Factory]
        EthClient[EthClient Headers]
        CEP18[Bridged CEP-18]
    end

    Locker <--> Relayers
    Wrapped <--> Relayers
    Relayers <--> Factory
    Relayers --> EthClient
    Factory <--> CEP18
    EthClient --> Factory
```

## Quick Links

### For Users

* [Getting Started](/getting-started/user-guide.md) - Connect your wallets and bridge tokens
* [Supported Tokens](/using-astralbeam/supported-tokens.md) - List of bridgeable tokens
* [Troubleshooting](/using-astralbeam/troubleshooting.md) - Common issues and solutions

### For Developers

* [API Reference](/api-reference/api-reference.md) - REST API documentation
* [Smart Contracts](/smart-contracts/contracts.md) - Contract interfaces and addresses
* [Developer Guide](/for-developers/developer-guide.md) - Integration examples

### For Operators

* [Operator Guide](/operators/operator-guide.md) - Deploy and run bridge relayers
* [CLI Reference](/operators/cli-reference.md) - Command-line tool documentation
* [Monitoring](/operators/monitoring.md) - Grafana dashboards and alerts

## Current Networks

### Testnet (Active)

| Network                 | Chain ID | Status                                          |
| ----------------------- | -------- | ----------------------------------------------- |
| Casper Testnet          | -        | **Active**                                      |
| Ethereum Sepolia        | 11155111 | **Active**                                      |
| Base Sepolia            | 84532    | **Active**                                      |
| Polygon Amoy            | 80002    | **Active**                                      |
| Arbitrum Sepolia        | 421614   | Coming Soon                                     |
| BNB Smart Chain Testnet | 97       | Coming Soon                                     |
| Robinhood Chain Testnet | 46630    | **Active; finalized-mode round trip certified** |

### Mainnet (Coming Soon)

Mainnet deployment is planned after thorough testnet validation. Robinhood Chain mainnet (`4663`, measured \~0.1s blocks) is configured for protocol `finalized` mode with a 15,000-block floor, but its locker is intentionally undeployed and the route is disabled pending separate approval. Robinhood Chain Testnet (`46630`, measured \~0.4s blocks) uses a 6,000-block floor. Its V16 locker, TEST mapping, and finalized-mode round trip are verified, and the testnet route is enabled.

## Bridge Interface

Access the bridge at: [**https://astralbeam.io**](https://astralbeam.io)

## Getting Help

* **Issues**: [GitHub Issues](https://github.com/make-software/cspr-bridge/issues)
* **X**: [@AstralBeam\_io](https://x.com/AstralBeam_io)
* **Telegram**: [t.me/astralbeam\_io](https://t.me/astralbeam_io)

## License

This project is licensed under the MIT License.


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter:

```
GET https://docs.astralbeam.io/getting-started/readme.md?ask=<question>&goal=<endgoal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.

The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.