# Overview

## What is Armchain?

Armchain is a **quantum-resistant** Layer 1 blockchain. Think of it as an Ethereum-compatible chain that swaps out the traditional signature scheme (ECDSA) for a quantum-safe one (**ML-DSA44**, standardized by NIST in FIPS 204). This means your smart contracts, tokens, and dApps get the same developer experience you're used to, but with cryptography designed to withstand future quantum computers.

Armchain uses the **Lachesis aBFT** consensus protocol for **instant finality**. Once a transaction is confirmed, it's permanent with no chance of rollbacks or reorganizations. The network maintains full **EVM compatibility** (London fork), so standard Solidity contracts deploy without any changes.

## Why Armchain?

### The Quantum Threat: Why It Matters

Current blockchain networks (Ethereum, Bitcoin, etc.) rely on ECDSA signatures based on the secp256k1 elliptic curve. A sufficiently powerful quantum computer running Shor's algorithm could break these signatures, which would mean:

* **Signature forgery**: Attackers could authorize transactions from any address
* **Private key recovery**: On-chain public keys could be used to derive private keys
* **Consensus takeover**: Validator authentication could be compromised

While large-scale quantum computers don't exist yet, the "harvest now, decrypt later" threat is real today. Adversaries can store signed blockchain data now and attempt to crack it later when quantum hardware matures.

### How Armchain Addresses This

Armchain uses post-quantum cryptography at every layer of the protocol:

| Layer                     | Classical (Ethereum)     | Armchain (Post-Quantum)                 |
| ------------------------- | ------------------------ | --------------------------------------- |
| **User Transactions**     | ECDSA (secp256k1)        | ML-DSA44 (FIPS 204)                     |
| **Validator Signatures**  | ECDSA                    | ML-DSA44                                |
| **Wallet Key Derivation** | BIP-32/44 with secp256k1 | BIP-32/44 with ML-DSA44 (hardened only) |
| **Address Format**        | keccak256(ECDSA pubkey)  | keccak256(ML-DSA44 pubkey)              |
| **Transaction Type**      | Type 0/1/2               | Type 3 (PQC)                            |

### Instant Finality

Unlike Ethereum where you might wait several minutes for full finality, Armchain's Lachesis aBFT consensus provides **deterministic, immediate finality**:

* **No rollbacks**: Confirmed transactions are irreversibly final
* **Asynchronous**: No synchronous rounds or timeouts
* **Byzantine fault tolerant**: Tolerates up to 1/3 malicious validators
* **DAG-based**: Parallel event processing via a directed acyclic graph

### EVM Compatibility

If you've built on Ethereum, you can build on Armchain. The network runs a full Ethereum Virtual Machine (London fork):

* Standard **Solidity** contracts deploy without modification
* **Remix IDE** for development and deployment
* **Hardhat** for compilation and project structure (signing requires the Armchain Ethers SDK)
* **Armchain Ethers SDK** (`@armchain-ethersv6/ethers`) for dApp development
* Standard **JSON-RPC** APIs (`eth_sendTransaction`, `eth_call`, etc.)
* **ERC-20**, **ERC-721**, **ERC-1155** token standards
* EIP-1559 gas pricing and EIP-2930 access lists

## Architecture at a Glance

Here's how the different layers of Armchain fit together:

| Layer                       | Components                                          |
| --------------------------- | --------------------------------------------------- |
| **Applications**            | dApps, Wallets, Smart Contracts                     |
| **JSON-RPC API**            | `eth`, `arm`, `dag`, `admin`, `personal` namespaces |
| **EVM**                     | Ethereum Virtual Machine (London fork rules)        |
| **Transaction Processing**  | Type 3 PQC transactions, EIP-1559 gas               |
| **Lachesis aBFT Consensus** | DAG ordering, event emission, instant finality      |
| **ML-DSA44 Cryptography**   | Signatures, key management, validation              |
| **P2P Network**             | devp2p, gossip protocol, peer discovery             |

## Armchain vs. Other Chains

| Feature        | Armchain      | Ethereum     | Polygon PoS  | Arbitrum          |
| -------------- | ------------- | ------------ | ------------ | ----------------- |
| Consensus      | Lachesis aBFT | Gasper (PoS) | pBFT + PoS   | Optimistic Rollup |
| Finality       | Instant       | \~15 min     | \~2 min      | \~7 days (L1)     |
| Quantum Safe   | ✅ ML-DSA44    | ❌ ECDSA      | ❌ ECDSA      | ❌ ECDSA           |
| EVM Compatible | ✅             | ✅ (native)   | ✅            | ✅                 |
| Layer          | L1            | L1           | L1 sidechain | L2                |
| Native Token   | ARM           | ETH          | POL          | ETH               |

## Who is This Documentation For?

Whether you're an experienced blockchain developer or just getting started, you'll find guides tailored to your role:

* **dApp Developers**: Smart contract deployment and interaction
* **SDK/Library Authors**: Integrating post-quantum signing into tooling
* **Node Operators**: Running full/archive nodes and validators
* **Wallet Developers**: Implementing quantum-safe key management
* **Researchers**: Post-quantum blockchain architecture

## Next Steps

* [Quickstart →](/get-started/quickstart.md) Deploy your first contract in 10 minutes
* [Network Configuration →](/get-started/network-configuration.md) Connect your tools and wallet to Armchain
* [Architecture Deep Dive →](/architecture/consensus.md) Learn how Armchain works under the hood


---

# Agent Instructions: 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:

```
GET https://docs.armchain.org/get-started/overview.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
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.