> 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/reference/glossary.md). # Glossary Key terms and concepts used in AstralBeam documentation. *** ## A ### Account Hash A Casper-specific identifier derived from a public key. Format: `account-hash-abc123...`. Used for identifying accounts on Casper Network. ### Attestation A signed statement by relayers confirming an event occurred on the source chain. Contains event details and cryptographic signatures. *** ## B ### Block Finality The point at which a block is considered irreversible. AstralBeam waits for finality before processing bridge transactions: * Ethereum: 64 blocks (\~13 minutes) * EVM chains: protocol `finalized` tag plus a chain-specific confirmation-depth floor * Robinhood Chain: 15,000-block floor on mainnet and 6,000 on testnet, in addition to `finalized` * Casper: handled by Casper's instant-finality model ### Bridge Fee A small fee charged for bridge transactions to cover operational costs. Paid in native currency (ETH on EVM chains, CSPR on Casper). ### Bridged Token A token that has been transferred across chains. On the destination chain, it exists as a wrapped representation of the original token. ### Burn The process of destroying tokens on the destination chain to unlock equivalent tokens on the source chain (for return trips). *** ## C ### Casper Network A Layer 1 proof-of-stake blockchain using the Zug consensus protocol. The destination chain for EVM-to-Casper bridges. ### CEP-18 The Casper equivalent of ERC-20. A fungible token standard on Casper Network. All bridged ERC-20 tokens are represented as CEP-18 tokens on Casper. ### Chain ID A unique numeric identifier for each blockchain network: * Ethereum Mainnet: 1 * Sepolia (Testnet): 11155111 * Base Sepolia: 84532 * Arbitrum Sepolia: 421614 * Robinhood Chain: 4663 * Robinhood Chain Testnet: 46630 ### Contract Hash A Casper-specific identifier for smart contracts. Format: `hash-abc123...`. Used to call contract methods. *** ## D ### Deploy In Casper terminology, a deploy is equivalent to a transaction. It's the unit of execution on Casper Network. *** ## E ### ERC-20 The standard interface for fungible tokens on Ethereum and EVM-compatible chains. Defines methods like `transfer`, `approve`, and `balanceOf`. ### EthClient A AstralBeam contract on Casper that stores and verifies EVM block headers. Used to validate cross-chain proofs. ### Event Key A unique identifier for bridge events, derived from chain ID, block number, transaction index, and log index. Used for replay protection. ### EVM Ethereum Virtual Machine. The execution environment for smart contracts on Ethereum and compatible chains (Base, Arbitrum, etc.). *** ## F ### Finality See [Block Finality](#block-finality). *** ## G ### Gas The unit measuring computational work on EVM chains. Users pay gas fees in the chain's native currency. *** ## L ### Light Client A blockchain client that verifies block headers and canonical-chain consensus without storing the full chain. AstralBeam's Casper `EthClient` is **not** a light client; it does not perform that consensus verification. ### Signed Header Registry The Casper `EthClient` registry that stores EVM block hashes and state/receipt roots after authorization by M-of-N relayers. Honest relayers independently verify source-chain blocks and receipt proofs before signing. The registry does not itself verify EVM consensus, parent linkage, or canonical-chain membership. ### Lock The process of depositing tokens into the bridge contract on the source chain. Locked tokens are held until unlocked via a return bridge. *** ## M ### Merkle Patricia Trie (MPT) The data structure used by Ethereum to store state and transaction receipts. AstralBeam uses MPT proofs to verify events. ### Mint The process of creating new wrapped tokens on the destination chain, equivalent to locked tokens on the source chain. ### Motes The smallest unit of CSPR (Casper's native currency). 1 CSPR = 1,000,000,000 motes. ### Multi-Signature (Multi-Sig) A security mechanism requiring multiple parties to sign a transaction. AstralBeam uses 3-of-5 multi-sig attestation. ### MultiSigERC20Locker The main AstralBeam contract on EVM chains. Handles locking, unlocking, minting, and burning of tokens. *** ## N ### Native Token The primary currency of a blockchain (ETH on Ethereum, CSPR on Casper). Distinguished from tokens deployed via smart contracts. ### Nonce A sequential number ensuring uniqueness of transactions. Used for replay protection in bridge attestations. *** ## O ### Odra A smart contract framework for Casper Network. AstralBeam Casper contracts are built with Odra. *** ## P ### P2P (Peer-to-Peer) The network protocol relayers use to communicate and share attestations. Uses HTTP/HTTPS with TLS encryption for secure peer communication. ### Proof Cryptographic evidence that an event occurred. AstralBeam uses MPT proofs for receipt verification. ### Public Key A cryptographic key used to identify accounts: * EVM: 20-byte address (e.g., `0x1234...`) * Casper: 33-byte key with prefix (e.g., `01abc123...` for ed25519) *** ## R ### Receipts Root The root hash of the Merkle tree containing transaction receipts in a block. Used to verify events occurred. ### Relayer A node operator that monitors bridge events, signs attestations, and submits transactions. AstralBeam uses 5 relayers with 3-of-5 threshold. ### Replay Attack An attack where a valid transaction is maliciously repeated. AstralBeam prevents this using event keys and nonces. ### Robinhood Chain An Arbitrum Orbit EVM L2. AstralBeam recognizes mainnet chain ID `4663` and testnet chain ID `46630`. Their measured block times are approximately 0.1 and 0.4 seconds respectively. Both are configured for protocol `finalized` mode, mainnet remains disabled and requires separate deployment approval. The testnet V16 locker, TEST mapping, and finalized-mode round trip are verified, and the testnet route is active. ### RLP Encoding Recursive Length Prefix encoding. Used by Ethereum to serialize data structures. *** ## S ### Signature A cryptographic proof that a message was approved by a specific private key. Relayers sign attestations to authorize bridge operations. ### State Root The root hash of the blockchain's state tree. Contains all account balances and contract storage. *** ## T ### Threshold The minimum number of signatures required for a multi-sig operation. AstralBeam uses 3-of-5 (3 signatures from 5 possible relayers). ### TokenFactory The AstralBeam contract on Casper that manages token mappings, minting, and burning of bridged tokens. ### Transaction Receipt A record of transaction execution on EVM chains. Contains logs/events emitted during execution. *** ## U ### Unlock The process of releasing previously locked tokens from the bridge contract, triggered by burning wrapped tokens on the other chain. *** ## W ### Wallet Software for managing blockchain accounts and signing transactions: * MetaMask: Popular EVM wallet * Casper Wallet: Official Casper browser extension * Ledger: Hardware wallet supporting both chains ### Wei The smallest unit of ETH. 1 ETH = 10^18 wei. ### Wrapped Token A token representing an asset from another chain. Created by minting on the destination chain when the original is locked on the source chain. *** ## Related Resources * [Supported Networks](/using-astralbeam/supported-networks.md) * [FAQ](/using-astralbeam/faq.md) * [Architecture Overview](/for-developers/architecture.md) --- # Agent Instructions This documentation is published with GitBook. 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