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.

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 supports the testnet (chain ID 46630), where the bridge route is active. Mainnet (chain ID 4663) support is planned.

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.