Glossary
Reference definitions for terms used throughout Orbinum documentation.
A
Account
A unique identifier on the blockchain that can hold balances and submit transactions. Orbinum supports both Substrate accounts (Sr25519) and Ethereum accounts (secp256k1).
Arkworks
A Rust ecosystem for zkSNARK programming. Orbinum uses arkworks for native proof generation.
B
Base Fee
The minimum gas price for EVM transactions, dynamically adjusted per EIP-1559 based on network utilization.
Blinding Factor
A random value added to commitments to ensure unlinkability. Without knowing the blinding factor, observers cannot determine what value a commitment represents.
BN254
An elliptic curve (also known as alt_bn128) used for pairing-based cryptography. Provides the mathematical foundation for Groth16 proofs.
C
Circom
A domain-specific language for defining arithmetic circuits used in zero-knowledge proofs.
Commitment
A cryptographic hash that hides a value while allowing later verification. In Orbinum: commitment = Poseidon(value, pk, blinding).
Constraint
A mathematical equation that must be satisfied in a zero-knowledge circuit. More constraints increase proving time but enable more complex logic.
E
Extrinsic
A Substrate transaction or inherent data. Extrinsics are the way users interact with the blockchain.
EVM (Ethereum Virtual Machine)
A stack-based virtual machine that executes smart contract bytecode. Orbinum provides full EVM compatibility via Frontier.
F
Frontier
A set of Substrate pallets that implement Ethereum compatibility, including EVM execution and Ethereum RPC.
Full Node
A node that stores and validates all blockchain data. Can serve RPC requests but does not produce blocks.
G
Groth16
A zkSNARK proving system known for constant-size proofs (192 bytes) and fast verification. Requires a trusted setup per circuit.
H
Historic Root
A previous Merkle root stored to allow proofs built against older states to remain valid.
M
Merkle Tree
A tree data structure where each leaf is a hash and each non-leaf is a hash of its children. Enables efficient membership proofs.
Merkle Proof
A path from a leaf to the root that proves the leaf exists in the tree without revealing other leaves.
N
Note
A private UTXO in the shielded pool, containing a value, owner, and blinding factor.
Nullifier
A unique identifier revealed when spending a note. Prevents double-spending while preserving privacy. nullifier = Poseidon(commitment, sk).
P
Pallet
A Substrate module that implements specific blockchain functionality. Pallets are composable building blocks.
Poseidon
A hash function optimized for zero-knowledge circuits. Uses ~300 constraints compared to ~25,000 for SHA256.
Powers of Tau
A multi-party computation ceremony that generates random parameters for zkSNARK trusted setups.
Precompile
A built-in function at a specific address in the EVM that executes native code instead of bytecode.
Private Transfer
A transaction that moves value between shielded notes without revealing sender, recipient, or amount.
Proof
Cryptographic data that verifies a statement is true without revealing why it's true.
Proving Key
The key used to generate proofs for a specific circuit. Created during trusted setup.
R
R1CS (Rank-1 Constraint System)
A constraint format used to represent arithmetic circuits. Circom compiles to R1CS.
RPC (Remote Procedure Call)
An interface for external applications to interact with the blockchain.
Runtime
The state transition function of a Substrate blockchain. Contains all pallets and business logic.
S
Shield
Convert public balance to shielded balance by creating a note commitment.
Shielded Pool
The smart contract/pallet that manages private notes using a Merkle tree of commitments.
SnarkJS
A JavaScript library for zkSNARK proof generation and verification.
Spending Key
A private key that authorizes spending notes. Used to compute nullifiers.
Substrate
A modular blockchain framework developed by Parity Technologies.
T
Trusted Setup
A ceremony that generates proving and verification keys for Groth16. Security requires at least one honest participant.
U
Unshield
Convert shielded balance back to public balance by revealing a nullifier and proving ownership.
UTXO (Unspent Transaction Output)
A model where balances are represented as discrete outputs that can be spent once. Used by Bitcoin and Orbinum's shielded pool.
V
Validator
A node that participates in consensus and produces blocks.
Verification Key
The public key used to verify proofs. Published on-chain.
W
Witness
Private inputs to a circuit that satisfy all constraints. The witness is never revealed.
Weight
Substrate's measure of computational resources. Similar to gas but more granular.
Z
Zero-Knowledge Proof (ZKP)
A cryptographic proof that demonstrates knowledge of information without revealing the information itself.
zkSNARK
Zero-Knowledge Succinct Non-Interactive Argument of Knowledge. A type of ZKP with small proofs and fast verification.