Glossary

Terms used across Starknet Privacy documentation

Term	Meaning
Privacy pool	Smart contract holding pooled ERC-20s and enforcing proofs + write-once state.
Note	Immutable record of ownership of an amount of a token; spent via nullifier.
Nullifier	One-time value revealed when spending a note; prevents double-spend; unlinkable without viewing key.
Channel	Unidirectional link sender → recipient; first send opens it and shares channel key (encrypted to recipient).
Channel key	Shared secret derived from sender/recipient viewing material; indexes note locations.
Subchannel	Per-channel, per-token lane for notes (avoids extra channel opens per asset).
Viewing key	Key pair: private (k) for decrypt/trace/nullifier; public (K) for encrypt-to-user.
Client-side action	High-level user intent (open channel, use note, withdraw, …).
Server-side action	Primitive the contract runs (WriteOnce, append channel, ERC-20 transfer).
WriteOnce	Storage write only if cell is zero—immutability.
Open note	Note whose encoding uses a reserved salt so the filled amount is plaintext on-chain; used when an external contract must set the amount after the proof (e.g. AMM output).
Invoke	Final transaction phase: one call from the pool to an external contract (InvokeExternal or ComputeAndInvoke) that can fill open notes.
Compute-and-invoke	Invoke variant where the pool first passes the user’s identity key to the target’s privacy_compute, then calls privacy_invoke_with_computation with the result.
Identity key	Per-user, per-target value derived inside the proof from the user’s address and private viewing key; never published on-chain.
Shadow account	Per-user, per-dApp account contract, driven only by the shadow account anonymizer, that runs dApp calls without revealing the user.
Paymaster	Relayer that submits txs and is reimbursed from the pool.
Auditing entity	Holder of k_audit; decrypts escrowed viewing keys under compliance process.
Stwo	STARK prover used for client-side Cairo proofs.