Glossary
Glossary
Anonymity Set
A quantitative metric representing the total number of transactions or entities within which a specific user is indistinguishable. A larger anonymity set increases the "probabilistic noise," making it mathematically infeasible for chain analysis tools to isolate a single participant's activity.
Commitment Scheme
A cryptographic "envelope" that allows a user to commit to a specific value (e.g., a token amount) while keeping it hidden from others, with the ability to reveal or prove properties of that value later. Most shielded ledgers use a Merkle Tree of Commitments to manage the state of private assets.
Nullifiers
A unique, deterministic identifier revealed when a private "commitment" (asset) is spent. Nullifiers prevent the double-spending problem in zero-knowledge environments; they allow the protocol to track that a specific note has been consumed without revealing which note it was or the identity of the spender.
On-Chain Surveillance & Heuristic Analysis
The systematic monitoring of distributed ledgers using pattern recognition and graph theory. Surveillance entities correlate transaction timing, address reuse, and UTXO "dust" to de-anonymize users. Shielded protocols are designed to neutralize these specific attack vectors by breaking the deterministic link between inputs and outputs.
Privacy-Preserving Smart Contracts
Smart contracts that execute logic on encrypted state variables. By utilizing ZKPs or Trusted Execution Environments (TEEs), these contracts allow for private DeFi interactions (e.g., dark pools, private lending) where the trade volume and user balance remain confidential from the public observer.
Relayer Infrastructure
An abstraction layer that decouples the transaction sender from the on-chain gas payer. Relayers submit ZK-proofs to the network on behalf of the user, preventing Metadata Leakage (such as IP addresses or gas-funding wallet links) that would otherwise compromise the user's anonymity.
Shielded Transactions
A transaction primitive that utilizes asymmetric encryption and zero-knowledge proofs to obfuscate transactional metadata. Unlike transparent (pseudonymous) transactions, shielded transactions encrypt the transaction graph (sender/receiver) and the state (value), ensuring ledger integrity is maintained without exposing sensitive data to the public consensus layer.
Viewing Keys (Selective Disclosure Keys)
A hierarchical key structure (often divided into Incoming and Outgoing viewing keys) that allows for the decryption of transaction data without granting spending authority. These are the cornerstone of Compliance-Ready Privacy, enabling users to provide read-only access to auditors or regulators for AML/KYC transparency.
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Zero-Knowledge Proofs (ZKP)
A cryptographic protocol that enables a Prover to demonstrate to a Verifier that a specific computational statement is valid (the witness) without revealing the underlying data. In "Invisible Ledger" architectures, ZKPs validate that a transaction adheres to protocol rules (e.g., non-negative values, valid signatures) without leaking plaintext information.
zk-SNARK (Succinct Non-Interactive Argument of Knowledge)
A specific ZK construction optimized for blockchain environments. Its primary characteristics are: Succinctness: Proofs are only a few hundred bytes, regardless of the complexity of the underlying computation. Sub-linear Verification: Verification time is near-instant, allowing Resource-constrained environments (like the EVM) to validate private transactions at a low gas cost.