Transaction privacy is the property of a payment or ledger system that conceals sensitive details of a transaction, such as sender, receiver and amount, from third parties while preserving verifiability of correctness. On public blockchains it is achieved through cryptographic techniques that prove a transaction is valid without revealing its contents. It addresses the inherent transparency of open ledgers, trading off auditability and regulatory visibility against confidentiality.
Overview
- Public blockchains are transparent by default, exposing addresses, amounts and transaction graphs to anyone.
- Transaction privacy hides some or all of these elements while letting the network still verify that no value was created or double spent.
- Approaches include confidential amounts via commitments, shielded pools using zero-knowledge proofs, ring signatures and stealth addresses that obscure linkage.
- These techniques restore the confidentiality users expect from cash while creating tension with anti-money-laundering and auditability requirements.
Key aspects
- Concealment of sender, recipient and amount.
- Preservation of public verifiability and consensus soundness.
- Unlinkability of transactions and addresses.
- Selective disclosure for compliance where required.
- Trade-offs between privacy, performance and regulatory acceptance.
Mechanisms
- Confidential transactions hiding amounts behind cryptographic commitments.
- Zero-knowledge proofs validating shielded transfers without revealing data.
- Stealth addresses generating one-time recipient addresses.
- Ring signatures and mixing to obscure transaction origin.
- Viewing keys enabling selective auditability.
Applications
- Privacy-focused cryptocurrencies and shielded payments.
- Confidential enterprise and supply-chain settlement.
- Private decentralised-finance transactions.
- Protection of commercially sensitive on-chain activity.
- Compliant confidentiality with auditor viewing keys.