Zcash¶

Zcash (ZEC) is the first cryptocurrency to widely apply zk-SNARKs (Zero-Knowledge Succinct Non-Interactive Arguments of Knowledge) technology, launched in 2016. Built on Bitcoin's codebase, it adds an encryption layer that allows users to freely choose between fully transparent public transactions and fully confidential shielded transactions.

Problems It Solves¶

Zcash was born from the need to improve Bitcoin's privacy protection capabilities. In commercial applications and personal financial management, a completely public ledger (like Bitcoin), while transparent, also exposes too much sensitive information. Zcash seeks to find a balance between regulatory compliance (disclosable when auditing is needed) and maximum privacy (fully confidential when disclosure is not needed).

Implementation Mechanism and Principles¶

Zcash's core is the zk-SNARKs protocol, which allows network nodes to verify transaction validity (funds have not been double-spent, inputs equal outputs) without knowing the transaction amount, sender, or receiver.

Two Address Types¶

Zcash provides a unique dual-address system: 1. t-addr (Transparent Address): Starts with t, functions identically to Bitcoin addresses with publicly visible transaction details. 2. z-addr (Shielded Address): Starts with z, supports privacy transactions.

Four Transaction Types¶

Based on these two address types, Zcash supports four transaction modes: * Public (t-to-t): Similar to Bitcoin, no privacy. * Shielding (t-to-z): Funds move from a transparent address into the shielded pool, breaking the funding trail. * Deshielding (z-to-t): Funds move from the shielded pool out to a transparent address. * Fully Shielded (z-to-z): Sender, receiver, and amount are all encrypted on the blockchain; only those with the Viewing Key can see them.

Protocol Upgrade History¶

Zcash's zero-knowledge proof technology has undergone several major iterations: * Sprout (2016): The initial version; proof generation was extremely slow, requiring large amounts of memory, and needed a Trusted Setup. * Sapling (2018): A revolutionary upgrade that reduced proof generation time from minutes to seconds, dramatically lowering memory requirements and making shielded transactions on mobile device wallets possible. * Orchard (2022): Introduced as part of the NU5 upgrade, it brought the Halo 2 proof system, eliminating dependence on a trusted setup (Trustless), further enhancing security and scalability.

Optional Disclosure¶

A key feature of Zcash is Viewing Keys and Payment Disclosure. Users can proactively share specific transaction details with third parties (such as auditors or tax authorities) to prove compliance, without exposing their entire wallet history.

Key Features¶

Scientific Rigor: Zcash is developed by a team of top cryptographers (including one of the inventors of ZKP), dedicated to translating the latest academic results into engineering practice.
Selective Privacy: Users have control over their own data, choosing when to protect privacy and when to be transparent.
Encrypted Memo Field: Shielded transactions include an encrypted memo field, allowing senders to securely attach messages (such as invoice numbers, private letters) during transfers, complying with banking standards (ISO 20022).