How Zcash Enables Privacy Through Shielded Transactions

1. Shielded Addresses vs Transparent Addresses

• Transparent addresses operate like those on Bitcoin: transaction details and balances are visible to anyone on the blockchain.
• Shielded addresses keep transaction details (sender, recipient, and amount) private by using zk-SNARKs, encrypting this information on the blockchain123.

2. zk-SNARKs: The Privacy Engine

• zk-SNARKs allow someone (the prover) to prove something is true to another party (the verifier) without revealing the underlying information.
• In Zcash, this means a user can prove they own the amount they wish to send and that the transaction follows all consensus rules, without revealing addresses or amounts involved2435.

3. Shielded Transactions in Practice

• When sending from a shielded address, the transaction data is encrypted.
• A zk-SNARK proof is generated, enabling the network to validate the transaction’s legitimacy while keeping details hidden.
• Shielded transactions thus ensure confidentiality of financial information, balancing privacy and network integrity6473.

4. Selective Disclosure and Compliance

• Zcash enables selective disclosure: users with shielded addresses can share transaction details with trusted third parties via a "viewing key." This supports compliance and regulatory needs without sacrificing typical privacy6.

5. Trade-offs and Advances

• The computation required for zk-SNARKs is heavier than for transparent transactions, affecting resource use and occasionally processing speed.
• Upgrades such as Sapling, Orchard, and the Halo proving system (removing the trusted setup) have improved privacy, efficiency, and scalability over time43.

Summary Table