The Evolution of Privacy
From the first shielded transaction to trustless zero-knowledge proofs. Trace Zcash's journey through 11 network upgrades and beyond.
Zcash launched as the first cryptocurrency with zk-SNARK based shielded transactions. The Sprout circuit introduced private transfers using JoinSplit proofs, establishing the foundation for financial privacy on a public blockchain.
Key Features
- First zk-SNARK cryptocurrency
- Sprout shielded pool (JoinSplit)
- Equihash proof-of-work
- Founders' Reward (20% of block rewards)
The first network upgrade established the framework for future upgrades. It introduced transaction expiry and replay protection, proving Zcash could evolve safely.
Key Features
- Transaction expiry (default 20 blocks)
- Replay protection across upgrades
- Transaction version groups
- Upgrade activation mechanism
A monumental upgrade that replaced Sprout's slow proving with Groth16 proofs, making shielded transactions 100x faster and enabling mobile wallet support for the first time.
Key Features
- Groth16 zk-SNARKs (100x faster proofs)
- New shielded pool with jubjub curve
- Sapling payment addresses & keys
- Sapling addresses and viewing keys
- Mobile-friendly shielded transactions
- Jubjub elliptic curve
- Diversified addresses for privacy
Blossom doubled block production frequency from 150 seconds to 75 seconds, increasing throughput and reducing confirmation latency while maintaining the same issuance schedule.
Key Features
- Block time reduced to 75 seconds
- 2x transaction throughput
- Adjusted block reward to maintain issuance
- Improved confirmation speed
Heartwood enabled shielded coinbase outputs, allowing miners to receive block rewards directly into shielded addresses. It also introduced FlyClient commitments to improve light client verification.
Key Features
- Shielded coinbase (miners paid privately)
- FlyClient block header commitments
- Improved light client verification
- Expanded protocol privacy coverage
Canopy replaced the original Founders' Reward with a new Dev Fund, allocating 20% of block rewards to ECC, Zcash Foundation, and community grants. Deprecated Sprout shielding to encourage migration.
Key Features
- First block reward halving
- Dev Fund: 20% of block rewards
- Dev Fund allocation - 7% ECC, 5% ZF, 8% Major Grants
- Deprecated Sprout value pool
NU5 introduced the Orchard shielded pool and the Halo 2 proving system, eliminating trusted setup ceremonies. It also introduced Unified Addresses to simplify user interactions across transparent and shielded pools.
Key Features
- Halo 2: no trusted setup required
- Orchard shielded pool (Pallas/Vesta curves)
- Unified Addresses (one address, all pools)
- Transaction Authorization using RedPallas
- Non-malleable transaction IDs
NU6 introduced the lockbox treasury system to manage post-Dev-Fund funding and aligned Zcash governance for long-term sustainability following the second halving.
Key Features
- Lockbox treasury funding model
- Revised development funding streams
- Second Zcash halving
- Updated funding governance rules
NU6.1 refined the treasury governance introduced in NU6 by enabling community and coinholder participation in funding decisions and implementing a one-time lockbox disbursement mechanism.
Key Features
- Community and coinholder funding model
- Deferred lockbox disbursement mechanism
- Extension of development funding rules
- Improved Orchard RPC reporting
NU6.2 was an emergency security upgrade that re-enabled the Orchard shielded pool with a corrected zero-knowledge proof circuit after a soundness vulnerability was identified and Orchard activity was temporarily suspended.
Key Features
- Emergency hard fork for Orchard shielded pool safety
- Corrected Orchard zero-knowledge proof circuit
- Re-enabled Orchard transactions after the temporary suspension
- Closed a soundness flaw that could have allowed counterfeit ZEC
NU6.3, named Ironwood, introduces a new Ironwood shielded pool and a public turnstile that audits value moving out of the corrected Orchard pool. It contains the earlier Orchard soundness bug and lets the community verify that the total supply of ZEC is honest.
Key Features
- New Ironwood shielded pool
- Public turnstile auditing the Orchard-to-Ironwood migration
- Orchard pool becomes spend-only
- Quantum-recoverable note format (ZIP 2005)
- Testnet — Activated October 4, 2026 · Height 4,465,026
- Mainnet — Tentative target November 5, 2026 · Height pending
The current NU7 proposal reduces target block spacing to 25 seconds, adds shielded action limits and the Network Sustainability Mechanism, removes 60% of transaction fees from circulation, and disables v4 transactions.
Sprout holders: NU7 disables v4 transactions, which current Sprout transfers require. Review migration options before Mainnet activation.
Community-maintained guidance for supported wallets and recovery material; recovery is not guaranteed.
Key Features
- Shielded action limits and 25-second target block spacing (ZIP 218)
- Network Sustainability Mechanism (ZIP 237)
- Removal of 60% of transaction fees from circulation (ZIP 235)
- Disables v4 transactions; v5 and v6 remain valid (ZIP 2003)
- Funding-stream recipient operational address update (ZIP 2008)
Target block spacing
75 seconds → 25 seconds
Scheduled issuance over time is preserved by lowering each block subsidy and lengthening the halving interval.
Official sources
- ZIP 259: Deployment of the NU7 Network Upgrade (Draft)
- ZIP 200: Network Upgrade Mechanism
- ZIP 201: Network Peer Management mechanisms apply
- ZIP 207: Funding Streams (revision 2)
- ZIP 214: Consensus Rules for a Zcash Dev Fund (revision 3)
- ZIP 218: Consensus rules for block spacing and shielded action limits
- ZIP 235: Remove 60% of Transaction Fees From Circulation
- ZIP 237: Network Sustainability Mechanism
- ZIP 2003: Deprecate v4 transactions
- ZIP 2008: Update to FS_FPF_ZCG_H3 address list
- Zcash Foundation NU7 rollout update