Zcash

The Zerocash paper published on 18 May 2014 proposed decentralized anonymous payments using succinct zero-knowledge proofs. Electric Coin Company formed in 2015 to turn that research into Zcash, which launched in October 2016 with transparent addresses and a shielded Sprout pool.

Privacy was optional rather than universal. Transparent transactions expose values and addresses, while shielded transactions hide payment details inside cryptographic commitments and proofs. Wallet records, exchanges, network metadata, address reuse, and movement between pools can still reveal information outside the proof system.

Network Upgrade 5 activated on 31 May 2022 at block 1,687,104. It introduced the Orchard shielded protocol, Halo proofs without an Orchard trusted setup, and Unified Addresses that let wallets package compatible receiver types behind one address.

The live ecosystem now centers shielded-capable products such as Zodl (formerly Zashi) while preserving transparent compatibility. Protocol capability does not guarantee shielded use: sender, recipient, wallet, exchange, and service support determine whether a payment stays private end to end.

ZEC has a 21-million maximum supply and is issued through proof-of-work block rewards. At NU6.1 height 3,146,400, 78,750 ZEC accumulated under the earlier lockbox was paid once to a 2-of-3 multisig whose key holders are Zcash Foundation, ECC and Shielded Labs. The rules also continue 8% of subsidy for ZCG and 12% for the deferred lockbox through height 4,406,400. Those signers and grant processes control allocated funds; ordinary ZEC holders do not own a proportional share.

ZEC pays fees and can be mined, held, and transferred through transparent or shielded pools. The reviewed protocol materials do not establish that holding ZEC alone grants equity in Electric Coin Company or the Zcash Foundation, a fixed-value redemption claim, a contractual share of development-fund revenue, or a general governance vote; separate contracts and legal rights are outside that evidence.

On 29 May 2026, an AI-assisted audit reported an Orchard circuit flaw that could have permitted invalid balance creation and theft if exploited. The emergency response disabled Orchard while developers prepared a corrected circuit; the record does not establish that an attacker used the flaw.

NU6.2 activated at block 3,364,600 on 3 June 2026 and re-enabled Orchard with the fix. The incident is material even without proven exploitation because zero-knowledge soundness is a monetary-security boundary, and emergency upgrades create coordination and availability costs.

On 28 July 2026, NU6.3 activated Ironwood at block 3,428,143. It prohibited new value from entering Orchard and required funds leaving that pool to pass through a publicly visible turnstile before entering Ironwood. That boundary lets observers compare the old pool’s inflows and outflows, while moving new shielded activity to the replacement pool.

ZIP 2005 still carries a Proposed header, yet NU6.3 activated its recoverable note format for Ironwood. The distinction matters: those notes are structured for a possible future Recovery Protocol, but that protocol is not deployed and the change does not make present Zcash quantum-safe. Sprout, Sapling and pre-Ironwood Orchard funds do not acquire recoverability.