Zcash Digital Coin is an open and programmable financial system, privacy is the only way to ensure fungibility and guarantee that cryptocurrency can be interchangeable as a fluid medium of exchange for users. Companies need the protection of privacy along their supply chain in order to conduct their business, especially in the context of public blockchains. In addition, we believe that personal privacy is necessary for core human values like dignity, intimacy, and morality.
The Zcash total coin supply is going to be 21 million like Bitcoin, and it even follows the same issuance rate with 21m ZEC being issued over 131 years, but instead of having 10 minute blocks, ZCash will have a 2.5 minute block avarage with 4 times bigger block rewards that halve every 4 years.
Zcash: a decentralized mix. Miers et al. [MGGR13] proposed Zcash, which extends Bitcoin to provide strong anonymity guarantees. Like many e-cash protocols (e.g., [CHL05]), Zcash employs zero-knowledge proofs to prevent transaction graph analyses. Unlike earlier practical e-cash protocols, however, Zcash does not rely on digital signatures to validate coins, nor does it require a central bank to prevent double spending. Instead, Zcash authenticates coins by proving, in zero-knowledge, that they belong to a public list of valid coins (which can be maintained on the block chain). Yet rather than a full-fledged anonymous currency, Zcash is a decentralized mix, where users may periodically “wash” their bitcoins via the Zcash protocol. Routine day-to-day transactions must be conducted via Bitcoin, due to reasons that we now review.
The first reason is performance. Redeeming Zcash coins requires double-discrete-logarithm proofs of knowledge, which have size that exceeds 45kB and require 450ms to verify (at the 128-bit security level).3 These proofs must be broadcast through the network, verified by every node, and permanently stored in the ledger. The entailed costs are higher, by orders of magnitude, than those in Bitcoin and can seriously tax a Bitcoin network operating at normal scale.
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