"zk-SNARKs – the zero-knowledge proofs at the core of Zcash – require a parameter generation ceremony to take place for every statement that you wish to create proofs about. Although privacy is protected by zk-SNARKs unconditionally, if this ceremony is compromised it becomes possible to counterfeit Zcash. It is thus important for us to ensure these parameters are created securely."
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https://z.cash/blog/new-mpc-protocol.htmlSo I don't understand why anyone would not consider it possible for BitcoinZ to be counterfeited.