Is it possible that there is counterfeit zcash in one of the private pools?
I feel like zcash’s long-tail transparency on issues like this is important.
You are referring the bug that could have happened in the Sprout pool:
We believe that no one else was aware of the vulnerability and that no counterfeiting occurred in Zcash for the following reasons:
• Discovery of the vulnerability would have required a high level of technical and cryptographic sophistication that very few people possess.
• The vulnerability had existed for years but was undiscovered by numerous expert cryptographers, scientists, third-party auditors, and third-party engineering teams who initiated new projects based upon the Zcash code.
• The Zcash Company has seen no evidence that counterfeiting has occurred as might be discovered by monitoring the the total amount of Zcash held in Sprout addresses (i.e., the Sprout shielded pool). As long as the value in the shielded pools are greater than zero, no counterfeiting has been detected. Bitfly’s Zcha.in displays these values on the network statistics page, and Zcash nodes report them in the output of the getblockchaininfo command.
• Upon discovering the vulnerability, the Zcash Company took extraordinary measures to minimize the possibility of exploitation. The specifics of our steps taken are documented in the detail below.
• The Zcash Company studied the blockchain for evidence of exploitation: An attack might leave a specific kind of footprint. We found no such footprint.
Further:
Defense Against Counterfeiting in Shielded Pools - Electric Coin Company
The developers have implemented a protocol that will not allow bogus coins (more than the total are currently existing in the Sprout pool to exit the Sprout pool) to prevent breaking the 21M coin cap. There is currently only around 25k ZEC remaining in that pool.
Theoretically if an attacker had known about this bug, and it was not already patched, then they could theoretically counterfeit (fake proofs) for the 25k ZEC in Sprout and remove it from the pool themselves. But even in that scenario, that would only affect the few person’s who still have ZEC in that pool and it would not add to the total coins in circulation nor affect the security of any other pools.
This is one of the reasons we encourage users to get their funds out of Sprout into a better more modern pool, so Sprout can be fully depreciated.
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