Qtum (@qtum): 6 years ago we published a whitepaper about privacy on Qtum.

6 years ago we published a whitepaper about privacy on Qtum. You can still read it here: https://eprint.iacr.org/2020/156.pdf "We propose an efficient privacy protocol using zk-SNARKs based on smart contracts. It helps to make several decentralized applications, like digital assets, stable coins, and payments, confidential." At that time, we were warned by multiple exchanges that we'd be delisted if we went through with this, so development was halted. It seems like that narrative has shifted since 2020. While the paper is a bit dated, the fact remains that Qtum is well positioned to implement Phantom tech to our UTXO+EVM layer1 stack. We've decided to begin work on an updated version of this whitepaper. With $USDC coming to Qtum in the next few weeks, it makes sense to revisit privacy. We believe it's important to have this as a foundational layer on which we can attempt to build out a better ecosystem on Qtum. To prepare for this, we've signed on with a security partner to get Qtum Core audited in October. Once that is complete, we'll begin work on a privacy solution. We'll keep everyone updated on our progress.