Target 600 $
"Finally — and most significantly — University of Michigan-Dearborn researcher Jeffrey Quesnelle published a paper that raised questions about the privacy of Zcash’s shielded addresses.
Quesnelle found that — at least the way most people currently use the shielded address feature — 31.5 percent of transactions using zk-SNARKS cryptography could be circumstantially linked to their original address.
Zcash’s Zooko Wilcox and Jack Gavigan wrote a blog post addressing the research, stressing that it had not uncovered any security vulnerabilities. However, they conceded that many users misunderstand how shielded addresses should be used, which is why they inadvertently sacrifice their privacy when using this feature.
“To protect yourself from this sort of exposure, don’t think of shielded addresses as something you pass money through, think of them as something you store money in. Storing money in a shielded address and sending a portion of it out as needed gives you very strong privacy. Moving money into it and then immediately moving that money out again does not,” Wilcox and Gavigan wrote.
Monero developer Riccardo Spagni expressed a hint of vindication on Twitter, recalling that NSA whistleblower Edward Snowden had praised the Zcash project but referred to Monero as “amateur crypto“.
“Turns out that 31.5% of the handful of ZCash private transactions are traceable. What’s that quote again? Oh yes – ‘Great project, but the problem with amateur crypto is mistakes happen and have huge consequences for people like me,'” Spagni wrote."