Such addresses give away no information on today’s computers. Each Zcash address carries a public key built from the wallet’s viewing key, the secret a wallet uses to spot payments sent to it, using one-way elliptic-curve math similar to what protects bitcoin and ether wallets.
Ordinary computers can’t run that math in reverse, but a large enough quantum computer running Shor’s algorithm, a method published in 1994 for exactly that job, could theoretically work backward from the address to the key.
That’s the real threat hanging over Satoshi-era bitcoin, whose public keys already sit onchain for anyone to copy. Last week, Google said its Willow quantum chip had produced near-perfect versions of one of the components such an attack would burn through, a step toward a machine powerful enough to try it.
Quantum computers capable of that are still likely years away (and no one has a firm timeline for when one could be built), but it’s a problem developers across the industry are rushing to solve.
One key for every swap
Zcash’s architecture creates its own problem. A Zcash wallet can generate many addresses that look unrelated, but they usually share one viewing key.
An attacker who cracks that key from a single published address could link every payment the account ever received and read the amounts and the private notes, or memos, attached to them.
