Blockchains are usually praised for being transparent. Every transaction is recorded on a public ledger that anyone can look at, forever. This is genuinely one of the technology's great achievements: it lets complete strangers agree on what happened without needing to trust each other or a middleman. Cardano, like most public chains, is built on exactly this principle, and it works beautifully for a huge range of uses.

But transparency has a shadow side that we don't talk about often enough. The same openness that makes a blockchain trustworthy can make it unusable for anything you'd reasonably want to keep private. In the previous articles we introduced Midnight as Cardano's privacy-focused partner chain and hinted that it exists to fill…