Up next: what do real-world credential systems look like?
Browser compatibility
，更多细节参见谷歌浏览器下载
We can modify our ZK credential to support a limit of N shows as follows. First, let’s have the User select a random key K for a pseudorandom function (PRF), which takes a key and an arbitrary input and outputs a random-looking outputs. We’ll embed this key K into the signed credential. (It’s important that the Issuer does not learn K, so this often requires that the credential be signed using a blind, or partially-blind, signing protocol.3) We’ll now use this key and PRF to generate unique serial numbers, each time we “show” the credential.
Also, for the first time, the MacBook Air will support up to 4TB of local storage.