The issue with renaming CryptoKitError is that on Apple platforms these errors actually come from CryptoKit. Changing the error there is pretty hard: it would represent an ABI break to rename completely, even with the typealias, so that’s not tenable, meaning there’d be two similar errors only one of which is thrown.

While I agree this is a paper cut, I don’t think this issue is severe enough to warrant a change. But I’d be happy to hear disagreement.

Adding a typealias for CryptoKitError to CryptoError wouldn't break anything right? All the original stuff would continue to work but people using Swift Crypto would be able to catch and deal with CryptoErrors instead of knowing about CryptoKit

Yes, the typealias in the reverse direction will work.