Apple Developer Swift

Apple Introduces Swift Crypto

There are many things that can mark the maturity of a programming language. Things like Application Binary Interface, or ABI, stability, Application Programmer Interface, or API, consistency, the re-working of the language syntax, or the inclusion of a vital feature within the language. It has been five and half years since Apple introduced its own programing language, Swift.

In the years since its introduction Swift has undergone a huge transformation since its initial release. With Swift 3, the entire syntax of the language was redone so that it had a consistent naming and its syntax was significantly shortened. Swift 5 introduced a new Swift-only interface language called SwiftUI. and with Swift 5.1, ABI stability came into existence. One thing that has been missing from Swift has been its own native Cryptographic library. That has now changed.

Swift Crypto

At the dot Swift conference Apple introduced a new feature to the Swift programming language, Swift Crypto. Swift Crypto is an open-source re-implementation of Apple’s objective-c framework CryptoKit. There are a few things that make Swift Crypto a bit different from other cryptographic frameworks.

The first is that Swift Crypto is not built into the Swift language itself. Instead, it is implemented as a Swift Package. This has a couple of added benefits. The first benefit is because it is a Swift Package, it can be independently updated outside of the core Swift language. This means that should a vulnerability be found in the package or its implementation it can be fixed and a new release be made. Similarly, if new algorithms become standard, these too can be implemented without requiring a new version of Swift. Furthermore, this means that if you need to keep on an older version of a language you do not need to sacrifice security.

The second benefit is that this package will work on all of Apple’s platforms, macOS, iOS, tvOS, and watchOS, as well a on Linux. The fact that the package will work on Linux means that both your server side code and client code can use the same cryptographic libraries.


Swift Crypto uses Google’s BoringSSL framework for implementing the cryptographic primitives and therefore does not re-implement these, but only on non-Apple Platforms. If you use Swift Crypto on Apple’s platforms, it defers to CryptoKit. That does not mean that you should not use Swift Crypto within your project though. While it will defer to CryptoKit, using Swift Crypto will provide you a consistent interface across all platforms, which will make your code easier to maintain.

Secure Enclave

Apple’s native CryptoKit APIs implements some interfaces to Apple’s security hardware processor, called Secure Enclave. Because Swift Crypto will work on both Apple’s platforms as well as Linux, results in Swift Crypto not implementing these APIs. Hence, if you need to utilize the Secure Enclave APIs, you will still need to use the CryptoKit APIs to implement these.

Closing Thoughts

The addition of a Swift-native Cryptographic library will make it easier in a couple of ways. First, by allowing the same Swift Package to be used across Apple’s platforms as well as Linux. While Swift Crypto will not implement the Secure Enclave APIs, any implementations made within CryptoKit will also be done within Swift Crypto.

Being a Swift Package, Swift Crypto can be kept up to date with the changing landscape of cryptography independent of relying on a new version of Swift to have any changes implemented.

The addition of Swift Crypto should allow a consistent implementation between server-side code as well as client code making it easier to implement the features, regardless of platform. Swift Crypto does require Swift 5.1 or later and the package is semantically versioned and, as of this writing, is at version 1.0.0. If I need to implement any cryptographic items within my projects, I will likely use Swift Crypto