[Cryptography] Swift and cryptography

[Arnold Reinhold]

Apple's new programming language, Swift, seems to be a clean, modern and well thought out design, with a number of improvements that remove possible sources of programming errors.  In particular, Swift faces the integer overflow problem head on, perhaps the first modern language to do so (see http://blog.regehr.org/archives/1154). Integer overflows in Swift cause a runtime error, but programmers can choose to allow overflows by using the special arithmetical operators &+, &-, &*, &/ and &%. Swift also allows types to have properties, and the properties 'min' and 'max' are defined in Swift for all integer types, e.g. UInt8.max, which is 255.  They can be used to safely check for potential overflows, as contrasted with relying on--and remembering--the names of min/max constants defined in some external library.

Swift is still in beta and there still might be time for the cryptography community to influence its design. Yes, I realize Swift is an Apple-only language at the moment, but this could change and getting things right on one platform is at least a start.  

One area that comes to mind is some way to erase data that is guaranteed not be removed by the optimizer. Swift has destructors ("deinitializers") for classes. A guarantee that assignments in deinits would always be preserved might be a start. Swift also has "optional" variables that can either have a value or be nil. A zeroize generic function or protocol that erased all storage associated with an optional variable before setting it to nil could also be helpful. 

Another possibly helpful improvement would be a circular shift operator.  Swift allow operator overloading, but it would be nice if circular shift were built in. 

Other thoughts on desirable cryptography and security features for Swift?

Arnold Reinhold