[ Essentially, my answer is a follow-on to the answer by @Ixrec above. ]
An important question: is the number of distinct combinations that you need to cover is going to grow? You are better aware of your subject domain. This is your judgement to make.
Can the number of variants possibly grow? Well, that's not inconceivable. For example, you may need to accommodate more different encryption algorithms.
If you anticipate that the number of distinct combinations is going to grow, then Strategy pattern can help you. It's designed to encapsulate algorithms and provide an interchangeable interface to the calling code. You would still have a small amount of logic when you create (instantiate) the appropriate strategy for each particular string.
You have commented above that you don't expect the requirements to change. If you don't expect that the number of variants would grow (or if you can defer this refactoring), then keep the logic the way it is. Currently, you have a small and manageable amount of logic. (Maybe put a note to self in the comments about a possible refactoring to a Strategy pattern.)
