The tag coding-theory now exists.
After some discussion in the chat, I propose to create a new tag about Information- and Coding theory. We've already had a number of challenges that would fit this tag very well and I think there are many more to come. It would add context to those challenges that is not possible to express with the current tags. So far the only tags that go in this direction are compression, error-correction and kolmogorov-complexity, (also checksum , cryptography ), which are just three specific areas of this topic.
Originally I proposed "coding-theory", but that alone would (perhaps?) be prone to be misunderstood, so I'd suggest information-theory, as "information- and coding theory" would be too long. Furthermore both topics usually go hand in hand, even if information theory technically contains coding theory as a field.
In the following list I collected a few examples (there are many more) that I think would fit very well: