Structured data has a 'histogram' that is vastly different than CBC encrypted data. CBC encrypted data has a 'flat' histogram, where as structured data has a different signature.
Create a program that creates data histograms and you'll see what I mean. There are much easier ways to tell as well, like FOURCC or magic bits for files, for instance a gif file always starts with GIF89, or JPEGs start with JFIF, same with zip files, tar, etc. Almost every file can be recognized independently of it's name, by it's structure.
If you reverse engineer stuff sometimes you'll be given files that you don't even know the structure of and have to figure out what are offsets and what is data. Samething with reverse engineering compiled code.
Create a program that creates data histograms and you'll see what I mean. There are much easier ways to tell as well, like FOURCC or magic bits for files, for instance a gif file always starts with GIF89, or JPEGs start with JFIF, same with zip files, tar, etc. Almost every file can be recognized independently of it's name, by it's structure.
If you reverse engineer stuff sometimes you'll be given files that you don't even know the structure of and have to figure out what are offsets and what is data. Samething with reverse engineering compiled code.