Am trying to develop an algorithm that can be able to encrypt and decrypt data and cut it into smaller chunks then returns it into their original form am trying to do it in c#

To reasonably expect help from people, you would need to ask some sort of a question or describe some sort of a problem. So what specific problem related to your project is that the you would need help with? What code have you written? What is the problem with your code? Get any errors? Where do you get your errors? What errors do you get?