First of all, you should be familiar with C language, and then go to the library to borrow an encryption and decryption book, which contains the implementation code of des (there is such a book, I have seen it). This paper first introduces the history and development status of encryption and decryption, and then focuses on the development history and principle of des encryption (the above contents should be expressed in their own language by borrowing more relevant books). Then write a des algorithm program (you can use the program in the book), and then cut some pictures of the running results. Finally, to sum up, the paper will do.