c++ code please

write a program that can perform encryption and decryption using an arbitrary substitution cipher. In this case, the encryption array is a random shuffling of the letters in the alphabet. Your program should generate a random encryption array, it corresponding decryption array, and use these to encode and decode a message.

Note: Allow for the saving and loading of encrypted messages by storing the 26 letter encryption key amongst the n encoded characters of the message. Note that for an n character message, there will be n+1 slots amongst them. For a 1-character message, for instance, there is a slot before the character and a slot after the character. For a 2-character message, there are slots before and after the first character and after the second character. And so on... Make sure the extra 26%(n+1) letters from the encryption key are located carefully to make the spread nice and even. (Note that when the message is longer than 25 characters, each letter of the key is alone by itself and, in fact, you are spreading the characters of the message amongst the 27 slots around the key values now.)