Write a program in C to decrypt a cipher text using Caesar Cipher substitution method.Plain text was first encrypted with a Cipher Key within the range 1 to 26 and then encrypted then encrypted with...

Write a program in C to decrypt a cipher text using Caesar Cipher substitution method.Plain text was first encrypted with a Cipher Key within the range 1 to 26 and then encrypted then encrypted with key -1 (minus 1).Find the first key and write the key numbers and the decrypted plain text into text mode file "done.txt" using your program