Blockchain-program(easy)
A simple and very old method of sending secret messages is the substitution cipher. You might have used this cipher with your friends when you were a kid. Basically, each letter of the alphabet gets replaced by another letter of the alphabet. For example, every 'a' get replaced with an 'X', and every 'b' gets replaced with a 'Z', etc. Write a program thats ask a user to enter a secret message. Encrypt this message using the substitution cipher and display the encrypted message. Then decryped the encrypted message back to the original message. You may use the 2 strings below for your subsitition. For example, to encrypt you can replace the character at position n in alphabet with the character at position n in key. To decrypt you can replace the character at position n in key with the character at position n in alphabet. Have fun! And make the cipher stronger if you wish! Currently the cipher only substitutes letters - you could easily...