Cryptography makes up a large part of our technological lives, and in some cases, we never realize that
cryptography is working. Do you have a PIN number on your iPhone? The drive is encrypted! Do
you use Bitlocker or Cryptdata on your Operating System? Your drive is encrypted! Do you visit most
websites? Well most use HTTP Secure via SSL/TLS! Do you use an email service like ProtonMail?
Your emails are encrypted… and in all of these cases, you never really interact with the cryptography.
Instead, it just happens in the background.
What will we do?
Below are a few cryptographic tasks to make sure you’re familiar with various methods of
cryptography – from simple ciphers to RSA!
1) Caesar’s Cipher
2) Create your own Cryptography using a Substitution Cipher. Include your SHORT plaintext, the
substitution key, along with the cipher text! Please provide Excel or source code if you decide to
implement this in a programming language or Excel.
3) Encrypt this number (base 10) using the Public key. (All numbers in base 10 to make it easier).
M = 108
n = 7387
e = 4
4) You received this cipher text message (Base 10) which is supposed to have been encrypted using
your public key. Decrypt the message using the following Private key. (All numbers in base 10 to
make it easier).
C = 6342
n = 7387
d = 4811
