Assignment #2 – CryptographyCryptography 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
5) Use the following online tool to decrypt an AES 128 ciphertext (base64) using the ECB encryption
cipher with a 128 bit key, also given below (Base64 ciphertext). https://www.devglan.com/onlinetools/aes-encryption-decryption
KEY: CSITCYBR555HOOD!
(Base64 Cipher Text using ECB cipher scheme):
WV8j7RV0XX+8nawUcVrJ3O2H2kCVz7CHSvcD0Dh3y6vOWzwKegu5WpkFCPhdxFH00Qvut2m5
h5qxpStKOrK/
BZlhUncwUGBg5yhm1+d9tKpAiuv1oli0imtErd0pbCYn0pWMqrVobauHE+jCOt9diqtriR6bCsj29pTq
IRTrJqp3REJJ2XrpjWILe4R/URiIGMFIvXdkcZuqeBg5Q6ZWV9QKNPeejlaufXFNb/k1qa1b/+IJ/
u9myavisRCZcpfc/
VtTByUO0sOvy8Yj4hZmlbi9hJvio4YHMwScvgeml1N7m3FKmutaZNsi4b6b2+1DhbfWD+Vs8tLPs
UTc6I3XclEAOMMHOFbrJVkQKdcIivUaYAm2qdv+AdJJS4jWz9xdFF5Tikv2NyclXIFlfphyuk502m
InMiN2QXBMdbnGdoCWq4+OyfGan7RiLJiYMWLqRT9OXQ5+VvG4YPAQZFbNO+WtK6aWml2
nr3wwY3tFgNNyonHNRu5Eyz2sllItyhX+RHl6RcgKMUoLA6Tl8nUGB0EDY7TdeKOobqBS4yO+2
HTS90EdbjRcCfrWM7oWgG9WRqch5oInBRXTEXiOQjWrVbEvvNyAw8tYVx6uBsU/
qvxJ+dLCi8d2VuHhPTi2MJZy8AQG0fo6HN4q/9ubyXJOuzsXplQzJOlLdtGRvI/
BrNcqw76KUwznvvJxkmuvNIXu114gWe8cc9USFlJw6tRH8dJ82gaWTTBjISaVjk2/umQ=
Provide the PLAINTEXT output (not Base64).
Why are we doing this?
Understanding the basics of Cryptography can help in ensuring that you and your companies stay safe
from potential attacks! Using encryption on especially sensitive information is extremely important,
and understanding the basics of some of the existing cryptographic methods can help you make more
informed decisions on products for yourself and your company. Would you rather have an AES 256
encryption? Or maybe you really need RSA 2048? Do you need a symmetric key algorithm… or an
asymmetric? What level of encryption… Does the level of encryption matter.
Learning Objectives
This assignment makes use of multiple course objectives
• Implement elementary encryption
