- CTF week 8 code: Integrity
- Watch the following video on Cryptography: Encryption – Cryptography – Practical TLS – YouTubeLinks to an external site.
This week we are going to do a series of exercises. You will need to include supporting images.
Exercise 1: Cryptography. Mr. Scott wants to understand what is cryptography and which part of the CIA Triad it affects.Exercise 2: Confidentiality. We have talked about the security triad several times in the course. We can encrypt data to protect it while it is in the different information states (transport, use, and storage) as we discussed with the McCumber Cube. Encryption involves taking plain text (unencrypted) and applying an encryption algorithm against it to create ciphertext. There are many algorithms that use very complex math to create the ciphertext. Let's start with some basic concepts.
Rotation or shift of characters. Sometimes known as the Caesar Cipher, If we take a plain text word like “dog” and shift/rotate 3, then the ciphertext becomes “grj”
What would “wust” become?
Several websites offer simple web-based forms to assist in encrypting and decrypting text.
Encrypt a small message (no more than a couple of words) to Mr Scott. What encryption website did you find and use?
Exercise 3: Mr Scott would like to send some encrypted messages to Dwight and Jim but he does not want them to be able to read the other person's message. Using Asymmetric encryption what keys would Mr. Scott use to accomplish this? Recall in Asymmetric encryption we have key pairs. Each person has a private and public key. You should be very specific in this scenario on which keys you are using and for what part of the message transfer (encryption or decryption).The second part of this scenario is Mr Scott wants to make absolutely sure that when he receives a message from Oscar, that is definitely came from Oscar. What keys would oscar use in his message to Mr Scott?
Exercise 4: Integrity. Sometimes when you download files from the Internet, you may want to make sure the files have not changed while they were “stored” on the website or while they were “in transit” during the download. A hash will provide some level of confidence that a file’s integrity is maintained.
I will demo how to do this during Monday's live session.
We will look at two files that have only one character that is different.
Create a file that has the following text
WUST Cyber
The second file will be
WUST Cyber!
Run a hash tool like hashdeep and compare the two hashes. Note: you do not have to use hashdeep. You can use any hashing tool that you prefer.
hashdeep: click hereLinks to an external site.
Exercise 5: NICE Challenge. Digital Duplicates.
