CSIS 463 – Modern Cryptography |Yones Azzab| RSA Public-Key Encryption and Signature Lab Liberty University

CSIS 463 – Modern Cryptography Yones Azzab RSA
Public-Key Encryption and Signature Lab Liberty
University



RSA Public-Key Encryption and Signature Lab


Yones Azzab


CSIS 463_B01

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Introduction


The pre-built Ubuntu image and instructions from SEED Labs are used in this experiment. The

"RSA Public-Key Encryption and Signature Lab" is the specific assignment. Rivest, Shamir, and

Adleman, or RSA, invented public-key cryptosystems and is still in use today. The RSA asymmetric

algorithm produces a key value pair consisting of the public and private keys in addition to two huge,

random prime numbers. I have a better knowledge of the operation of the RSA algorithm and the public-

private key paradigm in cryptosystems as a result of doing this lab. Digital signatures and

encryption/decryption were introduced at the lab.


The SEED Labs Ubuntu 24.04 image and Oracle VirtualBox were the system requirements for

this lab. The lab was finished using a combination of Python and C programming languages. Additionally,

the lab makes use of the BIGNUMs API and OpenSSL for the various programs that must be developed.

Unlike many cryptography labs that rely on a GUI or CLI tool to carry out tasks, this lab largely relies on

programming in C utilizing the OpenSSL and BIGNUMs API.




Method


There were six tasks in this lab to be completed. I described in detail how I go about finishing

each assignment. The creation of a C program and the use of a private or public key or certificate were

prerequisites for each task.


Task 1


I started by creating a directory using mkdir and then I used vi to build a C file from the code

that was given in the first task. Then I used gcc and the crypto library to compile the code using the

following code:


Gcc -o task1 task1.c -lcrypto

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I was able to become acquainted with BIGNUMs and OpenSSL as a result. I then ran the following code

to obtain the private key:

./task1


Task 2


Encrypting the message "A top secret!" was necessary for the second job. To convert ASCII to

hex, the lab provides a Python tool. I used this command to convert the hex to a BIGNUM in my C

program. I used Python to produce the hex first:

Python3 -c ‘print(b“A top secret!”.hex())’


Since I was using Python3, I had to do some searching to figure out how to use the hex. I used a guide I

found on stackoverflow (Python 3 String to Hex, n.d.) to assist me with this part. Then I used gcc and

the crypto library to compile the code and ran the output once again. This resulted in an encrypted and

decrypted message.


Task 3


The only difference between the third task and the second one was that in this one the program

created for the second task required encryption. This was done using the vi function to edit the code

from the last task. I compiled and ran the code to get the decrypted message. I then used Python to

translate the decrypted message back to ASCII using the following command:

Python3 -c ‘print(b”A top secret!”.hex())’


Task 4


Beyond the encryption and decryption of the previous processes, there was more to the fourth

task. The message has to be signed in order to complete this task. First, I used Python to produce hex

from the provided value: