CS 444 Networks Security
Assignment1: Crypto
Note1: Use the programming language YOU LIKE and the
LIBRARIES you want to accomplish the required tasks.
Note2: You should submit your work to f.abuhjeela@gmail.com and
moealsaleh@gmail.com ; the subject MUST be “CS444 Assignment1”.
You MUST include two attachments named part1.java (or .cpp) and
part2.java (or .cpp).
Note3: Each group must have only ONE submission that includes all the
group names, their serial numbers, and student number, as the
following:
Name
serial number
student number
Note4: Each group MUST see Fatima to discuss their solution with her.
ALL group members MUST show up. If you don’t show up you will get
ZERO.
Note5: Your code MUST be FULLY DOCUMENTED/COMMENTED.
Note6: The submission due date is March 24th. NO LATE
SUBMISSIONS will be considered for whatever reasons.
Part I: Caesar Cipher
Implement the Caesar Cipher you learned in the class. Your implementation
should be restricted to the following specifications:
1- The character representation should be in ASCII representation.
2- Your implementation should have the following functions:
/* this function takes a string of characters in a plaintext
and an integer key and returns a string of characters in
ciphertext after applying the cesaer cipher algorithm
*/
string Encrypt(string plaintxt, int key);
/* this function takes a string of characters in a ciphertext
and an integer key and returns a string of characters in
plaintext after applying the cesaer cipher algorithm
*/
string Decrypt(string ciphertxt, int key);
/* this function prints the hexadecimal value of a string */
void PrintHexVal(string str);
3- You should implement the circular implementation of cesaer cipher.
For example 125 + 3 = 0.
4- You should have a testing part to show the correctness of your
implementation.
Part II: DES Usage:
 Write code that uses the DES algorithm. Your implementation should
have three functions: GenerateKey, Encrypt, Decrypt, and
PrintHexVal.
1- The GenerateKey function should generate the secret key to be
used in the DES algorithm.
2- The Encrypt function will take a plaintext and the generated
key as inputs and encrypts the plaintext using the DES
algorithm and the key. This function returns the ciphertext.
3- The Decrypt function will take a ciphertext and the generated
key as inputs and decrypts the ciphertext using the DES
algorithm and the key. This function returns the plaintext.
4- The PrintHexVal takes a string as input and prints its
hexadecimal representation of it.
 You should have a testing part to show the correctness of your
implementation