PLEASE HELP SOLVE PROBLEM 2 ONLY
Problem 1. Write computer programs for the Substitution Cipher based on Zn, which is cor- responding to 26 alphabetic characters (0 - 25), space (26), and ", " (27) "." (28). The key is a random permutation 7 on Z29. Write down encryption and decryption programs. For the encryption, the plaintext and the key need to be input. The out put will be the ciphertext. Select a paragraph of text (I don't think any two people will choose a same paragraph if they choose independently) and encrypt it using your encryption algorithm. Then use your decryption program to check the correctness. You can use Java, C or other computer languages. Record your plaintext, ciphertext and the key # in your answer sheet. Problem 2. Write computer programs for the Permutation Cipher based on Z2g as in Problem 1. In encryption program, the inputs are a value of m (the size of permutation), a permutation as the key and the plaintext, and the output is the ciphertext. Write the decryption program accordingly. Try your programs by some text. Note that since 1 m and the length of plaintext is not fixed, paddings might be added to the end of plaintext by the program. You may think about what kind padding is better for the security and design your paddings. Problem 3. Write an algorithm to perform known-plaintext attack on Permutation Cipher. This algorithm can be used to determine the length of the permutation m and the key permutation. Use this algorithm to attack the system in Problem 2: by inputting a plaintext and the according cipher text from Problem 2, your program should output the value of m and the permutation (the key). Problem 1. Write computer programs for the Substitution Cipher based on Zn, which is cor- responding to 26 alphabetic characters (0 - 25), space (26), and ", " (27) "." (28). The key is a random permutation 7 on Z29. Write down encryption and decryption programs. For the encryption, the plaintext and the key need to be input. The out put will be the ciphertext. Select a paragraph of text (I don't think any two people will choose a same paragraph if they choose independently) and encrypt it using your encryption algorithm. Then use your decryption program to check the correctness. You can use Java, C or other computer languages. Record your plaintext, ciphertext and the key # in your answer sheet. Problem 2. Write computer programs for the Permutation Cipher based on Z2g as in Problem 1. In encryption program, the inputs are a value of m (the size of permutation), a permutation as the key and the plaintext, and the output is the ciphertext. Write the decryption program accordingly. Try your programs by some text. Note that since 1 m and the length of plaintext is not fixed, paddings might be added to the end of plaintext by the program. You may think about what kind padding is better for the security and design your paddings. Problem 3. Write an algorithm to perform known-plaintext attack on Permutation Cipher. This algorithm can be used to determine the length of the permutation m and the key permutation. Use this algorithm to attack the system in Problem 2: by inputting a plaintext and the according cipher text from Problem 2, your program should output the value of m and the permutation (the key)
