Implement a toy symmetric cryptosystem based on the following method.

a. Keys are 16-bit randomly generated values.

b. Messages are randomly generated strings with an even number of characters. (Valid characters are upper and lower case letters, as well as spaces.) One can always add a blank at the end of an odd-length string.

c. The encryption of a message M of length n (in bytes) is given by where the key K is repeated n/2 times.

d. The decryption algorithm for a ciphertext C is the same as the encryption algorithm: Implement a brute-force decryption attack for this cryptosystem and test it on randomly generated English text messages. Automate the process of detecting whether a decrypted message is English text.

Instruction:

You should use Java programming language to do this assignment.

Transcribed Image Text:

E (M) = M © (K || K || K · … ·) E (M) = M © (K || K || K · … ·)