Code In Java: Vigenere Cipher Decryption Program

Your program should input the ciphertext from a file, or additionally allow the user to input from the keyboard, and then output the decrypted text. It should do this without seeking additional input or help from the user. Your program should first calculate the key length, and should then calculate all of the necessary mutual indices of coincidences to find the shift used in each key position.

In addition to the final decrypted text, please have your program also output clearly-labelled values found during your process of finding the key length, a table of values for the mutual indices of coincidence, and finally the original key and decrypted text. If you don't want these reams of information to interfere with your screen output, then save the labelled numeric information to a file, or have the program allow a "verbose" option.

Please note that the methods of cryptanalysis that we're using work well, but if the text is too short, or if the original plaintext itself varies much from standard English in its distribution of characters, or if the ciphertext was not encrypted with a vigenere cipher, then the algorithm may not always produce valid plaintext. By testing the values of the indices of coincidence and the mutual indices of coincidence, your program should give an indication to the user of whether or not you think the text was successfully decrypted. Also test your program on ciphertext that was *not* encrypted with a vigenere cipher.