use JAVA to decipher the ciphertext and use Index of coincidence to reduce key period possibilities

the third picture is vigenereCipher

LAB ACTIVITIES: To get a deep understanding of Vigenere cipher, try to encrypt a plaintext message "in God we trust. Al others, we virus scan. with the keyword vigenere In the following table, the first row is the plaintext, the second row is the repeating keywords, and the third row is the ciphertext according to Vigenere cipher. Did you get the correct ciphertext? The following is the main work of this lab. The attached fle VigenereCipher.bxt is a sample of ciphertext generated using a Vigenere cipher of unknown key period. White a computer program with a programming language (e.g, Java) to decipher the ciphertext. You can try the following methodology 1. To decipher the Vigenere ciphertext, first determine the possible key period d. We can use index of coincidence (I.C) to reduce key period possibilities a) Caloulated from the provided ciphertext, an estimate of L.C. can be obtained using the following equation: N(N-I) C33873 Lab Envcise where N is the total number of leters in the cipertext, no is the number of occurrences of letter A, n is the number of occurrences of letter B, na is the number of occurrences of letter C, and so on b) On the other hand, for a language of an alphabet of L leters,given a cipher of period d, the expected value of LC. can be calculated by 066+ For example, for English ciphertext with L-26, typical LC. vailues indlude: Table 1. Typical I.C. Values with Key Period d LC. Values 0.066 0.052 0.047 0.044 0.043 Key Period d c) Find the LC. value(s) in Table 1 that are closest to the LC. value calculated by Equation (1). The comresponding valuels) of d are the most likely key periods).Note that you may need to choose at least two possible values of d since there may not be an exact match