Homework4.pdf - Adobe Acrobat Pro DC X File Edit View Window Help Home Tools Homework4.pdf Sign In A W 1 2 1 2 to Share Search tools Lo Create PDF Combine Files Edit PDF 4. You are performing a Friedman attack on a Vigenere cipher (unrelated to the Vi- Po Export PDF genere cipher in the previous question). You have already determined that this ED Organize Pages Vigenere cipher has key length 3. If y = (yo, . .., yN-1) is a string of ciphertext of La Send for Comments NEW length N with N = 0 (mod 3), let y' = (yj, yetj, . ..,UN-j-1) be the substring of y Comment whose typical entry is yi for some i = j (mod 3). Let Et(y') be the encryption of Lu Fill & Sign Scan & OCR the string y by the shift cipher with key t for 0