16-page4 - “Encoding E with key S” means converting...

Info icon This preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
Key Ciphers • A better method is to use multiple translation systems, and rotate among them every letter. A convenient way to do this is to adopt a short word as a key . Let’s look at encoding the message “ET TU BRUTE” with the key “SPQR”. • The first, fifth, and ninth letters get encoded with key S, the second and sixth with key P, the third and seventh with key Q, and the fourth and eighth with key R.
Image of page 1
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: “Encoding E with key S” means converting both E and S to numbers (using A=0, B=1,. .., Z=25, so that E=4 and S=18), adding the numbers mod 26 (getting 4+18=22), and converting the result back to a letter (W). • Deciphering means fnding the key letter For each ciphertext letter and subtracting it to get the plaintext letter. Plaintext: ET TU BRUTE Repeated Key: SP QR SPQRS Ciphertext: WH IK TFJJW...
View Full Document

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern