Key 1: EEEE

Key 2: ERTY

What are the advantages of using key 2 over key 1 and why?


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  • $\begingroup$ Do you know how the cipher works? $\endgroup$ – Randall May 30 at 3:03
  • $\begingroup$ I have only learnt the basics of it so i'm sorry if this is a stupid question. $\endgroup$ – Ewen Seck May 30 at 3:27
  • $\begingroup$ Test out examples of plaintexts against each of these keys. What do you notice? $\endgroup$ – Randall May 30 at 3:28
  • $\begingroup$ Welcome to Mathematics Stack Exchange! A quick tour will enhance your experience. Here are helpful tips to write a good question and write a good answer. For equations, use MathJax. $\endgroup$ – dantopa May 30 at 3:42

If you used the key EEEE, the cipher would not be a Vigenère. It would degenerate into an extremely weak Caesar cipher. With the key ERTY, you would get a genuine Vigenère cipher of period 4. While this is still very weak, breaking it nevertheless does require a little more work than a Caesar cipher does.


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