# Caesar Encryption

#### mrdumb

Hello forgive me if I post it on wrong section, I would really appreciate if someone can help me solve or even give me hint about this problem.

1. Assume that we choose N (that is, K=14) as an encryption key in Caesarâ€™s cipher. What is the result Ci of the following (double) encryption

Ci = E (K,E(K, Mi))

where Mi is an arbitrary plaintext element?.

2. If at all possible, how many encryptions with key K=2 is needed before observing the same effect as in the previous example (with K=14)?

#### CRGreathouse

Forum Staff
Hello forgive me if I post it on wrong section, I would really appreciate if someone can help me solve or even give me hint about this problem.

1. Assume that we choose N (that is, K=14) as an encryption key in Caesarâ€™s cipher. What is the result Ci of the following (double) encryption

Ci = E (K,E(K, Mi))

where Mi is an arbitrary plaintext element?.
Hmm, maybe A is a shift of 0 so N is a shift of 13.

If you shift a letter forward by K, what do you get? If you shift it forward by 2K, what do you get? Try for both 13 and 14, and see what this tells you about the whole message.