Question 1

What is the Caesar cipher?

Accepted Answer

The Caesar cipher is one of the oldest known encryption techniques, named after Julius Caesar who used it for military communications. It works by shifting each letter in the plaintext by a fixed number of positions in the alphabet. For example, with a shift of 3, A becomes D, B becomes E, and so on.

Question 2

How do I decrypt a Caesar cipher without knowing the key?

Accepted Answer

There are several methods: 1) Brute force all 26 possible shifts and look for readable text. 2) Use frequency analysis - in English, E is the most common letter, so the most frequent letter in the ciphertext likely represents E. 3) Look for common patterns like single-letter words (A, I) or common short words.

Question 3

What is ROT13 and how does it relate to Caesar cipher?

Accepted Answer

ROT13 is a specific Caesar cipher with a shift of 13. Since the English alphabet has 26 letters, applying ROT13 twice returns the original text. This makes it symmetric - the same operation encrypts and decrypts. ROT13 is often used to hide spoilers or puzzle answers online.

Question 4

How secure is the Caesar cipher?

Accepted Answer

The Caesar cipher is not secure by modern standards. With only 26 possible keys (shifts), it can be broken in seconds by trying all possibilities. It is useful for learning about cryptography and obfuscating casual text, but should never be used for protecting sensitive information.

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