Question

The Caesar Cipher has 25 different shifts to try.
How many possibilities are there to try in a random substitution cipher?

a) 26 b) 26 × 25 c) 26 × 25 × 24 ×···× 3 × 2 x 1 d) 2626

Answer 1

Answer:

The answer is C) 26 * 25 * 24 * ... * 3 * 2 * 1

Explanation:

For a random substitution cipher the number of possibilities is gotten from calculating 26! (Factorial of 26). Permutation is the operation performed to get the number of possibilities. Permutation is the act of arranging or rearranging the member of a set in order.

The key is 26 letters long and each plaintext letter maps to a different random ciphertext letter.

The total number of possibilities = 26! = $4 * 10^{26}$ keys.