Question

Which of the following is reciprocal cipher?

(a) vigenere cipher

(b) autokey cipher

(c) running key cipher

(d) beaufort cipher

This question was posed to me in an internship interview.

My doubt is from Cryptography in portion Cryptography of Data Structures & Algorithms II

Answer 1

Correct choice is (d) beaufort cipher

Explanation: A reciprocal cipher is a cipher in which if we try to encrypt the cipher text (using the same cipher) then we gets the plain text as a result. In other words, the process of decryption and encryption is exactly the same.