Question

What is the rule for encryption in playfair cipher if the letters in a pair appear in same row?

(a) they are replaced by the letter appearing immediately below them respectively

(b) they are replaced by the letter appearing immediately right to them respectively

(c) they are replaced by the letter at the corner of the row

(d) that pair is neglected

I had been asked this question in an interview for internship.

Question is taken from Cryptography in division Cryptography of Data Structures & Algorithms II

Answer 1

Right answer is (b) they are replaced by the letter appearing immediately right to them respectively

Best explanation: If the letters in a pair appear in same row then they are replaced by the letters appearing immediately right to them respectively. If the element to be replaced appears at the corner of the row then we wrap around to the left side of that row.