Secret facts & stats

Question 1

In a Caesar cipher with a shift of 3, what does the letter A become?

Accepted Answer

D. A Caesar cipher shifts each letter a fixed number of places, so with a shift of 3, A becomes D.

Question 2

Which carved stone helped scholars decipher Egyptian hieroglyphs?

Accepted Answer

The Rosetta Stone. The Rosetta Stone carries the same decree in hieroglyphs, Demotic and Greek, which unlocked hieroglyphs.

Question 3

By how many letters does the ROT13 cipher shift each letter?

Accepted Answer

13. ROT13 shifts letters 13 places; applying it twice returns the original text in a 26-letter alphabet.

Question 4

In cryptography, what is 'plaintext'?

Accepted Answer

The original readable message. Plaintext is the readable message before encryption; the scrambled result is called ciphertext.

Question 5

Which letter is used most often in English text, a key clue in frequency analysis?

Accepted Answer

E. E is the most common letter in English, so the most frequent symbol in a simple cipher often stands for E.

Question 6

Which 9th-century Arab scholar wrote the earliest known description of frequency analysis?

Accepted Answer

Al-Kindi. Al-Kindi described breaking ciphers by counting how often letters appear in the 9th century.

Question 7

In the Atbash cipher, what does the first letter of the alphabet become?

Accepted Answer

The last letter. Atbash reverses the alphabet, so A becomes Z, B becomes Y, and so on. It was first used with Hebrew.

The basics