Cryptography quiz

More questions about Cryptography

These visible examples show the question style. LearnClash turns the full topic into ranked duels and spaced repetition.

1. 1 Easy

   Which kind of numbers are multiplied to make an RSA key?

   Answer: Prime numbers

   Why: Multiplying two huge primes is easy, but splitting their product back into those primes is hard enough to keep RSA safe.

2. 2 Medium

   Which cipher was proven unbreakable if used correctly?

   Answer: One-time pad

   Why: The catch: the key must be truly random, at least as long as the message, and never used twice.

3. 3 Hard

   About how many tries find a collision in a 128-bit hash?

   Answer: 2⁶⁴

   Why: It is the birthday paradox at work: among just 23 people, there is about a 50% chance that two share a birthday.

4. 4 Easy

   What does the padlock next to a web address show?

   Answer: Encrypted connection

   Why: Nearly all phishing sites use HTTPS as well, so a scam page can show the same padlock as your bank.

5. 5 Medium

   How can two strangers agree on a secret key without sending it?

   Answer: Diffie-Hellman

   Why: Only in-between values travel in public, and each side mixes them with its own secret number to arrive at the same key.

6. 6 Hard

   What keeps past chats safe even if a server's key is stolen later?

   Answer: Forward secrecy

   Why: Signal gets it from its Double Ratchet algorithm, which gives every single message its own fresh key.