Question 1

True or false: RSA can be used for both encryption and digital signatures with the same key pair.

Accepted Answer

True. RSA supports both functions: encrypt with public key, decrypt with private; sign with private, verify with public. This dual use is a key feature.

Question 2

True or false: RSA's security relies on the fact that factoring large semiprimes is computationally hard for classical computers.

Accepted Answer

True. Yes, the security of RSA is directly based on the difficulty of factoring the product of two large primes—a problem that remains hard with classical algorithms.

Question 3

True or false: RSA encryption is faster than AES encryption for large messages when using the same key size.

Accepted Answer

False. False. RSA is thousands of times slower than AES for bulk data. In practice, RSA is only used to encrypt symmetric keys.

Question 4

True or false: If an attacker steals your RSA private key, they can decrypt past messages encrypted with your public key—but not future ones.

Accepted Answer

False. False. With the private key, they can decrypt any message encrypted with the corresponding public key, past or future, unless perfect forward secrecy is used.

Question 5

True or false: RSA is vulnerable to a chosen-ciphertext attack if padding like OAEP is not used.

Accepted Answer

True. True. Without proper padding (e.g., OAEP), RSA is malleable and can be broken via chosen-ciphertext attacks, as shown by Bleichenbacher.

Question 6

True or false: RSA keys are generated by picking two random primes and multiplying them; the public exponent must always be a prime number.

Accepted Answer

False. The public exponent (commonly 65537) does not have to be prime—it just needs to be coprime with phi(n). 65537 is chosen for efficiency, not primality necessity.

Question 7

True or false: The RSA algorithm was publicly invented in 1977 by Rivest, Shamir, and Adleman—but a British intelligence agency had secretly discovered it earlier.

Accepted Answer

True. True. In 1973, Clifford Cocks at GCHQ invented an equivalent scheme, but it was classified until 1997.

Question 8

True or false: A 2048-bit RSA key is considered secure today partly because quantum computers cannot break it any faster than classical ones.

Accepted Answer

True. Actually, quantum computers using Shor's algorithm can break RSA of any size in polynomial time. This statement is false because quantum attacks are far faster.

RSA cryptography Trivia Questions