RSA Cryptography: Keys, Operations, and Security

All flashcards

What is an asymmetric cryptosystem?

A cryptosystem using mathematically related public and private keys for different operations; the public key may be shared, while the private key is kept secret.

What does RSA stand for?

RSA takes its name from Ron Rivest, Adi Shamir, and Leonard Adleman, who publicly described the system in 1977.

What is the integer factorization problem?

The problem of recovering the prime factors of a composite integer, such as finding $p$ and $q$ from $n=pq$.

What was Clifford Cocks’s role in the history of RSA?

Cocks developed a similar system secretly at GCHQ in 1973; the work was declassified in 1997.

Why use RSA in a hybrid cryptosystem?

RSA can protect a short symmetric key, while a faster symmetric cipher encrypts larger amounts of data.

Quiz questions

1. Which scheme is recommended for RSA encryption in new applications?Answer: RSAES-OAEP, which uses randomized encoding for encryption.
2. Which scheme is designed for RSA digital signatures?Answer: RSA-PSS, a probabilistic signature scheme.
3. What security weakness results from raw RSA encryption being deterministic?Answer: An observer can compare repeated ciphertexts and test guesses about likely plaintexts.
4. What is the main performance benefit of using the Chinese remainder theorem for RSA decryption?Answer: It replaces one large modular exponentiation with operations using smaller moduli.
5. What can a padding-oracle attack exploit?Answer: Responses that reveal whether decrypted ciphertext passed padding validation.