How many rounds are used in the asymmetric cipher RSA?

In RSA, the process of encryption and decryption can be considered to occur in a single round, which is why the correct answer is that RSA uses 1 round. This is fundamentally different from symmetric key algorithms that often employ multiple rounds to enhance security through repeated transformations of the data.

In RSA, the key steps involve exponentiation of the plaintext message with a public key for encryption and then exponentiation with the private key for decryption. Given its design as an asymmetric cipher, RSA operates on the premise that the two keys (public and private) yield a secure communication channel without needing rounds of processing to obscure the data.

The other choices, representing 2, 3, or 4 rounds, suggest a layered approach typical of symmetric encryption methods where multiple applications of cryptographic transformations are essential for breaking down information and minimizing patterns. However, in the case of RSA, the inherent security mechanism relies not on multiple rounds but rather on the mathematical properties of large prime factorization, making one round sufficient for its operations.