Which cipher is an example of asymmetric key cryptography?

Asymmetric key cryptography, also known as public key cryptography, uses a pair of keys – a public key and a private key – for encryption and decryption processes. RSA, which is the correct answer, is a widely recognized example of this type of cryptography. In RSA, data encrypted with the public key can only be decrypted with the corresponding private key. This mechanism allows secure communication between parties who have not shared a secret beforehand, as the public key can be distributed openly while the private key remains confidential.

In contrast, the other options listed represent symmetric key cryptography, where the same key is used for both encryption and decryption. AES (Advanced Encryption Standard), Blowfish, and 3DES (Triple Data Encryption Standard) all rely on a single shared key that must be known by both the sender and receiver to access the encrypted information. This fundamental distinction highlights why RSA is classified as asymmetric key cryptography, distinguishing it from the symmetric algorithms.