Which of the following is an example of Public Key cryptography?

Public key cryptography is a type of cryptography that uses pairs of keys: a public key, which can be shared openly, and a private key, which is kept secret. The idea is that information encrypted with one key can only be decrypted by the corresponding key. The Digital Signature Standard (DSS) utilizes public key cryptography principles to create digital signatures, allowing for secure authentication and integrity verification of messages or documents. This standard ensures that signers can prove their identity while allowing others to verify that the message has not been altered.

In contrast, the Secure Sockets Layer (SSL) protocol does use public key cryptography as part of its broader functionality but is not itself an example of public key cryptography. Blowfish and AES are both symmetric key algorithms that use the same key for both encryption and decryption, which fundamentally differs from the asymmetric nature of public key cryptography. Therefore, DSS stands out as the clear example of public key cryptography among the given options.