Which encryption method employs asymmetric public key techniques and is widely used without known vulnerabilities?

The choice of RSA as the correct answer is grounded in its foundation as an asymmetric encryption method that employs public key techniques. RSA, which stands for Rivest-Shamir-Adleman (the developers' names), is renowned for its robustness and has a well-established history in securing communications.

In RSA, a pair of keys—a public key and a private key—are generated. The public key can be shared with anyone and is used for encrypting messages, while the private key is kept secret and used for decrypting those messages. This key pair system is particularly advantageous as it allows secure data exchange without needing to share the private key, minimizing risks associated with key management.

RSA is widely adopted in various security protocols, including SSL/TLS for securing web traffic and PGP for securing emails. Its ongoing use in many applications and lack of known vulnerabilities strengthen its reputation as a secure method for encryption.

Other options like AES, while secure and widely applied, use symmetric key encryption, which requires both parties to share the same key. Elliptic curve cryptography is another asymmetric option but is less recognized than RSA. Diffie-Hellman is primarily a key exchange method rather than an encryption technique, further differentiating it from the nature of RSA