Asymmetric encryption is a method that uses a mathematically linked pair of keys, a public key that can be shared freely and a private key that stays secret. Data locked with the public key can only be opened with the matching private key. This design solves the problem that plagues symmetric systems, because anyone can encrypt a message to you using your public key, yet only you can read it, with no shared secret exchanged in advance.
RSA, elliptic curve cryptography (ECC), and Diffie-Hellman for key agreement are the names to know. The tradeoff is performance, since these operations run far slower than symmetric ones. That is why real systems rarely encrypt bulk data this way. Instead they use hybrid encryption, where asymmetric cryptography safely exchanges a random symmetric key and that faster key then protects the actual traffic. TLS works exactly like this, and understanding that pattern answers a surprising number of exam questions.
Why does asymmetric encryption matter for the CISSP exam?
It is covered in Domain 3: Security Architecture and Engineering, worth 13 percent of the exam. Know the key pair relationship, the common algorithms, the performance tradeoff, and how hybrid encryption ties both worlds together.
See NIST SP 800-57.