Which of the following can use a PSK?
A. Asymmetric encryption
On the surface, this 8 word question seems rather simplistic. However, unless you've spent time with the material, all of the acronyms will make it very difficult. PSK can mean many things, but in the context of security, and with all of the answers relating to cryptography, it refers to a pre-shared key.
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CompTIA Security+: Get Certified Get Ahead: SY0-201 Study Guide
The correct answer is C. A trusted platform module (TPM) uses a pre-shared key (PSK) to encrypt and decrypt data such as entire disks. (Microsoft uses this with BitLocker.) Symmetric encryption uses a single key to both encrypt and decrypt while asymmetric encryption uses two keys—public and private. Both PGP (Pretty Good Privacy) and PKI (Public Key Infrastructure) use asymmetric encryption.
Good luck on the exam.