Psk

PSK, or phase shift keying, is a family of digital modulation schemes in which the information is conveyed by varying the phase of a carrier signal. Common variants include binary phase shift keying (BPSK), which uses two phases, and quadrature phase shift keying (QPSK), which uses four phases. Higher-order PSK, such as 8-PSK or 16-PSK, increases spectral efficiency by using more phase states but is more sensitive to noise and phase error. PSK signals are typically demodulated with coherent detection that requires a reference carrier phase. The technique is widely used in radio frequency communications, including satellite links, cellular networks, and various wireless standards, due to its balance of robustness and efficiency.

PSK also stands for pre-shared key, a shared secret used to authenticate communicating parties in cryptographic protocols. In network security, a PSK is configured in advance and used by clients and servers to derive session keys for encryption and integrity. It is common in Wi-Fi networks secured with WPA-PSK or WPA2-PSK and in certain VPN and encrypted-tunnel configurations. While simple to deploy, PSK-based schemes rely on secure key distribution and selection of long, random passphrases. Weak or reused keys enable offline dictionary or brute-force attacks and can compromise network security; for larger deployments or where strong identity assurance is required, certificates or 802.1X-based approaches are preferred.

In other contexts, PSK may have different meanings, but phase shift keying and pre-shared key are the two most widely encountered definitions.