🔑Pre-Shared Key

NEW

Also known as: PSK

A secret key shared between parties in advance for authentication or encryption.

DESCRIPTION

A pre-shared key (PSK) is a secret established out-of-band that authenticates or encrypts communications like TLS-PSK, WPA-PSK, and VPNs. PSKs reduce complexity versus certificates but require secure distribution and rotation. They are suitable for constrained environments and device provisioning. Security depends on entropy, storage, and management practices. Standards define PSK-based ciphersuites and protocols.

ALTERNATIVE DEFINITIONS

Wikipedia

In cryptography, a pre-shared key (PSK) is a shared secret which was previously shared between the two parties using some secure channel before it needs to be used.

Defines PSK and emphasizes prior secure sharing.

Source

IETF RFC 4279

This document describes the use of pre-shared key (PSK) for the TLS protocol to provide mutual authentication between client and server.

Introduces TLS-PSK use for mutual authentication.

Source

IEEE 802.11i

802.11i defines mechanisms including pre-shared key modes for robust wireless network security.

Places PSK within Wi‑Fi security standards.

Source

RELATED TERMS

TLS-PSK WPA-PSK Key Exchange Certificate Mutual Authentication IKE Virtual Private Network Key Derivation Function

COMPETING TERMS

Asymmetric Encryption Diffie–Hellman Key Exchange

RELATIONS

• Broader: Key

KNOWLEDGE AREAS

Data Security Infrastructure Software Engineering

TARGET AUDIENCE

Security Architect Cybersecurity Engineer Chief Information Security Officer DevOps Engineer Cloud Architect Software Developer

EXTERNAL SOURCES

• Wikipedia - Pre-shared key
• IETF - TLS PSK ciphersuites specification
• NIST - IPsec VPN deployment guidance
• Wi‑Fi Alliance - Wi‑Fi security modes including PSK

TOP QUESTIONS

When should a Pre-Shared Key be used?

Use PSKs for constrained environments, device provisioning, or when PKI is impractical. Ensure secure distribution and rotation.

Category: Opinion

What are risks of using Pre-Shared Keys?

Shared secrets can leak, be reused across devices, or have low entropy. Poor rotation policies increase compromise impact.

Category: Risks

How are Pre-Shared Keys distributed securely?

Use secure channels, hardware tokens, or out-of-band methods; avoid plaintext email and ensure audit trails.

Category: Best-Practices

What standards define PSK usage?

IETF RFCs define TLS-PSK; IEEE 802.11i covers Wi‑Fi PSK; IPsec supports PSK authentication.

Category: Overview

How strong should a Pre-Shared Key be?

Use high-entropy keys, ideally generated randomly and stored securely with access controls.

Category: Requirements

How do PSKs compare to certificates?

PSKs are simpler but harder to manage at scale; certificates support rotation, revocation, and identity binding via PKI.

Category: Distinction

How to manage PSK rotation?

Automate rotation with versioned secrets, stagger rollouts, and validate connectivity before deprecating old keys.

Category: Management

What is WPA-PSK?

A Wi‑Fi mode where a shared passphrase derives keys for authentication and encryption without enterprise authentication servers.

Category: Example

How to monitor PSK usage?

Track access logs, failed authentications, and unusual connection patterns; enforce alerting and periodic key audits.

Category: Observability