thinQmaster Virtual testing partner Adaptive practice exams that find your weak spots and drill them. Every answer explained. From $69
Enroll

thinQmaster

Find your exam

Five questions free, before you decide.

Step 1 · choose a vendor

In one of our camps? Your practice exams come with the tuition — they are on your study page already.

Security Fundamentals & Crypto · Foundational

Key Stretching

Technique that makes a weak key or password more resistant to brute force by applying many computational rounds.

Definition

Key stretching repeatedly processes the input or uses memory-hard functions so each guess costs significant time or memory. Common algorithms are PBKDF2, bcrypt, scrypt, and Argon2. It is the standard approach for password storage and password-based key derivation.

Example

A Wi-Fi WPA2 passphrase is stretched with 4,096 iterations of PBKDF2 to create the pairwise master key.

Exam tip

Security+ lists PBKDF2 and bcrypt as key stretching examples.

Related terms