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Global Accelerated Learning • Est. 1999
Glossary Term Key Stretching

Training Camp • Cybersecurity Glossary

What is Key Stretching?

Key stretching repeatedly applies a costly function to weak secrets via PBKDF2, bcrypt, scrypt, or Argon2, slowing brute-force attacks on passwords.

Glossary > Cryptography & PKI > Key Stretching

Understanding Key Stretching

Key stretching is a cryptographic technique that strengthens weak or low-entropy secrets, such as passwords, by repeatedly applying a computationally expensive function to derive the final key. Algorithms like PBKDF2, bcrypt, scrypt, and Argon2 deliberately increase the time and resources needed per guess, slowing brute-force and dictionary attacks. Combined with a unique random salt, key stretching makes precomputed and rainbow-table attacks impractical against stored password hashes.

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