Key Derivation Function

Definitions

1. A function that derives one or more cryptographic keys from a secret value (password, passphrase). Password-hashing KDFs (bcrypt, scrypt, Argon2) are intentionally slow and memory-hard to resist brute-force attacks. Argon2id won the Password Hashing Competition and is the current recommendation. Never use SHA-256 or MD5 for password storage.

   In plain English: A deliberately slow hashing function for passwords that makes brute-force cracking extremely expensive.

   Example: "Hash passwords with Argon2id, not SHA-256 — Argon2's memory-hardness makes GPU brute-force attacks impractical."

Related Terms

• Brute Force
• Steganography
• PKI
• Homomorphic Encryption
• Post-Quantum Cryptography
• Cleartext
• Crypto Agility
• Cryptographic Hash
• Entropy Analysis
• MD5
• PBKDF2
• Collision Resistance
• Message Digest
• Password Salt
• Post-Quantum