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📘 At the login box, the password begins a journey

You are at the login box, and your password is about to become a comparison value, not a readable database entry. The server should hash it, store the verifier, and discard the original.

3
lessons
~15 min
to learn
Adults
level
Start the course →

What you’ll learn

  1. From password to verifierExplain why password systems store a one-way verifier rather than a readable password, and distinguish hashing from encryption.A password becomes a repeatable comparison value, not a recoverable copy. The verifier can check a login without keeping the original secret in ordinary storage.
  2. Salt and deliberate costShow how salts prevent precomputed reuse and how tunable time and memory costs slow offline guessing.A unique salt makes each record its own problem, while a deliberately expensive password function makes each candidate guess consume meaningful resources.
  3. Verification and choosing a schemeTrace a login check, compare modern password-hashing families, and explain how systems upgrade old records.The server repeats the recorded recipe, compares the result, and can rehash after a successful login. Algorithm choice, parameters, and the surrounding login system all matter.

Questions this course answers

Why is a unique salt stored with each password hash?

A per-record salt prevents one precomputed digest from matching every account that chose the same password; it is stored so the verifier can repeat the calculation.

Put the main password-verification steps in order.

The server must know the record settings before it can reproduce the derivation, and the comparison comes only after the new value has been calculated.

Match each term to the job it performs.

These terms describe different parts of password storage: uniqueness, work settings, and named derivation families.

In your own words, why is a fast ordinary hash a poor password-storage choice?

Once an attacker has the stored records, they can guess offline without triggering the real service. Deliberate cost reduces the number of guesses their hardware can test per unit time.

Grounded in trusted sources

  • National Institute of Standards and Technology, Digital Identity Guidelines: Authentication and Lifecycle Management, SP 800-63B, section 5.1.1.2 — https://pages.nist.gov/800-63-3/sp800-63b.html
  • OWASP, Password Storage Cheat Sheet — https://cheatsheetseries.owasp.org/cheatsheets/Password_Storage_Cheat_Sheet.html
  • Biryukov, Dinu, Khovratovich and Josefsson, RFC 9106: Argon2 Memory-Hard Function for Password Hashing and Proof-of-Work Applications — https://www.rfc-editor.org/rfc/rfc9106.html
  • Moriarty, RFC 8018: PKCS #5: Password-Based Cryptography Specification Version 2.1 — https://www.rfc-editor.org/rfc/rfc8018.html

Every Wunder lesson is built from real, reputable sources — never invented.

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