Overview

Hash Course

Learn cryptographic hashes from first principles: digests, algorithms, integrity checks, and common mistakes.

This course teaches cryptographic hashes as one-way digests. It is not a button-by-button walkthrough of a hash generator. You will learn what a hash is, how it differs from encryption and encoding, which algorithms developers still encounter, and how to use hashes safely in real workflows.

Who this course is for

  • Backend and full-stack developers verifying downloads, configs, or API payloads
  • Engineers debugging cache keys, ETag values, or build artifact checksums
  • Anyone who has compared two hash strings and wondered whether the comparison proves anything meaningful

What you will learn

  1. What a hash produces and why it is deterministic
  2. How hashing differs from encryption and from Base64-style encoding
  3. When MD5, SHA-1, and SHA-256/384/512 are appropriate
  4. Common mistakes such as storing passwords with plain MD5
  5. A practical workflow for integrity checks and mismatch debugging

Use the related Hash Generator to experiment with examples, but remember: a matching hash proves the same bytes were hashed with the same algorithm—it does not prove trust by itself.

Start lesson 1
Hash vs Encryption vs EncodingUnderstand when data should be hashed, encrypted, or encoded, and why these mechanisms are not interchangeable.JWT vs Session AuthenticationCompare JWT-based authentication and server-side sessions for web apps, APIs, revocation, scalability, and debugging.Password Rules That Make Systems Less SecureSome password policies look strict but push users toward predictable patterns, reuse, and unsafe workarounds.