Security & Privacy
How to Verify a SHA-256 Checksum on Windows, Mac and Linux
The exact commands to check a download's SHA-256 checksum on Windows, macOS and Linux, how to compare it without eyeballing 64 characters, and what a match proves.
Security & Privacy
How hashing, passwords and card number checks actually work, based on current standards and guidance.
Security & Privacy
Passkeys vs Passwords: How Passkeys Work
A passkey replaces the secret you type with a key pair: the site keeps a public key, your device signs a one-time challenge. Here's why that stops phishing.
Security & Privacy
How Credit Card Numbers Work: The Luhn Algorithm
Card numbers carry their own typo check. Here's how the Luhn algorithm works step by step, what the leading digits mean, and what a passing check can't tell you.
Security & Privacy
Hashing vs Encryption vs Encoding: The Difference
Encoding can be reversed by anyone, hashing can't be reversed at all, and encryption needs a key. Here's one message run through all three, and how to choose.
Security & Privacy
How Long Should a Password Be? What NIST Now Says
NIST's current guidelines call for at least 15 characters, no forced complexity and no scheduled changes. Here's why length wins, with real numbers for passwords and passphrases.
Security & Privacy
MD5 vs SHA-256 vs bcrypt: Which Hash to Use
MD5, SHA-256 and bcrypt solve different problems. Here's which one fits checksums, signatures and password storage, and why speed decides it.