Encoding & Cryptography
Almost every mistake in this category comes from vocabulary: treating Base64 as encryption, treating MD5 as encryption, treating "encrypt" as one action rather than three different problems. Encoding answers "how do I turn bytes into text", hashing answers "are these the same thing", encryption answers "can someone else read it".
Once those are separated, what remains is parameter choice — which AES mode, which password hash, how long a key. Those have definite answers, and the guides give the default plus the reason.
- Base64 Is Not Encryption: When to Use ItBase64 is a transport encoding with zero secrecy. Here is what it actually guarantees, why it inflates data by 33%, where it is genuinely the right tool, and how it differs from hashing and encryption.
- Password Hashing: Why SHA-256 Is the Wrong ChoiceA modern GPU tries billions of SHA-256 hashes per second. Passwords need a deliberately slow hash, not a fast one. Here is how bcrypt, scrypt and Argon2 differ, what the cost factor controls, and why salts are not enough.
- Symmetric vs Asymmetric Encryption: Which to UseAES and RSA are not old and new versions of the same thing. Symmetric encrypts the data, asymmetric hands over the key. Which AES mode to pick, why ECB must go, and what "hybrid encryption" actually means.
- UUID v4 vs v7: Choosing a Primary KeyBoth are 128 bits and both are unique. The difference is what the first bits contain, which decides whether your database inserts append or scatter across the index.
- What Is a JWT? Structure, Signing, and DebuggingA JWT is three Base64URL segments joined by dots. Here is what each part contains, why the payload is readable by anyone, what the signature actually proves, and the three mistakes that cause most auth bugs.