Summary - Crypto

Combine createHash, randomBytes and HMAC to write an encryptor.

Summary - Crypto

In this group you learned Node.js's crypto module: one-way hashes with createHash, secure random bytes with randomBytes, keyed signatures with createHmac, AES encryption with createCipheriv. Now we will combine them in an encryptor.

Structure: hash a string with createHash, generate a salt with randomBytes, sign with createHmac. We verify each tool works correctly by printing the length of its output. This is the foundation of a real authentication system: hashes give fingerprints, salts give uniqueness, HMAC gives signatures. Since output lengths are fixed, we get deterministic results when combining them.

Exercise Write an encryptor helper

Import with const crypto = require("node:crypto");. Hash with const hash = crypto.createHash("sha256").update("merhaba").digest("hex");. Generate salt with const salt = crypto.randomBytes(4).toString("hex");. Sign with const hmac = crypto.createHmac("sha256", "anahtar").update("veri").digest("hex");. Print lengths with console.log("Hash length: " + hash.length), console.log("Salt length: " + salt.length) and console.log("HMAC length: " + hmac.length).

Show example solution

const crypto = require("node:crypto");
const hash = crypto.createHash("sha256").update("merhaba").digest("hex");
const salt = crypto.randomBytes(4).toString("hex");
const hmac = crypto.createHmac("sha256", "anahtar").update("veri").digest("hex");
console.log("Hash length: " + hash.length);
console.log("Salt length: " + salt.length);
console.log("HMAC length: " + hmac.length);

Test yourself

What is the correct way to store a password safely?
```
Parola → hash → sakla
```
- Storing it as plain text
- Encoding with Base64 and storing it
- Tuz ile hash'leyip saklamak
- Only printing with console.log
Show answer

Tuz ile hash'leyip saklamak — Hashing with salt is the safest way to store.
Match each tool to its purpose

createHash

One-way hash
randomBytes

Secure random bytes
createHmac

Keyed signature
createCipheriv

Two-way encryption

Complete the createHash call

const hash = crypto.____("sha256").update("merhaba").digest("hex");

Show answer

const hash = crypto.createHash("sha256").update("merhaba").digest("hex");

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