MD5 Is Broken — Stop Using It for Passwords (Use SHA256 Instead)
MD5 Is Broken — Stop Using It for Passwords (Use SHA256 Instead) MD5 was invented in 1991. It's 2026, yet I still see developers using MD5 for password hashing in production systems. Let’s break down why this is dangerous and what you should use instead. What Is a Hash Function? A hash function takes any input and produces a fixed-length output called a digest or hash . It is a one-way function , meaning you cannot reverse it to get the original input. Example: ```text id="hash1" Input: "password123" MD5: 482c811da5d5b4bc6d497ffa98491e38 SHA256: ef92b778bafe771e89245b89ecbc08a44a4e166c06659911881f383d4473e94f Even a small input change completely changes the output. --- # Why MD5 Is Broken MD5 generates a **128-bit hash**, which was considered secure decades ago. Today, it's extremely weak. Modern GPUs can compute **billions of MD5 hashes per second**, making brute-force attacks trivial. --- ## The Rainbow Table Problem Attackers use precomputed databases called **rainbow tables**. These tables map common passwords → their hash values. So if you hash: ```text "password123" → MD5 → known value An attacker can instantly look it up. Collision Vulnerabilities Researchers have demonstrated that two different inputs can produce the same MD5 hash . This breaks the core security guarantee of hash functions. SHA256 — The Better Choice SHA256 produces a 256-bit hash and is part of the SHA-2 family. It is currently considered cryptographically secure. Example: ```text id="sha1" "hello" → 2cf24dba5fb0a30e26e83b2ac5b9e29e1b161e5c1fa7425e73043362938b9824 Even tiny changes completely change the output: ```text "hello" → 2cf24dba... "Hello" → 185f8db3... But Wait — Don’t Use SHA256 for Passwords Either This is where many developers make a mistake. SHA256 is not suitable for password hashing . Why? Because it is too fast . Fast hashing allows attackers to brute-force passwords quickly using GPUs. What You Should Use Instead For password storage, use: bcrypt scrypt Argon2 (recommended