Hashing vs. Encryption: When to Use SHA-256 vs. AES vs. Argon2
Learn the vital differences between cryptographic hashing and encryption. Explore SHA-256 for data integrity, AES for data confidentiality, and Argon2/bcrypt for passwords.
Core Differences at a Glance
| Feature | Hashing (SHA-256, MD5) | Encryption (AES-256, RSA) | Password Hashing (Argon2, bcrypt) |
|---|---|---|---|
| Purpose | Data integrity & checksums | Confidential data storage & transit | Secure password storage against GPUs |
| Reversibility | Irreversible (One-way) | Reversible (with decryption key) | Irreversible (Slow with work factor) |
| Output Size | Fixed (e.g. 256 bits for SHA-256) | Proportional to input size | Fixed string with salt + hash parameters |
| Speed | Fast (Hardware accelerated) | Fast (AES-NI accelerated) | Intentionally Slow (Resistant to brute force) |
Why SHA-256 Should Not Be Used Directly for Passwords
SHA-256 is designed to compute digests extremely quickly (billions of hashes per second on modern GPUs). Fast hashes make brute-force cracking trivially fast. For storing user passwords, always use slow, salted, memory-hard key derivation algorithms such as Argon2id, bcrypt, or PBKDF2.