Hashing vs Encryption
Hashing and encryption are both cryptographic, but they serve opposite goals. One is a reversible lock for confidentiality; the other is a one-way fingerprint for integrity. Mixing them up is a common exam trap.
Last updated August 2026
| Aspect | Hashing | Encryption |
|---|---|---|
| Reversible? | No, one-way by design | Yes, two-way with the key |
| Purpose | Verify integrity, store passwords | Protect confidentiality |
| Output | Fixed-length digest | Ciphertext that scales with the input |
| Key | No key (may use a salt or an HMAC key) | Requires a key |
| CIA goal | Integrity | Confidentiality |
| Examples | SHA-256, SHA-3, MD5 (broken) | AES, RSA, ChaCha20 |
The bottom line
Encryption protects confidentiality and can be reversed with the key; hashing is a one-way fingerprint that proves integrity and cannot be reversed. Passwords should be hashed with a salt and a slow algorithm, never encrypted.
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FAQ
Can you decrypt a hash?
No. Hashing is one-way by design. Attackers can only guess inputs and compare hashes, which is why salting and slow hashes such as bcrypt, scrypt, and Argon2 matter for passwords.Why hash passwords instead of encrypting them?
Encryption is reversible, so a stolen key would expose every password. A salted one-way hash cannot be reversed, so even the provider never stores the actual password.
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