MD5 vs SHA-256
MD5
Pros
- Very fast computation
- 128-bit output — compact
- Legacy support in old systems
- Still acceptable for non-security checksums
Cons
- Collision attacks are practical since 2004
- Deprecated for all security applications
- Not suitable for signatures or password hashing
- Non-compliance with modern security standards
SHA-256
Pros
- No known practical collision attacks
- Industry standard for integrity and HMAC
- Required by most compliance frameworks
- Powers HS256 JWT signing and TLS
Cons
- Slower than MD5 (negligible for most workloads)
- 256-bit output is larger than MD5
- Not designed for password storage alone
Verdict
Never use MD5 for security — signatures, password storage, certificate fingerprints, or API key hashing. Collision attacks make MD5 unsuitable for any integrity check where an attacker controls input. Use SHA-256 for all cryptographic hashing needs: data integrity, HMAC construction, and API key fingerprinting. MD5 survives only in non-adversarial contexts like etag generation or deduplication where collision attacks are not a threat.
Related Tools
Deeper Reading
Frequently Asked Questions
Is MD5 ever safe to use?
Only for non-security checksums where attackers cannot craft colliding inputs, such as file deduplication in trusted environments.
Should I migrate existing MD5 hashes?
Yes, for any security-sensitive use. Re-hash with SHA-256 and update verification logic.