Guide
MD5 vs SHA-256 : quelle différence ?
Comprenez la différence pratique entre MD5 et SHA-256 pour choisir le bon hash.
Les deux transforment une entrée en hash de longueur fixe, mais leurs usages diffèrent. En pratique, il faut distinguer détection rapide de changement et contrôle d’intégrité plus robuste.
Quick definition of each algorithm
MD5 outputs a 128-bit hash, usually shown as 32 hex characters.
SHA-256 outputs a 256-bit hash, usually shown as 64 hex characters.
Why SHA-256 is generally preferred now
MD5 is considered cryptographically weak because collisions are practical.
SHA-256 is much harder to break, so it is preferred for modern integrity and security-sensitive workflows.
When teams still use MD5
MD5 can still appear in old systems, mirrors, or compatibility scripts.
It is often used as a quick fingerprint where security is not the primary goal.
- Legacy checksum fields in old tools.
- Fast duplicate detection in internal scripts.
- Backwards compatibility with existing APIs.
Practical rule of thumb
For new projects, pick SHA-256 unless you have a clear compatibility reason not to.
If another system forces MD5, document that decision and treat it as a legacy constraint.
How to compare outputs correctly
Hashes are exact-match values. One character difference means the inputs were different.
Make sure encoding and whitespace are consistent before deciding data changed.
Utile pour
- Choosing a hash algorithm for file verification.
- Explaining why older systems still output MD5.
- Documenting team rules for checksum workflows.
- Avoiding weak defaults in new projects.
MD5 pour la compatibilité, SHA-256 par défaut
Pour un nouveau workflow, SHA-256 est généralement le meilleur choix. Gardez MD5 uniquement pour des contraintes legacy.