Le chiffrement comme porte à double sens, et la distinction entre clés symétriques et asymétriques.
Qu'est-ce que le chiffrement
En bref
Objectifs
- Définir le chiffrement en une phrase
- Distinguer symétrique et asymétrique
Encryption turns readable data into unreadable ciphertext using a key, and — crucially — turns it back with the right key. It is a two-way door.
Symmetric vs asymmetric
With symmetric encryption, the same key locks and unlocks. With asymmetric, a public key locks and a private key unlocks — which is how TLS lets a stranger send you something only you can read.
Note
Encryption protects confidentiality: keeping data secret from anyone without the key. It says nothing about whether the data was tampered with — that is a different property.
Legal
Strong cryptography is legal to learn and use, but exporting or deploying it can carry local rules. Study it freely on your own systems.
À retenir
- Le chiffrement est réversible avec la bonne clé
- Il protège la confidentialité, pas l'intégrité