What Is Encryption

In brief

Encryption as a two-way door, and the split between symmetric and asymmetric keys.

Objectives

Define encryption in one sentence
Tell symmetric from asymmetric

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.

Recap

Encryption is reversible with the right key
It protects confidentiality, not integrity