Encryption
Encryption
- Encryption scrambles data so it can't be understood if it is intercepted.
- Readable data is plaintext; scrambled data is ciphertext.
- There are two kinds: symmetric and asymmetric.
What encryption does (and doesn't)
- Encryption uses a key to turn plaintext into ciphertext, and back again to decrypt.
- It does not stop data from being intercepted — it only stops the intercepted data from being understood.
Practice
What does encryption achieve?
Encryption scrambles data so interception is useless — it does not prevent the interception itself.
Practice
Readable data before encryption is called:
Plaintext is the readable data; ciphertext is the scrambled result.
Symmetric encryption
- Symmetric encryption uses a single key to both encrypt and decrypt.
- The sender and receiver must share this same secret key.
- The risk: the key itself could be stolen while being shared.
Practice
Symmetric encryption uses:
Symmetric uses one secret key that both sides must share — the risk is that key being stolen.
Asymmetric encryption
- Asymmetric encryption uses two keys: a public key (anyone can have it, used to encrypt) and a private key (kept secret, used to decrypt).
- Data encrypted with the public key can only be decrypted with the matching private key.
- The secret key never has to be shared, so it is safer than symmetric.
Practice
In asymmetric encryption, data is encrypted with the ____ key and decrypted with the ____ key.
The public key encrypts; only the matching private key can decrypt — so the secret key is never shared.
Practice
Why is asymmetric encryption considered safer than symmetric?
Only the public key is shared; the private key stays secret, removing the key-sharing risk.
You've got it
Key idea
- encryption makes intercepted data unreadable (it doesn't prevent interception)
- plaintext → ciphertext using a key
- symmetric = one shared key (risk: sharing it); asymmetric = public key encrypts, private key decrypts
- asymmetric is safer because the secret key is never shared