Lesson 2.75: Encryption in everyday life: at rest, in transit, and hashing
Encryption turns readable data into something useless without the key. It protects data at rest (a laptop disk, a backup file) and in transit (the padlock in your browser, which is TLS). Hashing is different: it makes a fingerprint that can't be turned back into the data, used to check integrity and to store passwords. In the lab you fingerprint a confidential file, encrypt it with a passphrase, see the wrong passphrase fail and the right one work, and read the certificate a web shop uses to encrypt traffic.
16 min
You will learn to
- Tell encryption from hashing
- Explain data at rest and in transit
- Encrypt and decrypt a file with a passphrase
- Explain why the key matters more than the algorithm
- Read the main fields of a TLS certificate
Key terms
- Encryption
- Turning data into ciphertext that only someone with the key can turn back.
- Hashing
- Making a fixed-size fingerprint of data that can't be reversed.
- Data at rest
- Data stored on a disk, phone or backup.
- Data in transit
- Data moving across a network; protected by TLS on the web.
- AES
- The standard symmetric cipher: the same key encrypts and decrypts.
- Certificate
- A signed statement binding a public key to a name, used by TLS.
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