Track 8 of 12
Cryptography in practice
What the padlock means, and where crypto goes wrong.
Intermediate 5 lessons Prerequisite: Encoding and hashes from the security track, and some comfort with the shell.
The cryptography a working person actually meets, taught by doing it rather than by proving theorems. You separate the three things people constantly confuse, work with symmetric and asymmetric keys, read a certificate and follow the chain of trust, sign a file and verify somebody else's signature, and then look at the mistakes that break real systems.
By the end, you can tell hashing from encoding from encryption, read a certificate, and verify a signature.
Lessons in this track
- 01 Hashing, encoding and encryption are three different things Hashing is one way, encoding is not secret, and encryption needs a key. See the difference in three short commands.
- 02 Symmetric and asymmetric keys One shared secret, or a pair of related keys? See how each works, and when to reach for which.
- 03 TLS and the chain of trust The padlock means more than encryption. See what a certificate says, and who vouches for it.
- 04 Signing and verifying a file A signature proves a file has not changed and came from the key holder. Sign one and check one with gpg.
- 05 Common crypto mistakes Five mistakes that keep turning up, and how to spot each one before it costs you.