Summary
In this chapter, we learned about encrypting data with a symmetric cipher, starting with AES. After learning about how to use AES, including how to choose the size of the key, how to select a mode of operation (especially CBC and GCM), and how to generate an IV, we saw code samples for encrypting and decrypting data and streams with AES using Node.js. We then learned about ChaCha20-Poly1305, another symmetric stream cipher that's similar to AES-GCM.
Next, we explained how to derive encryption keys from a passphrase, stretching lower-entropy strings into safer keys for usage with symmetric ciphers. We saw examples of doing that with Argon2.
Finally, we learned how keys can be wrapped (encrypted), and why doing so can help solve real-world problems when applications use keys derived from passphrases to encrypt and decrypt users' data.
The next chapter will be the first one that covers the other kind of ciphers – asymmetric ones. We'll learn how...
