Quiz — Encryption
10-question quiz on AES, RSA, PKI, and digital signatures
Encryption Types — Module Quiz
You treated AES as one shared secret both ways: fast bulk confidentiality, AES-128/256 as a standard — not a notebook XOR — with a key-distribution problem and IVs/nonces that must never be reused with the same key. openssl enc -aes-256-cbc -salt -pbkdf2 on a toy file in $HOME/cyberlium-lab was a teaching decrypt; real apps prefer AES-GCM (AEAD) so tampering is detected. Lab passphrases were never real passwords. Homebrew ciphers stayed dead. RSA was a pair: public shareable, private secret, 2048-bit toys you deleted. Slow on purpose — wrap AES keys and sign, do not encrypt a video. Hybrid TLS preview: asymmetric (or key-agreement) then symmetric bulk. PKI bound a name to a public key with a chain to a trust anchor; genrsa was not identity; self-signed toys were not banks. Signatures hashed then signed with private, verified with public: authenticity + integrity, not confidentiality; no forging. Ten APPLY items. No factoring moduli. No site attacks. No rogue roots. Next — How TLS Handshake Works — still on literacy, still not decrypting other people’s HTTPS. Proceed continues to TLS & HTTPS.
APPLY: A teammate wants to protect a large backup they own. They propose a homemade XOR “cipher,” reuse their email password as the openssl passphrase, and paste that passphrase in the same chat as the .enc file. What is AES, and what belongs in $HOME/cyberlium-lab?
APPLY: True or False: AES-256-CBC via openssl enc already guarantees integrity, so you should reuse a zero IV for every file “for reproducibility,” and flipping bits on a classmate’s disk is a defensive GCM lab.
APPLY: You generated toy-rsa-private.pem with openssl genrsa 2048. A friend wants to RSA-encrypt a course video with it, publish the private pem so “encryption to me works,” and factor a payment site’s modulus. Correct use of the pair?
APPLY: A browser shows a padlock on https://evil-bank.example with a valid chain. Your roommate generated a self-signed CN=your-real-bank cert and wants it installed as a root so “PKI makes sense.” What did PKI bind, and what do you refuse?
APPLY: Select the pair that matches this module’s crypto-and-ethics bar. (Select 2)
APPLY: TLS (previewed here, taught next) often uses asymmetric crypto or key-agreement and then AES-class bulk. A classmate says that means you should RSA-decrypt a random HTTPS site “to practice the handshake” and skip certificates. What is the hybrid idea, and what stays closed?
APPLY: True or False: A public key should be kept as secret as a password, and openssl genrsa on your laptop proves browsers must treat you as paypal.com until you factor someone else’s modulus to “verify.”
APPLY: openssl dgst -sha256 -sign produced toy-sig-notes.sig for a readable notes.txt you wrote. Verify is OK; after you change one character, verify fails. A friend says you should forge a new signature with a vendor’s public key so the OS updater accepts their patch. What happened, and what is forbidden?
APPLY: You are explaining a certificate chain to a junior: leaf for api.example, intermediate CA, root already in the OS store, dates valid, name matches the host they typed. Which operational reading is correct?
APPLY: After this quiz the proceed button is Continue to TLS & HTTPS (nextLessonTitle: How TLS Handshake Works). What still needs a human, what did Module 2 lock in, and which gray zone stays closed?