Encryption & Hashing

Q: Is the Encryption & Hashing quiz free?

Yes. The Encryption & Hashing quiz is completely free with no signup. Answer the questions, get instant scoring, and earn XP as you go.

Q: What level is the Encryption & Hashing quiz?

This is a Medium-level quiz. Each question includes the correct answer so you learn as you test yourself, whatever your starting point.

Q: How can I prepare for this quiz?

Review the linked courses and notes for the topic first, then take the quiz to check your understanding. You can retake it anytime to track improvement.

Question 1

What is the key difference between symmetric and asymmetric encryption?

Accepted Answer

Symmetric encryption (e.g., AES) uses one shared key — fast, but key distribution is a challenge. Asymmetric encryption (e.g., RSA) uses a key pair: the public key encrypts, only the matching private key decrypts.

Question 2

What are the supported key sizes for AES (Advanced Encryption Standard)?

Accepted Answer

AES supports three key sizes: 128-bit (10 rounds), 192-bit (12 rounds), and 256-bit (14 rounds). AES-256 is the strongest and is widely used for sensitive data protection.

Question 3

In RSA asymmetric encryption, what are the public and private keys used for?

Accepted Answer

The public key is shared openly and used to encrypt messages or verify digital signatures. The private key is kept secret and used to decrypt messages or create digital signatures.

Question 4

Hashing is a one-way operation — it is computationally infeasible to reverse a hash back to the original input.

Accepted Answer

True. Hash functions (SHA-256, bcrypt, etc.) are designed to be one-way. You can verify a value by hashing it and comparing, but you cannot mathematically reverse the hash to recover the original input.

Question 5

What is the output size of SHA-256?

Accepted Answer

SHA-256 always produces a 256-bit (32-byte) hash digest regardless of the input size. This fixed-length output is typically expressed as a 64-character hexadecimal string.

Question 6

Why is bcrypt preferred over SHA-256 for hashing user passwords?

Accepted Answer

bcrypt is a password-hashing function designed to be slow and computationally expensive. Its cost factor can be increased over time to stay ahead of faster hardware. It also automatically handles salting.

Question 7

What is the purpose of the TLS handshake?

Accepted Answer

The TLS handshake negotiates the protocol version, verifies the server's certificate (authentication), and uses asymmetric cryptography to securely exchange symmetric session keys for the rest of the communication.

Question 8

What is the role of a Certificate Authority (CA) in web security?

Accepted Answer

A CA (like Let's Encrypt, DigiCert) digitally signs SSL/TLS certificates. Browsers trust CAs by default; when they see a valid certificate signed by a trusted CA, they confirm the server is who it claims to be.

Question 9

What does end-to-end encryption (E2EE) guarantee?

Accepted Answer

With E2EE (used by WhatsApp, Signal), messages are encrypted on the sender's device and only decrypted on the recipient's device. Even the platform's own servers cannot read the content.

Question 10

How does salting prevent rainbow table attacks on password hashes?

Accepted Answer

Rainbow tables are precomputed hash-to-password mappings. Since each password gets a unique random salt before hashing, two users with the same password have different hashes, making rainbow tables useless.

Encryption & Hashing

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