Intermediate Topic 23 of 51 Security & Cryptography
Message Authentication Codes
Keyed tags verifying message integrity.
How it works
A MAC (HMAC, Poly1305) uses a shared key to produce a tag proving message integrity and authenticity; verify with constant-time comparison.
Where it is used
API request signing, cookies.
Common pitfall
Encryption alone does not prevent tampering.
Where it fits in the course
Message Authentication Codes is topic 23 of 51 in Security & Cryptography, rated Intermediate. It follows Block Cipher Modes. The next topic is SQL Injection.
Practice and explore
- Open the interactive lesson, with a mini quiz.
- Take the Security & Cryptography quiz.
How to study this topic
- Read the explanation above and restate the definition in your own words.
- Open the interactive lesson and answer its mini quiz.
- Read the common pitfall, then write a short example that avoids it.
- Check your understanding in the Security & Cryptography quiz, and revisit the topic if you miss a question.
Frequently asked questions
What is Message Authentication Codes?
Keyed tags verifying message integrity. It belongs to Security & Cryptography and is an intermediate-level topic.
Where do people use Message Authentication Codes?
API request signing, cookies.
What is the most common mistake with Message Authentication Codes?
Encryption alone does not prevent tampering.
What should I learn before this topic?
Start with Block Cipher Modes, the topic just before it in Security & Cryptography.
How can I practice it?
Answer the mini quiz in the interactive lesson, then take the Security & Cryptography quiz.
Is Message Authentication Codes hard to learn?
It is an Intermediate topic. Be comfortable with the Beginner topics in this area first, then read the common pitfall carefully, since it is where most mistakes happen.
How long does it take to learn Message Authentication Codes?
Most learners can read the explanation and finish the interactive lesson in under an hour. Fluency comes from applying the idea, so plan a few short practice sessions with the quiz.
Which topics are related to Message Authentication Codes?
Block Cipher Modes, SQL Injection, Diffie-Hellman Key Exchange are closely connected. The full list is in the related topics section of this page.
What should I study after Message Authentication Codes?
Continue with SQL Injection, the next topic in Security & Cryptography.
Related topics
- Block Cipher Modes (Security & Cryptography)
- SQL Injection (Security & Cryptography)
- Diffie-Hellman Key Exchange (Security & Cryptography)
- Cross-Site Scripting (Security & Cryptography)
- Message Queues (Distributed Systems & Cloud)
- Authentication Flows (Web Development)