Similar to the hash function, Hash-based MACs (HMACs) produce a fixed-length output and take an arbitrarily long message as the input.
In this scheme, the sender signs a message using the MAC and the receiver verifies it using the shared key.
Verifying Data Integrity in Blockchain (Part 2)
The key is hashed with the message using either of the two methods known as secret prefix or the secret suffix.
With the secret prefix method, the key is concatenated with the message; that is, the key comes first and the message comes afterwards, whereas with the secret suffix method, the key comes after the message. equations: Secret prefix: M = MACk(x) = h(k||x) Secret suffix: M=MACk(x) = h(x||k) There are pros and cons to both methods.
There are HMAC constructions schemes that use various techniques, such as ipad and opad (inner padding and outer padding) that have been proposed by cryptographic researchers.
These are considered secure with some assumptions: Operation of a MAC function There are various powerful applications of hash functions used in peer-to-peer networks and blockchain technology.
Some noticeable examples, such as Merkle trees, Patricia trees, and Distributed Hash Table (DHT), are discussed in the following subsections.
Why This Matters for Blockchain Technology
Understanding Hash-based MACs is not just an academic exercise — it has real-world implications for how blockchain systems are designed, deployed, and secured. Whether you are a developer building decentralized applications, a business leader evaluating blockchain adoption, or a curious learner exploring the technology, this knowledge provides a critical foundation.
Key Points to Remember
- Hash-based MACs Similar to the hash function, Hash-based MACs (HMACs) produce a fixed-length output and take an arbitrarily long message as the input.
- In this scheme, the sender signs a message using the MAC and the receiver verifies it using the shared key.
- The key is hashed with the message using either of the two methods known as secret prefix or the secret suffix.
- There are HMAC constructions schemes that use various techniques, such as ipad and opad (inner padding and outer padding) that have been proposed by cryptographic researchers.
Conclusion
Hash-based MACs represents one of the many innovative layers that make blockchain technology so powerful and transformative. As distributed systems continue to evolve, a solid understanding of these core concepts becomes increasingly valuable — not just for developers, but for anyone building, investing in, or working alongside blockchain-powered systems.
Whether you are just starting your blockchain journey or deepening existing expertise, mastering these fundamentals gives you the tools to think clearly about decentralized systems and make smarter decisions in this rapidly evolving space.