Introduction to Data Encoding, Hashing, and Cryptography

In system design, data is rarely used in its raw form. As data moves between applications, services, databases, and networks, it must be transformed, validated, and protected. Data encoding, hashing, and cryptography are three fundamental techniques that enable system to handle data efficiently, reliably, and securely.

Although these concepts are often mentioned together, they serve very different purposes. Encoding is used to convert data into a different format so it can be properly stored or transmitted. It does not provide security and is fully reversible. Hashing transforms data into a fixed-size value that cannot be reversed, making it ideal for integrity checks and secure comparisons. Cryptography, specifically encryption, is designed to protect data from unauthorized access while allowing authorized parties to recover the original data using keys.

Understanding the distinction between these techniques is critical for system designers. Misusing encoding where encryption is required, or using weak hashing mechanisms for sensitive data, can lead to serious security vulnerabilities.

From a system design perspective, these techniques appear in many places:

• APIs encoding data for network transmission
• Database hashing passwords and indexing data
• Distributed systems using hashes for sharding and load balancing
• Secure communication relying on encryption and key exchange