XXH

XXH is a family of cryptographic hash functions designed to provide high performance while maintaining strong security properties. Developed by Thomas Pornin, XXH is part of the xxHash suite, which includes several variants optimized for different use cases. The primary goal of XXH is to offer faster computation than traditional hash functions like MD5 or SHA-1 while still delivering a low collision rate, making it suitable for applications requiring efficient hashing, such as databases, caching systems, and checksum verification.

The original XXH algorithm, introduced in 2012, was designed to be extremely fast, often outperforming other non-cryptographic hash functions like MurmurHash or CityHash in benchmark tests. It achieves this speed through a combination of simple arithmetic operations, bitwise manipulations, and a carefully optimized mixing process. XXH is non-cryptographic, meaning it is not intended for security-sensitive applications like password storage or digital signatures, but rather for general-purpose hashing where speed is prioritized over cryptographic resistance.

XXH comes in several variants, including XXH3, which was released in 2017 as a significant redesign aimed at improving both speed and security. XXH3 incorporates additional features such as better resistance to certain types of collisions and improved memory efficiency. It also supports customizable seed values, allowing for deterministic yet varied hash outputs when needed.

The algorithm is widely used in software projects due to its simplicity, efficiency, and permissive licensing (BSD-style). It is integrated into popular libraries and frameworks, including the xxHash library for C, which serves as the reference implementation. While XXH is not considered cryptographically secure, its performance and reliability make it a popular choice for non-security-critical applications where fast hashing is essential.