XXH3 hash

 

About XXH3 hash

XXH3 is the latest generation of the xxHash family of non-cryptographic hash functions, designed by Yann Collet. It introduces improvements over its predecessors, XXH32 and XXH64, aiming for even higher speed and better distribution of hash values. XXH3 is available in several variants, including XXH3-64bits and XXH3-128bits, which indicate the size of the hash output they produce.

Characteristics of XXH3

  1. Output Sizes:

    • XXH3 is available in multiple output sizes, primarily XXH3-64bits (producing a 64-bit hash) and XXH3-128bits (producing a 128-bit hash).

  2. Initialization Value:

    • Like other xxHash variants, XXH3 uses an initial seed value (seed) to start the hash computation. This seed can be any arbitrary value chosen by the user.

  3. Hash Calculation:

    • XXH3 processes the input data in blocks, typically of 16 bytes (128 bits) at a time.
    • It employs a mix of bitwise operations, rotations, and additions with prime constants to process each block of data.
    • The hash state is updated iteratively for each processed block until all data is processed.

  4. Properties:

    • XXH3 is designed to be extremely fast and efficient, often outperforming other hash functions in terms of speed.
    • It maintains good dispersion properties, ensuring that small changes in input data result in significantly different hash values (avalanche effect).
    • XXH3 is not designed for cryptographic purposes due to its predictable nature and vulnerability to collision attacks.

Usage

  • Applications: XXH3 is suitable for applications requiring fast computation of hash values with larger output sizes (64-bit or 128-bit). It is commonly used in hash tables, checksums, data deduplication, and other non-cryptographic hash-based operations.

  • Implementation: Implementing XXH3 is straightforward due to its well-defined algorithm and efficient use of computational resources.

Example Calculation

Given a sequence of bytes data and an initial seed seed, the XXH3 hash XXH3(data, seed) is calculated as follows:

  • Initialize the hash state with the seed value.
  • Process each block of data (typically 16 bytes) using specific mixing operations.
  • Finalize the hash value to ensure good dispersion and avalanche effect.
  • The final XXH3 hash value, depending on the variant (64-bit or 128-bit), is returned after processing all data blocks.

Security Considerations

  • XXH3, like other xxHash variants, is not suitable for cryptographic purposes due to its vulnerability to collision attacks and its predictable nature.
  • It should only be used in scenarios where speed and good distribution of hash values are more critical than cryptographic security.

Summary

XXH3 is a highly efficient non-cryptographic hash function designed for rapid computation of hash values with larger output sizes (64-bit or 128-bit). It builds upon the success of its predecessors, XXH32 and XXH64, offering improved performance and reliability for various applications requiring fast hash computation. However, it should not be used for cryptographic applications where strong security guarantees are needed.