What is XEVAN?

XEVAN is a proof-of-work hashing algorithm that extends the X17 algorithm family by modifying it to operate with 128-bit hash lengths in its intermediate steps, effectively doubling the internal state compared to the standard 64-bit processing of X-series algorithms. The algorithm chains together seventeen different cryptographic hash functions — the same set used in X17, including BLAKE, Blue Midnight Wish, Grøstl, JH, Keccak, Skein, Luffa, CubeHash, SHAvite-3, SIMD, ECHO, Hamsi, Fugue, Shabal, Whirlpool, SHA-512, and Haval — but processes them with an expanded 128-bit hash size. The final output is then truncated to produce the standard 256-bit hash result.

The 128-bit internal processing of XEVAN substantially increases the computational and memory requirements compared to standard X-series algorithms, providing enhanced security through a larger internal state that is more resistant to certain classes of cryptographic attacks. This expanded processing makes XEVAN significantly more demanding on hardware, which initially served as an effective barrier against ASIC development. The algorithm offers strong collision resistance and benefits from the diversity of its seventeen component hash functions, ensuring that a weakness in any single function does not compromise the overall security. The higher computational intensity also means higher energy consumption per hash compared to simpler algorithms, which is a trade-off for the enhanced security properties.

XEVAN was introduced as the mining algorithm for Bitsend (BSD), a cryptocurrency project that launched in 2014 and later adopted XEVAN to differentiate itself from the growing number of X11 and X13-based coins. The algorithm was also adopted by other smaller cryptocurrency projects seeking to provide GPU-friendly mining with enhanced ASIC resistance. While XEVAN never achieved widespread adoption compared to more mainstream algorithms, it represents an interesting approach to extending the X-series concept beyond simply adding more hash functions, by instead modifying the fundamental processing width. The algorithm remains in use by a small number of active cryptocurrency projects within the broader altcoin ecosystem.