Go Secret Scanner Boosts Shannon Entropy Speed 41% With Precomputed Lookup Table

Developer Khaled Hani improved the entropy analysis stage of Crenox, an open-source Git secret scanner, achieving a 41.4% increase in throughput with zero additional heap allocations. The scanner uses a three-tier pipeline where Shannon entropy analysis identifies high-randomness strings like tokens and credentials as potential secrets. The key insight was algebraically reformulating the Shannon entropy equation so that the costly per-byte floating-point operations could be replaced by a small precomputed lookup table indexed by byte frequency counts. Because byte frequencies in short inputs are bounded integers, values up to 512 bytes can be resolved with a fast table lookup instead of repeated division and logarithm calls. The optimization required no unsafe code, assembly, or CGo — only a mathematical rearrangement of the standard entropy formula.