php_mt_seed finds possible seeds given the very first PHP mt_rand() output after possible seeding with mt_srand(). With advanced invocation modes, php_mt_seed is also able to match multiple, non-first, and/or inexact mt_rand() outputs to possible seed values. php_mt_seed is written in C with optional SIMD intrinsics (SSE4.1/AVX, XOP, AVX2, MIC) and OpenMP. On a modern quad-core CPU, it is able to search the full 32-bit seed space in one minute (or in just seven seconds on Xeon Phi).
