Unsigned is a fixed (but arbitrary) length unsigned integer arithmetic library for native PHP. It was created as a helper for the Random Extension Polyfill to remove hard dependency on the GMP. It may be useful for weird arithmetic with shifts and unsigned overflows that is used in RNGS, encryptors, hashes, etc. (But it won't be cryptographically secure! Time based attacks are quite possible because of some optimizations) Performance greatly depends on the PHP version, with PHP 8.0+ it performs quite nicely, only slightly slower than GMP.