5. Examples of hybrid random generators

The need for good-quality randomness is such that most operating systems today offer reserves of random numbers produced by HRNGs. This is the case, for example, with the /dev/random pseudo-file in Unix systems. Often these generators are CSPRNGs whose initial state is given by information from system peripherals (hard disk access time, network controller state, etc.), the processor (number of cache faults, state of branch predictors, etc.). The aim is to offer a high level of quality with CSPRNG and a non-reproducible character due to the use of physical entropy sources.

However, these devices are often complex and can be subject to attack if not implemented with sufficient care. This was the case with Windows 2000, for example