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HWRand.Net

A small .Net Framework 4.8 library that allows you to directly call your CPUs RDRAND and RDSEED instructions, this is done by calling a C wrapper for x86-64 assembly with P/Invoke.

Features

  • No direct heap allocations (only static functions)
  • easy to use
  • Span support via System.Memory
  • easy compatibility check via build-in function that uses CPUID

How to Use

To check compatibility

if (HWRandom.HardwareRandomIsPresent())
{
    Console.WriteLine("CPU compatible!");
    Worker.Start();

    Environment.Exit(0);
}
else
{
    Console.WriteLine("RDRAND/RDSEED instruction NOT available on CPU!");
    Environment.Exit(-1);
}

To get random numbers form the DRNG pool (RDRAND)

// define values
UInt64 _64RandomBits = 0;
UInt32 _32RandomBits = 0;
UInt16 _16RandomBits = 0;
Byte _8RandomBits = 0;

// fill values
HWRandom.ReadRandom64(_64RandomBits);
HWRandom.ReadRandom32(_32RandomBits);
HWRandom.ReadRandom16(_16RandomBits);
HWRandom.ReadRandom8(_8RandomBits);

Console.WriteLine("rand on 64 bit register: " + _64RandomBits);
Console.WriteLine("rand on 32 bit register: " + _32RandomBits);
Console.WriteLine("rand on 16 bit register: " + _16RandomBits);
Console.WriteLine("rand on 16 bit register (only 8 are returned by native function): " + _8RandomBits);

To get random numbers form the ENRNG (RDSEED)

// define values
UInt64 _64RandomBits = 0;
UInt32 _32RandomBits = 0;
UInt16 _16RandomBits = 0;
Byte _8RandomBits = 0;

// fill values
HWRandom.ReadSeed64(_64RandomBits);
HWRandom.ReadSeed32(_32RandomBits);
HWRandom.ReadSeed16(_16RandomBits);
HWRandom.ReadSeed8(_8RandomBits);

Console.WriteLine("seed on 64 bit register: " + _64RandomBits);
Console.WriteLine("seed on 32 bit register: " + _32RandomBits);
Console.WriteLine("seed on 16 bit register: " + _16RandomBits);
Console.WriteLine("seed on 16 bit register (only 8 are returned by native function): " + _8RandomBits);

To fill a buffer

Byte[] bytes = new Byte[254];

// use RDRAND to fill buffer
HWRandom.NextBytes(bytes, 0, (UInt64)bytes.LongLength);

// use RDSEED to fill buffer
HWRandom.SeedNextBytes(bytes.AsSpan());

Intel® Digital Random Number Generator (DRNG) Software Implementation Guide