True-ish random number generation.

(*
  Pseudo-random number generation enhanced with an external entropy source (webcam image).
  It does not meet the strictest criteria for true randomness, but it comes as close
  as we easily can without specialized hardware. Further more entropy image is
  not updated fast enough to truly be unpredictable within a 1 minute window,
  a better source could be found, and the camera may not be able to deal well with
  night-time, which means entropy may reduce.

  But on a longer timeframe this can not be predicted, nor replicated,
  even though short sequences within it can be individually solved for
  assuming enough data is collected.
*)

var entropyUpdateTimer:Double;
function TrueRandom(x,y: Int32): Int32;
var
  trueRnd: UInt64;
  rnd: TImage;
  r,t:single;
  data: string;
begin
  // grab random world data, in our case an image is the source of entropy
  // however this image only updates every 1 minute at the source
  // so that makes 1 minute sequences of this deterministic.
  // For optimal entropy find a live source with *a lot* of data.
  // weather patterns are likely a good source (if can be found online).
  if PerformanceTimer() > entropyUpdateTimer then
  begin
    HTTPClient.GetFile('https://kamera.atlas.vegvesen.no/api/images/0329003_1', 'rndgen.jpg');

    //65 seconds as image updates once every minute.
    entropyUpdateTimer := PerformanceTimer() + 1000*65;
  end;

  // load real world data as simi-undeterministic spice to pseudo random number generation
  rnd := TImage.Create('rndgen.jpg');
  data := HashData(EHashAlgo.SHA256, rnd.data, rnd.Width*rnd.Height*4);
  SetLength(data, 16); // we only care about the first 64 bits.
  rnd.Free();

  //a true-ish random number in the range 0..High(UInt64)
  trueRnd := StrToInt64('$'+data);

  //a true-ish random number in the incomplete range 0..1
  t := trueRnd / High(UInt64);

  r := x + t * 1/t * y * random();
  Result := Round(r);
end;


var
  myIds := [543,11,99,664,14];
begin
  for 0 to 1000 do
    Writeln TrueRandom(0,1000);
end;