function BufToHex(const Buf; const Size: Cardinal): string;
const
  // maps nibbles to hex digits
  cHexDigits: array[$0..$F] of Char = (
    '0', '1', '2', '3', '4', '5', '6', '7',
    '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'
  );
var
  I: Cardinal;  // loops thru output string
  PB: ^Byte;    // addresses each byte in buffer
begin
  PB := @Buf;
//  Result := '';
  SetLength(Result, 2 * Size);
  I := 1;
  while I <= 2 * Size do
  begin
    Result[I] := cHexDigits[PB^ shr 4];
    Result[I + 1] := cHexDigits[PB^ and $0F];
    Inc(PB);
    Inc(I, 2);
  end;
end;
//delphi/2250