/// <summary>
/// Creates an array of bytes with a cryptographically strong random sequence of values.
/// </summary>
/// <param name="count">The number of bytes of random values to create.</param>
/// <returns>
/// An array populated with cryptographically strong random values.
/// </returns>
/// <exception cref="ArgumentOutOfRangeException">
/// <paramref name="count" /> is less than zero.
/// </exception>
public static byte[] GetBytes(int count)
{
if (count < 0)
{
throw new ArgumentOutOfRangeException(nameof(count), SR.ArgumentOutOfRange_NeedNonNegNum);
}
byte[] ret = new byte[count];
RandomNumberGeneratorImplementation.FillSpan(ret);
return(ret);
}
public static int GetInt32(int fromInclusive, int toExclusive)
{
if (fromInclusive >= toExclusive)
{
throw new ArgumentException(SR.Argument_InvalidRandomRange);
}
// The total possible range is [0, 4,294,967,295).
// Subtract one to account for zero being an actual possibility.
uint range = (uint)toExclusive - (uint)fromInclusive - 1;
// If there is only one possible choice, nothing random will actually happen, so return
// the only possibility.
if (range == 0)
{
return(fromInclusive);
}
// Create a mask for the bits that we care about for the range. The other bits will be
// masked away.
uint mask = range;
mask |= mask >> 1;
mask |= mask >> 2;
mask |= mask >> 4;
mask |= mask >> 8;
mask |= mask >> 16;
uint oneUint = 0;
Span <byte> oneUintBytes = MemoryMarshal.AsBytes(new Span <uint>(ref oneUint));
uint result;
do
{
RandomNumberGeneratorImplementation.FillSpan(oneUintBytes);
result = mask & oneUint;
}while (result > range);
return((int)result + fromInclusive);
}
public static void Fill(Span <byte> data)
{
RandomNumberGeneratorImplementation.FillSpan(data);
}
