// Copyright 2005-2020 The Mumble Developers. All rights reserved.
// Use of this source code is governed by a BSD-style license
// that can be found in the LICENSE file at the root of the
// Mumble source tree or at <https://www.mumble.info/LICENSE>.

#ifndef MUMBLE_CRYPTOGRAPHICRANDOM_H_
#define MUMBLE_CRYPTOGRAPHICRANDOM_H_

#include <stdint.h>

/// CryptographicRandom provides useful utilities for acquiring
/// pseudo-random data for use in cryptography.
class CryptographicRandom {
	public:
		/// Fill the buffer at |buf| with |numBytes| bytes of pseudo-random data.
		/// The value of |numBytes| must be >= 0. Otherwise, program execution is aborted.
		///
		/// This function is equivalent to the arc4random_buf() function from OpenBSD.
		///
		/// This function should not ever fail. It is considered a catastrophic failure if
		/// it does. The program is aborted if the function fails, because it is generally
		/// impossible to recover from such a scenario.
		static void fillBuffer(void *buf, int numBytes);

		/// Return a pseudo-random number in the range of 0 to (2**32)-1.
		///
		/// This function is equivalent to the arc4random() function from OpenBSD.
		///
		/// This function should not ever fail. It is considered a catastrophic failure if
		/// it does. The program is aborted if the function fails, because it is generally
		/// impossible to recover from such a scenario.
		static uint32_t uint32();

		/// Calculate a uniformly distributed random number less than |upperBound|
		/// avoiding "modulo bias".
		///
		/// This function is equivalent to the arc4random_uniform() function from OpenBSD.
		///
		/// This function should not ever fail. It is considered a catastrophic failure if
		/// it does. The program is aborted if the function fails, because it is generally
		/// impossible to recover from such a scenario.
		static uint32_t uniform(uint32_t upperBound);
};

#endif