blob: 22fdd4da72c83f9e8c189d6467c82d730f5c7f0f [file] [log] [blame]
// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "base/rand_util.h"
#include <windows.h>
#include <stddef.h>
#include <stdint.h>
// #define needed to link in RtlGenRandom(), a.k.a. SystemFunction036. See the
// "Community Additions" comment on MSDN here:
#define SystemFunction036 NTAPI SystemFunction036
#include <NTSecAPI.h>
#undef SystemFunction036
#include <algorithm>
#include <limits>
#include "base/logging.h"
namespace base {
// NOTE: This function must be cryptographically secure.
uint64_t RandUint64() {
uint64_t number;
RandBytes(&number, sizeof(number));
return number;
void RandBytes(void* output, size_t output_length) {
char* output_ptr = static_cast<char*>(output);
while (output_length > 0) {
const ULONG output_bytes_this_pass = static_cast<ULONG>(std::min(
output_length, static_cast<size_t>(std::numeric_limits<ULONG>::max())));
const bool success =
RtlGenRandom(output_ptr, output_bytes_this_pass) != FALSE;
output_length -= output_bytes_this_pass;
output_ptr += output_bytes_this_pass;
} // namespace base