1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #include "base/rand_util.h" 6 7 #include <windows.h> 8 9 // #define needed to link in RtlGenRandom(), a.k.a. SystemFunction036. See the 10 // "Community Additions" comment on MSDN here: 11 // http://msdn.microsoft.com/en-us/library/windows/desktop/aa387694.aspx 12 #define SystemFunction036 NTAPI SystemFunction036 13 #include <NTSecAPI.h> 14 #undef SystemFunction036 15 16 #include <algorithm> 17 #include <limits> 18 19 #include "base/logging.h" 20 21 namespace base { 22 23 // NOTE: This function must be cryptographically secure. http://crbug.com/140076 24 uint64 RandUint64() { 25 uint64 number; 26 RandBytes(&number, sizeof(number)); 27 return number; 28 } 29 30 void RandBytes(void* output, size_t output_length) { 31 char* output_ptr = static_cast<char*>(output); 32 while (output_length > 0) { 33 const ULONG output_bytes_this_pass = static_cast<ULONG>(std::min( 34 output_length, static_cast<size_t>(std::numeric_limits<ULONG>::max()))); 35 const bool success = 36 RtlGenRandom(output_ptr, output_bytes_this_pass) != FALSE; 37 CHECK(success); 38 output_length -= output_bytes_this_pass; 39 output_ptr += output_bytes_this_pass; 40 } 41 } 42 43 } // namespace base 44
