1/*
2 * Copyright (c) 2000-2004,2006 Apple Computer, Inc. All Rights Reserved.
3 *
4 * @APPLE_LICENSE_HEADER_START@
5 *
6 * This file contains Original Code and/or Modifications of Original Code
7 * as defined in and that are subject to the Apple Public Source License
8 * Version 2.0 (the 'License'). You may not use this file except in
9 * compliance with the License. Please obtain a copy of the License at
10 * http://www.opensource.apple.com/apsl/ and read it before using this
11 * file.
12 *
13 * The Original Code and all software distributed under the License are
14 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
15 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
16 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
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18 * Please see the License for the specific language governing rights and
19 * limitations under the License.
20 *
21 * @APPLE_LICENSE_HEADER_END@
22 */
23
24
25//
26// entropy - periodical to collect and seed entropy into /dev/random
27//
28#ifndef _H_ENTROPY
29#define _H_ENTROPY
30
31#include <security_utilities/machserver.h>
32#include <security_utilities/timeflow.h>
33#include <security_utilities/devrandom.h>
34
35using namespace Security;
36using MachPlusPlus::MachServer;
37
38
39//
40// A (one-off) timer object that manages system entropy
41//
42class EntropyManager : public MachServer::Timer, private DevRandomGenerator {
43    // all the parameters you ever (should) want to change :-)
44    static const int collectInterval = 600; // collect every 10 minutes
45    static const int updateInterval = 3600 * 6; // update file every 6 hours
46    static const int timingsToCollect = 40; // how many timings?
47
48public:
49	EntropyManager(MachPlusPlus::MachServer &srv, const char *entropyFile);
50
51	void action();
52
53	MachPlusPlus::MachServer	&server;		// to which we do setTimer()
54
55private:
56    string mEntropyFilePath;			// absolute path to entropy file
57    Time::Absolute mNextUpdate;			// next time for entropy file update
58
59    void collectEntropy();				// collect system timings and seed RNG
60    void updateEntropyFile();			// update entropy file from RNG if it's time
61
62    static const size_t entropyFileSize = 20;	// bytes (effectively one SHA-1 worth)
63};
64
65#endif //_H_ENTROPY
66