entropy.h   [plain text]

/*
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//
// entropy - periodical to collect and seed entropy into /dev/random
//
#ifndef _H_ENTROPY
#define _H_ENTROPY

#include <security_utilities/machserver.h>
#include <security_utilities/timeflow.h>
#include <security_utilities/devrandom.h>

using namespace Security;
using MachPlusPlus::MachServer;


//
// A (one-off) timer object that manages system entropy
//
class EntropyManager : public MachServer::Timer, private DevRandomGenerator {
    // all the parameters you ever (should) want to change :-)
    static const int collectInterval = 600; // collect every 10 minutes
    static const int updateInterval = 3600 * 6; // update file every 6 hours
    static const int timingsToCollect = 40; // how many timings?

public:
	EntropyManager(MachPlusPlus::MachServer &srv, const char *entropyFile);
		
	void action();
    
	MachPlusPlus::MachServer	&server;		// to which we do setTimer()
    
private:
    string mEntropyFilePath;			// absolute path to entropy file
    Time::Absolute mNextUpdate;			// next time for entropy file update
    
    void collectEntropy();				// collect system timings and seed RNG
    void updateEntropyFile();			// update entropy file from RNG if it's time
    
    static const size_t entropyFileSize = 20;	// bytes (effectively one SHA-1 worth)
};

#endif //_H_ENTROPY