Security-57031.1.35.tar.gz

[apple/security.git] / securityd / src / entropy.h

diff --git a/securityd/src/entropy.h b/securityd/src/entropy.h
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+/*
+ * Copyright (c) 2000-2004,2006 Apple Computer, Inc. All Rights Reserved.
+ * 
+ * @APPLE_LICENSE_HEADER_START@
+ * 
+ * This file contains Original Code and/or Modifications of Original Code
+ * as defined in and that are subject to the Apple Public Source License
+ * Version 2.0 (the 'License'). You may not use this file except in
+ * compliance with the License. Please obtain a copy of the License at
+ * http://www.opensource.apple.com/apsl/ and read it before using this
+ * file.
+ * 
+ * The Original Code and all software distributed under the License are
+ * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
+ * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
+ * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
+ * Please see the License for the specific language governing rights and
+ * limitations under the License.
+ * 
+ * @APPLE_LICENSE_HEADER_END@
+ */
+
+
+//
+// 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