OSX/libsecurity_utilities/lib/devrandom.h

   1 /*
   2  * Copyright (c) 2000-2004,2011,2014 Apple 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,
  17  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  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 // devrandom - RNG operations based on /dev/random
  27 //
  28 #ifndef _H_DEVRANDOM
  29 #define _H_DEVRANDOM
  30
  31 #include <security_utilities/utilities.h>
  32 #include <security_utilities/unix++.h>
  33 #include <security_utilities/globalizer.h>
  34
  35
  36 namespace Security {
  37
  38
  39 //
  40 // This RNG doesn't use /dev/random for reading, it uses CommonCrypto
  41 // (same as SecRandom does).  It is not repeatable.
  42 //
  43 // AddEntropy() contributes random entropy to a global pool (only).
  44 //
  45 class DevRandomGenerator {
  46         struct Writable : public UnixPlusPlus::FileDesc {
  47                 Writable() { open("/dev/random", O_RDWR); }
  48         };
  49
  50 public:
  51     DevRandomGenerator(bool writable = false);
  52
  53     void random(void *data, size_t length);
  54     void addEntropy(const void *data, size_t length);
  55
  56 private:
  57         static ModuleNexus<Writable> mWriter;
  58 };
  59
  60
  61 };      // end namespace Security
  62
  63
  64 #endif //_H_DEVRANDOM