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/gecko_api/include/prrng.h

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  1/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
  2/* ***** BEGIN LICENSE BLOCK *****
  3 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
  4 *
  5 * The contents of this file are subject to the Mozilla Public License Version
  6 * 1.1 (the "License"); you may not use this file except in compliance with
  7 * the License. You may obtain a copy of the License at
  8 * http://www.mozilla.org/MPL/
  9 *
 10 * Software distributed under the License is distributed on an "AS IS" basis,
 11 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 12 * for the specific language governing rights and limitations under the
 13 * License.
 14 *
 15 * The Original Code is the Netscape Portable Runtime (NSPR).
 16 *
 17 * The Initial Developer of the Original Code is
 18 * Netscape Communications Corporation.
 19 * Portions created by the Initial Developer are Copyright (C) 1999-2000
 20 * the Initial Developer. All Rights Reserved.
 21 *
 22 * Contributor(s):
 23 *
 24 * Alternatively, the contents of this file may be used under the terms of
 25 * either the GNU General Public License Version 2 or later (the "GPL"), or
 26 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 27 * in which case the provisions of the GPL or the LGPL are applicable instead
 28 * of those above. If you wish to allow use of your version of this file only
 29 * under the terms of either the GPL or the LGPL, and not to allow others to
 30 * use your version of this file under the terms of the MPL, indicate your
 31 * decision by deleting the provisions above and replace them with the notice
 32 * and other provisions required by the GPL or the LGPL. If you do not delete
 33 * the provisions above, a recipient may use your version of this file under
 34 * the terms of any one of the MPL, the GPL or the LGPL.
 35 *
 36 * ***** END LICENSE BLOCK ***** */
 37
 38
 39/*
 40** prrng.h -- NSPR Random Number Generator
 41** 
 42**
 43** lth. 29-Oct-1999.
 44*/
 45
 46#ifndef prrng_h___ 
 47#define prrng_h___
 48
 49#include "prtypes.h"
 50
 51PR_BEGIN_EXTERN_C
 52
 53/*
 54** PR_GetRandomNoise() -- Get random noise from the host platform
 55**
 56** Description:
 57** PR_GetRandomNoise() provides, depending on platform, a random value.
 58** The length of the random value is dependent on platform and the
 59** platform's ability to provide a random value at that moment.
 60**
 61** The intent of PR_GetRandomNoise() is to provide a "seed" value for a
 62** another random number generator that may be suitable for
 63** cryptographic operations. This implies that the random value
 64** provided may not be, by itself, cryptographically secure. The value
 65** generated by PR_GetRandomNoise() is at best, extremely difficult to
 66** predict and is as non-deterministic as the underlying platfrom can
 67** provide.
 68**
 69** Inputs:
 70**   buf -- pointer to a caller supplied buffer to contain the
 71**          generated random number. buf must be at least as large as
 72**          is specified in the 'size' argument.
 73**
 74**   size -- the requested size of the generated random number
 75**
 76** Outputs:
 77**   a random number provided in 'buf'.
 78**
 79** Returns:
 80**   PRSize value equal to the size of the random number actually
 81**   generated, or zero. The generated size may be less than the size
 82**   requested. A return value of zero means that PR_GetRandomNoise() is
 83**   not implemented on this platform, or there is no available noise
 84**   available to be returned at the time of the call.
 85**
 86** Restrictions:
 87**   Calls to PR_GetRandomNoise() may use a lot of CPU on some platforms.
 88**   Some platforms may block for up to a few seconds while they
 89**   accumulate some noise. Busy machines generate lots of noise, but
 90**   care is advised when using PR_GetRandomNoise() frequently in your
 91**   application.
 92**
 93** History:
 94**   Parts of the model dependent implementation for PR_GetRandomNoise()
 95**   were taken in whole or part from code previously in Netscape's NSS
 96**   component.
 97**
 98*/
 99NSPR_API(PRSize) PR_GetRandomNoise( 
100    void    *buf,
101    PRSize  size
102);
103
104PR_END_EXTERN_C
105
106#endif /* prrng_h___ */
107/* end prrng.h */