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       1             : /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
       2             : /* This Source Code Form is subject to the terms of the Mozilla Public
       3             :  * License, v. 2.0. If a copy of the MPL was not distributed with this
       4             :  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
       5             : 
       6             : 
       7             : /*
       8             : ** prrng.h -- NSPR Random Number Generator
       9             : ** 
      10             : **
      11             : ** lth. 29-Oct-1999.
      12             : */
      13             : 
      14             : #ifndef prrng_h___ 
      15             : #define prrng_h___
      16             : 
      17             : #include "prtypes.h"
      18             : 
      19             : PR_BEGIN_EXTERN_C
      20             : 
      21             : /*
      22             : ** PR_GetRandomNoise() -- Get random noise from the host platform
      23             : **
      24             : ** Description:
      25             : ** PR_GetRandomNoise() provides, depending on platform, a random value.
      26             : ** The length of the random value is dependent on platform and the
      27             : ** platform's ability to provide a random value at that moment.
      28             : **
      29             : ** The intent of PR_GetRandomNoise() is to provide a "seed" value for a
      30             : ** another random number generator that may be suitable for
      31             : ** cryptographic operations. This implies that the random value
      32             : ** provided may not be, by itself, cryptographically secure. The value
      33             : ** generated by PR_GetRandomNoise() is at best, extremely difficult to
      34             : ** predict and is as non-deterministic as the underlying platfrom can
      35             : ** provide.
      36             : **
      37             : ** Inputs:
      38             : **   buf -- pointer to a caller supplied buffer to contain the
      39             : **          generated random number. buf must be at least as large as
      40             : **          is specified in the 'size' argument.
      41             : **
      42             : **   size -- the requested size of the generated random number
      43             : **
      44             : ** Outputs:
      45             : **   a random number provided in 'buf'.
      46             : **
      47             : ** Returns:
      48             : **   PRSize value equal to the size of the random number actually
      49             : **   generated, or zero. The generated size may be less than the size
      50             : **   requested. A return value of zero means that PR_GetRandomNoise() is
      51             : **   not implemented on this platform, or there is no available noise
      52             : **   available to be returned at the time of the call.
      53             : **
      54             : ** Restrictions:
      55             : **   Calls to PR_GetRandomNoise() may use a lot of CPU on some platforms.
      56             : **   Some platforms may block for up to a few seconds while they
      57             : **   accumulate some noise. Busy machines generate lots of noise, but
      58             : **   care is advised when using PR_GetRandomNoise() frequently in your
      59             : **   application.
      60             : **
      61             : ** History:
      62             : **   Parts of the model dependent implementation for PR_GetRandomNoise()
      63             : **   were taken in whole or part from code previously in Netscape's NSS
      64             : **   component.
      65             : **
      66             : */
      67           3 : NSPR_API(PRSize) PR_GetRandomNoise( 
      68             :     void    *buf,
      69             :     PRSize  size
      70             : );
      71             : 
      72             : PR_END_EXTERN_C
      73             : 
      74             : #endif /* prrng_h___ */
      75             : /* end prrng.h */