pjs/nsprpub/pr/include/prrng.h

/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/*
 * The contents of this file are subject to the Netscape Public License
 * Version 1.1 (the "NPL"); you may not use this file except in
 * compliance with the NPL.  You may obtain a copy of the NPL at
 * http://www.mozilla.org/NPL/
 * 
 * Software distributed under the NPL is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the NPL
 * for the specific language governing rights and limitations under the
 * NPL.
 * 
 * The Initial Developer of this code under the NPL is Netscape
 * Communications Corporation.  Portions created by Netscape are
 * Copyright (C) 1999 Netscape Communications Corporation.  All Rights
 * Reserved.
 */

/*
** Delete this section of the header after (if) agreement is reached to
** provide the service suggested here. Move some parts of it, if
** appropriate to platform specific implementation files.
**
** Proposal: Nothing in this header file should be construed as a
** commitment on the part of the NSPR team, Netsacpe/AOL/Sun Alliance
** et.al. to provide the API or function suggested in this header file.
** This is a proposal, a draft, yadda. ... So, don't count on it.
** lth. 29-Oct-1999
**
** --------------------------------------------------------------------
**
** Requirements, Discussion:
**
** Goal: foreach platform, find at least 160 bits of "good noise", that
** is: from the platform itself, not extrapolated, stired, hashed,
** xor'd, whatever, from a little available noise.
**
**
** Required on the following platforms:
**   MAC, Win9x, WinNT, Solaris, Linux (k: 2.2.x).
** Best effort on: 
**   AIX, HP-UX.
** Not required on: 
**   Tru65 Unix (Compaq)
**
** Notes: 
** 
** I presume it is legal to put this function on Mozilla.org,
** that it is not regulated as "cryptographic 'munitions'". 
**
** Cartman says they need it 15-Jan-2000.
**
** --------------------------------------------------------------------
*/

/*
** prrng.h -- NSPR Random Number Generator
** 
** 
** 
** 
**
** lth. 29-Oct-1999.
*/

#ifndef prrng_h___ 
#define prrng_h___

#include "prtypes.h"

PR_BEGIN_EXTERN_C

/*
** PR_GetRandomNoise() -- Get random noise from the host platform
**
** Description:
** PR_GetRandomNoise() provides, depending on platform, a random value.
** The length of the random value is dependent on platform and the
** platform's ability to provide a random value at that moment.
**
** The intent of PR_GetRandomNoise() is to provide a "seed" value for a
** another random number generator that may be suitable for
** cryptographic operations. This implies that the random value
** provided may not be, by itself, cryptographically secure. The value
** generated by PR_GetRandomNoise() is at best, extremely difficult to
** predict and is as non-deterministic as the underlying platfrom can
** provide.
**
** Inputs:
**   buf -- pointer to a caller supplied buffer to contain the
**          generated random number. buf must be at least as large as
**          is specified in the 'size' argument.
**
**   size -- the requested size of the generated random number
**
** Outputs:
**   a random number provided in 'buf'.
**
** Returns:
**   PRSize value equal to the size of the random number actually
**   generated, or zero. The generated size may be less than the size
**   requested. A return value of zero means that PR_GetRandomNoise() is
**   not implemented on this platform, or there is no available noise
**   available to be returned at the time of the call.
**
** Restrictions:
**   Calls to PR_GetRandomNoise() may use a lot of CPU on some platforms.
**   Some platforms may block for up to a few seconds while they
**   accumulate some noise. Busy machines generate lots of noise, but
**   care is advised when using PR_GetRandomNoise() frequently in your
**   application.
**
** History:
**   Parts of the model dependent implementation for PR_GetRandomNoise()
**   were taken in whole or part from code previously in Netscape's NSS
**   component. There is no Goddamned Goverenment Munitions is this
**   code. Clinton: FOAD.
**
*/
NSPR_API(PRSize) PR_GetRandomNoise( 
    void    *buf,
    PRSize  size
);

PR_END_EXTERN_C

#endif /* prrng_h___ */
/* end prrng.h */