michael@0: /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: 
michael@0: /*
michael@0: ** prrng.h -- NSPR Random Number Generator
michael@0: ** 
michael@0: **
michael@0: ** lth. 29-Oct-1999.
michael@0: */
michael@0: 
michael@0: #ifndef prrng_h___ 
michael@0: #define prrng_h___
michael@0: 
michael@0: #include "prtypes.h"
michael@0: 
michael@0: PR_BEGIN_EXTERN_C
michael@0: 
michael@0: /*
michael@0: ** PR_GetRandomNoise() -- Get random noise from the host platform
michael@0: **
michael@0: ** Description:
michael@0: ** PR_GetRandomNoise() provides, depending on platform, a random value.
michael@0: ** The length of the random value is dependent on platform and the
michael@0: ** platform's ability to provide a random value at that moment.
michael@0: **
michael@0: ** The intent of PR_GetRandomNoise() is to provide a "seed" value for a
michael@0: ** another random number generator that may be suitable for
michael@0: ** cryptographic operations. This implies that the random value
michael@0: ** provided may not be, by itself, cryptographically secure. The value
michael@0: ** generated by PR_GetRandomNoise() is at best, extremely difficult to
michael@0: ** predict and is as non-deterministic as the underlying platfrom can
michael@0: ** provide.
michael@0: **
michael@0: ** Inputs:
michael@0: **   buf -- pointer to a caller supplied buffer to contain the
michael@0: **          generated random number. buf must be at least as large as
michael@0: **          is specified in the 'size' argument.
michael@0: **
michael@0: **   size -- the requested size of the generated random number
michael@0: **
michael@0: ** Outputs:
michael@0: **   a random number provided in 'buf'.
michael@0: **
michael@0: ** Returns:
michael@0: **   PRSize value equal to the size of the random number actually
michael@0: **   generated, or zero. The generated size may be less than the size
michael@0: **   requested. A return value of zero means that PR_GetRandomNoise() is
michael@0: **   not implemented on this platform, or there is no available noise
michael@0: **   available to be returned at the time of the call.
michael@0: **
michael@0: ** Restrictions:
michael@0: **   Calls to PR_GetRandomNoise() may use a lot of CPU on some platforms.
michael@0: **   Some platforms may block for up to a few seconds while they
michael@0: **   accumulate some noise. Busy machines generate lots of noise, but
michael@0: **   care is advised when using PR_GetRandomNoise() frequently in your
michael@0: **   application.
michael@0: **
michael@0: ** History:
michael@0: **   Parts of the model dependent implementation for PR_GetRandomNoise()
michael@0: **   were taken in whole or part from code previously in Netscape's NSS
michael@0: **   component.
michael@0: **
michael@0: */
michael@0: NSPR_API(PRSize) PR_GetRandomNoise( 
michael@0:     void    *buf,
michael@0:     PRSize  size
michael@0: );
michael@0: 
michael@0: PR_END_EXTERN_C
michael@0: 
michael@0: #endif /* prrng_h___ */
michael@0: /* end prrng.h */