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