prrng.h (2458B)
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 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 */