2
* Copyright (c) 2009 Joshua Oreman <oremanj@rwcr.net>.
4
* This program is free software; you can redistribute it and/or
5
* modify it under the terms of the GNU General Public License as
6
* published by the Free Software Foundation; either version 2 of the
7
* License, or any later version.
9
* This program is distributed in the hope that it will be useful, but
10
* WITHOUT ANY WARRANTY; without even the implied warranty of
11
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12
* General Public License for more details.
14
* You should have received a copy of the GNU General Public License
15
* along with this program; if not, write to the Free Software
16
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
19
FILE_LICENCE ( GPL2_OR_LATER );
23
* Cryptographically strong random number generator
25
* Currently the cryptographic part is not implemented, and this just
29
#include <ipxe/crypto.h>
33
* Get cryptographically strong random bytes
35
* @v buf Buffer in which to store random bytes
36
* @v len Number of random bytes to generate
38
* @b WARNING: This function is currently underimplemented, and does
39
* not give numbers any stronger than random()!
41
void get_random_bytes ( void *buf, size_t len )
46
* Somewhat arbitrarily, choose the 0x00FF0000-masked byte
47
* returned by random() as having good entropy. PRNGs often
48
* don't provide good entropy in lower bits, and the top byte
49
* might show a pattern because of sign issues.
53
*bufp++ = ( random() >> 16 ) & 0xFF;