mirror of
https://github.com/ipxe/ipxe
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56 lines
1.6 KiB
C
56 lines
1.6 KiB
C
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/*
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* Copyright (c) 2009 Joshua Oreman <oremanj@rwcr.net>.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of the
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* License, or any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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FILE_LICENCE ( GPL2_OR_LATER );
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/** @file
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*
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* Cryptographically strong random number generator
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*
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* Currently the cryptographic part is not implemented, and this just
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* uses random().
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*/
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#include <gpxe/crypto.h>
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#include <stdlib.h>
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/**
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* Get cryptographically strong random bytes
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*
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* @v buf Buffer in which to store random bytes
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* @v len Number of random bytes to generate
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*
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* @b WARNING: This function is currently underimplemented, and does
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* not give numbers any stronger than random()!
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*/
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void get_random_bytes ( void *buf, size_t len )
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{
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u8 *bufp = buf;
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/*
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* Somewhat arbitrarily, choose the 0x00FF0000-masked byte
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* returned by random() as having good entropy. PRNGs often
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* don't provide good entropy in lower bits, and the top byte
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* might show a pattern because of sign issues.
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*/
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while ( len-- ) {
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*bufp++ = ( random() >> 16 ) & 0xFF;
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}
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}
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