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/*
* Copyright (C) 2012 Michael Brown <mbrown@fensystems.co.uk>.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of the
* License, or any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA.
*/
FILE_LICENCE ( GPL2_OR_LATER );
/** @file
*
* Random non-zero bytes
*
* The RSA algorithm requires the generation of random non-zero bytes,
* i.e. bytes in the range [0x01,0xff].
*
* This algorithm is designed to comply with ANS X9.82 Part 1-2006
* Section 9.2.1. This standard is not freely available, but most of
* the text appears to be shared with NIST SP 800-90, which can be
* downloaded from
*
* http://csrc.nist.gov/publications/nistpubs/800-90/SP800-90revised_March2007.pdf
*
* Where possible, references are given to both documents. In the
* case of any disagreement, ANS X9.82 takes priority over NIST SP
* 800-90. (In particular, note that some algorithms that are
* Approved by NIST SP 800-90 are not Approved by ANS X9.82.)
*/
#include <stddef.h>
#include <stdint.h>
#include <ipxe/rbg.h>
#include <ipxe/random_nz.h>
/**
* Get random non-zero bytes
*
* @v data Output buffer
* @v len Length of output buffer
* @ret rc Return status code
*
* This algorithm is designed to be isomorphic to the Simple Discard
* Method described in ANS X9.82 Part 1-2006 Section 9.2.1 (NIST SP
* 800-90 Section B.5.1.1).
*/
int get_random_nz ( void *data, size_t len ) {
uint8_t *bytes = data;
int rc;
while ( len ) {
/* Generate random byte */
if ( ( rc = rbg_generate ( NULL, 0, 0, bytes, 1 ) ) != 0 )
return rc;
/* Move to next byte if this byte is acceptable */
if ( *bytes != 0 ) {
bytes++;
len--;
}
}
return 0;
}
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