diff options
Diffstat (limited to 'contrib/syslinux-4.02/gpxe/src/crypto/crandom.c')
-rw-r--r-- | contrib/syslinux-4.02/gpxe/src/crypto/crandom.c | 55 |
1 files changed, 55 insertions, 0 deletions
diff --git a/contrib/syslinux-4.02/gpxe/src/crypto/crandom.c b/contrib/syslinux-4.02/gpxe/src/crypto/crandom.c new file mode 100644 index 0000000..9828482 --- /dev/null +++ b/contrib/syslinux-4.02/gpxe/src/crypto/crandom.c @@ -0,0 +1,55 @@ +/* + * Copyright (c) 2009 Joshua Oreman <oremanj@rwcr.net>. + * + * 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., 675 Mass Ave, Cambridge, MA 02139, USA. + */ + +FILE_LICENCE ( GPL2_OR_LATER ); + +/** @file + * + * Cryptographically strong random number generator + * + * Currently the cryptographic part is not implemented, and this just + * uses random(). + */ + +#include <gpxe/crypto.h> +#include <stdlib.h> + +/** + * Get cryptographically strong random bytes + * + * @v buf Buffer in which to store random bytes + * @v len Number of random bytes to generate + * + * @b WARNING: This function is currently underimplemented, and does + * not give numbers any stronger than random()! + */ +void get_random_bytes ( void *buf, size_t len ) +{ + u8 *bufp = buf; + + /* + * Somewhat arbitrarily, choose the 0x00FF0000-masked byte + * returned by random() as having good entropy. PRNGs often + * don't provide good entropy in lower bits, and the top byte + * might show a pattern because of sign issues. + */ + + while ( len-- ) { + *bufp++ = ( random() >> 16 ) & 0xFF; + } +} |