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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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+
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+FILE_LICENCE ( GPL2_OR_LATER );
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+
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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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+
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+#include <gpxe/crypto.h>
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+#include <stdlib.h>
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+
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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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+ /*
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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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+
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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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