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73 lines
1.7 KiB
C
73 lines
1.7 KiB
C
/*
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* random.c -- get random bytes
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*
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* Copyright (C) 2010 Free Software Initiative of Japan
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* Author: NIIBE Yutaka <gniibe@fsij.org>
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*
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* This file is a part of Gnuk, a GnuPG USB Token implementation.
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*
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* Gnuk is free software: you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* Gnuk is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
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* 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, see <http://www.gnu.org/licenses/>.
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*
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*/
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#include "config.h"
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#include "ch.h"
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#include "gnuk.h"
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extern void *_binary_random_bits_start;
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const uint8_t *
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random_bytes_get (void)
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{
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uint32_t addr, addr0;
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addr = (uint32_t)&_binary_random_bits_start + ((hardclock () << 5) & 0x3e0);
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addr0 = addr;
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while (1)
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{
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if (*(uint32_t *)addr != 0)
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break;
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addr += 32;
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if (addr >= ((uint32_t)&_binary_random_bits_start) + 1024)
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addr = ((uint32_t)&_binary_random_bits_start);
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if (addr == addr0)
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fatal (FATAL_RANDOM);
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}
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return (const uint8_t *)addr;
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}
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void
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random_bytes_free (const uint8_t *p)
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{
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int i;
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uint32_t addr = (uint32_t)p;
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for (i = 0; i < 16; i++)
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flash_clear_halfword (addr+i*2);
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}
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uint32_t
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get_random (void)
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{
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const uint32_t *p = (const uint32_t *)random_bytes_get ();
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uint32_t r = *p;
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random_bytes_free ((const uint8_t *)p);
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return r;
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}
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