433 lines
12 KiB
C
433 lines
12 KiB
C
/*
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* random.c -- A strong random number generator
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*
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* $Id: random.c,v 1.2 1995/11/04 16:00:50 markm Exp $
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*
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* Version 0.92, last modified 21-Sep-95
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*
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* Copyright Theodore Ts'o, 1994, 1995. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, and the entire permission notice in its entirety,
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* including the disclaimer of warranties.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote
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* products derived from this software without specific prior
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* written permission.
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*
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* ALTERNATIVELY, this product may be distributed under the terms of
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* the GNU Public License, in which case the provisions of the GPL are
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* required INSTEAD OF the above restrictions. (This clause is
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* necessary due to a potential bad interaction between the GPL and
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* the restrictions contained in a BSD-style copyright.)
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*
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* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
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* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
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* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
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* OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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*/
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#include <sys/param.h>
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#include <sys/cdefs.h>
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#include <sys/kernel.h>
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#include <sys/uio.h>
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#include <sys/systm.h>
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#include <i386/isa/isa.h>
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#include <i386/isa/icu.h>
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#include <i386/isa/timerreg.h>
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#include <i386/isa/isa_device.h>
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#include <machine/random.h>
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#define RANDPOOL 512
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struct random_bucket {
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int add_ptr;
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int entropy_count;
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int length;
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int bit_length;
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int delay_mix:1;
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u_int8_t *pool;
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};
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struct timer_rand_state {
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u_int32_t last_time;
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int last_delta;
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int nbits;
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};
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static struct random_bucket random_state;
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static u_int32_t rand_pool_key[16];
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static u_int8_t random_pool[RANDPOOL];
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static u_int32_t random_counter[16];
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static struct timer_rand_state keyboard_timer_state;
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static struct timer_rand_state irq_timer_state[ICU_LEN];
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inthand2_t add_interrupt_randomness;
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u_int16_t interrupt_allowed = 0;
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#ifndef MIN
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#define MIN(a,b) (((a) < (b)) ? (a) : (b))
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#endif
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static void
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flush_random(struct random_bucket *random_state)
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{
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random_state->add_ptr = 0;
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random_state->bit_length = random_state->length * 8;
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random_state->entropy_count = 0;
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random_state->delay_mix = 0;
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}
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void
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rand_initialize(void)
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{
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random_state.length = RANDPOOL;
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random_state.pool = random_pool;
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flush_random(&random_state);
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#if 0
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{
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int irq;
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long interrupts;
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/* XXX Dreadful hack - should be replaced by something more elegant */
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interrupts = RANDOM_INTERRUPTS;
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for (irq = 0; irq < ICU_LEN; irq++) {
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interrupt_allowed[irq] = interrupts & 0x0001;
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interrupts >>= 1;
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printf("Randomising irq %d %s\n", irq, interrupt_allowed[irq] ?
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"on" : "off");
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}
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}
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#endif
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}
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/*
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* MD5 transform algorithm, taken from code written by Colin Plumb,
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* and put into the public domain
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*/
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/* The four core functions - F1 is optimized somewhat */
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/* #define F1(x, y, z) (x & y | ~x & z) */
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#define F1(x, y, z) (z ^ (x & (y ^ z)))
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#define F2(x, y, z) F1(z, x, y)
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#define F3(x, y, z) (x ^ y ^ z)
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#define F4(x, y, z) (y ^ (x | ~z))
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/* This is the central step in the MD5 algorithm. */
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#define MD5STEP(f, w, x, y, z, data, s) \
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( w += f(x, y, z) + data, w = w<<s | w>>(32-s), w += x )
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/*
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* The core of the MD5 algorithm, this alters an existing MD5 hash to
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* reflect the addition of 16 longwords of new data. MD5Update blocks
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* the data and converts bytes into longwords for this routine.
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*/
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static void
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MD5Transform(u_int32_t buf[4], u_int32_t const in[16])
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{
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u_int32_t a, b, c, d;
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a = buf[0];
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b = buf[1];
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c = buf[2];
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d = buf[3];
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MD5STEP(F1, a, b, c, d, in[ 0]+0xd76aa478, 7);
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MD5STEP(F1, d, a, b, c, in[ 1]+0xe8c7b756, 12);
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MD5STEP(F1, c, d, a, b, in[ 2]+0x242070db, 17);
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MD5STEP(F1, b, c, d, a, in[ 3]+0xc1bdceee, 22);
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MD5STEP(F1, a, b, c, d, in[ 4]+0xf57c0faf, 7);
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MD5STEP(F1, d, a, b, c, in[ 5]+0x4787c62a, 12);
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MD5STEP(F1, c, d, a, b, in[ 6]+0xa8304613, 17);
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MD5STEP(F1, b, c, d, a, in[ 7]+0xfd469501, 22);
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MD5STEP(F1, a, b, c, d, in[ 8]+0x698098d8, 7);
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MD5STEP(F1, d, a, b, c, in[ 9]+0x8b44f7af, 12);
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MD5STEP(F1, c, d, a, b, in[10]+0xffff5bb1, 17);
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MD5STEP(F1, b, c, d, a, in[11]+0x895cd7be, 22);
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MD5STEP(F1, a, b, c, d, in[12]+0x6b901122, 7);
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MD5STEP(F1, d, a, b, c, in[13]+0xfd987193, 12);
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MD5STEP(F1, c, d, a, b, in[14]+0xa679438e, 17);
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MD5STEP(F1, b, c, d, a, in[15]+0x49b40821, 22);
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MD5STEP(F2, a, b, c, d, in[ 1]+0xf61e2562, 5);
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MD5STEP(F2, d, a, b, c, in[ 6]+0xc040b340, 9);
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MD5STEP(F2, c, d, a, b, in[11]+0x265e5a51, 14);
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MD5STEP(F2, b, c, d, a, in[ 0]+0xe9b6c7aa, 20);
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MD5STEP(F2, a, b, c, d, in[ 5]+0xd62f105d, 5);
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MD5STEP(F2, d, a, b, c, in[10]+0x02441453, 9);
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MD5STEP(F2, c, d, a, b, in[15]+0xd8a1e681, 14);
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MD5STEP(F2, b, c, d, a, in[ 4]+0xe7d3fbc8, 20);
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MD5STEP(F2, a, b, c, d, in[ 9]+0x21e1cde6, 5);
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MD5STEP(F2, d, a, b, c, in[14]+0xc33707d6, 9);
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MD5STEP(F2, c, d, a, b, in[ 3]+0xf4d50d87, 14);
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MD5STEP(F2, b, c, d, a, in[ 8]+0x455a14ed, 20);
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MD5STEP(F2, a, b, c, d, in[13]+0xa9e3e905, 5);
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MD5STEP(F2, d, a, b, c, in[ 2]+0xfcefa3f8, 9);
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MD5STEP(F2, c, d, a, b, in[ 7]+0x676f02d9, 14);
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MD5STEP(F2, b, c, d, a, in[12]+0x8d2a4c8a, 20);
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MD5STEP(F3, a, b, c, d, in[ 5]+0xfffa3942, 4);
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MD5STEP(F3, d, a, b, c, in[ 8]+0x8771f681, 11);
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MD5STEP(F3, c, d, a, b, in[11]+0x6d9d6122, 16);
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MD5STEP(F3, b, c, d, a, in[14]+0xfde5380c, 23);
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MD5STEP(F3, a, b, c, d, in[ 1]+0xa4beea44, 4);
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MD5STEP(F3, d, a, b, c, in[ 4]+0x4bdecfa9, 11);
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MD5STEP(F3, c, d, a, b, in[ 7]+0xf6bb4b60, 16);
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MD5STEP(F3, b, c, d, a, in[10]+0xbebfbc70, 23);
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MD5STEP(F3, a, b, c, d, in[13]+0x289b7ec6, 4);
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MD5STEP(F3, d, a, b, c, in[ 0]+0xeaa127fa, 11);
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MD5STEP(F3, c, d, a, b, in[ 3]+0xd4ef3085, 16);
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MD5STEP(F3, b, c, d, a, in[ 6]+0x04881d05, 23);
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MD5STEP(F3, a, b, c, d, in[ 9]+0xd9d4d039, 4);
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MD5STEP(F3, d, a, b, c, in[12]+0xe6db99e5, 11);
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MD5STEP(F3, c, d, a, b, in[15]+0x1fa27cf8, 16);
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MD5STEP(F3, b, c, d, a, in[ 2]+0xc4ac5665, 23);
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MD5STEP(F4, a, b, c, d, in[ 0]+0xf4292244, 6);
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MD5STEP(F4, d, a, b, c, in[ 7]+0x432aff97, 10);
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MD5STEP(F4, c, d, a, b, in[14]+0xab9423a7, 15);
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MD5STEP(F4, b, c, d, a, in[ 5]+0xfc93a039, 21);
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MD5STEP(F4, a, b, c, d, in[12]+0x655b59c3, 6);
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MD5STEP(F4, d, a, b, c, in[ 3]+0x8f0ccc92, 10);
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MD5STEP(F4, c, d, a, b, in[10]+0xffeff47d, 15);
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MD5STEP(F4, b, c, d, a, in[ 1]+0x85845dd1, 21);
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MD5STEP(F4, a, b, c, d, in[ 8]+0x6fa87e4f, 6);
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MD5STEP(F4, d, a, b, c, in[15]+0xfe2ce6e0, 10);
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MD5STEP(F4, c, d, a, b, in[ 6]+0xa3014314, 15);
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MD5STEP(F4, b, c, d, a, in[13]+0x4e0811a1, 21);
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MD5STEP(F4, a, b, c, d, in[ 4]+0xf7537e82, 6);
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MD5STEP(F4, d, a, b, c, in[11]+0xbd3af235, 10);
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MD5STEP(F4, c, d, a, b, in[ 2]+0x2ad7d2bb, 15);
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MD5STEP(F4, b, c, d, a, in[ 9]+0xeb86d391, 21);
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buf[0] += a;
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buf[1] += b;
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buf[2] += c;
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buf[3] += d;
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}
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#undef F1
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#undef F2
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#undef F3
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#undef F4
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#undef MD5STEP
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static void
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mix_bucket(struct random_bucket *v)
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{
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struct random_bucket *r = v;
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int i, num_passes;
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u_int32_t *p;
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u_int32_t iv[4];
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r->delay_mix = 0;
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/* Start IV from last block of the random pool */
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memcpy(iv, r->pool + r->length - sizeof(iv), sizeof(iv));
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num_passes = r->length / 16;
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for (i = 0, p = (u_int32_t *) r->pool; i < num_passes; i++) {
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MD5Transform(iv, rand_pool_key);
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iv[0] = (*p++ ^= iv[0]);
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iv[1] = (*p++ ^= iv[1]);
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iv[2] = (*p++ ^= iv[2]);
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iv[3] = (*p++ ^= iv[3]);
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}
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memcpy(rand_pool_key, r->pool, sizeof(rand_pool_key));
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/* Wipe iv from memory */
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bzero(iv, sizeof(iv));
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r->add_ptr = 0;
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}
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/*
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* This function adds a byte into the entropy "pool". It does not
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* update the entropy estimate. The caller must do this if appropriate.
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*/
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static inline void
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add_entropy_byte(struct random_bucket *r, const u_int8_t ch, int delay)
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{
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if (!delay && r->delay_mix)
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mix_bucket(r);
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r->pool[r->add_ptr++] ^= ch;
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if (r->add_ptr >= r->length) {
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if (delay) {
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r->delay_mix = 1;
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r->add_ptr = 0;
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} else
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mix_bucket(r);
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}
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}
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/*
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* This function adds some number of bytes into the entropy pool and
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* updates the entropy count as appropriate.
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*/
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static void
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add_entropy(struct random_bucket *r, const u_int8_t *ptr, int length,
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int entropy_level, int delay)
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{
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while (length-- > 0)
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add_entropy_byte(r, *ptr++, delay);
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r->entropy_count += entropy_level;
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if (r->entropy_count > r->length*8)
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r->entropy_count = r->length * 8;
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}
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/*
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* This function adds entropy to the entropy "pool" by using timing
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* delays. It uses the timer_rand_state structure to make an estimate
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* of how many bits of entropy this call has added to the pool.
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*/
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static void
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add_timer_randomness(struct random_bucket *r, struct timer_rand_state *state,
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int delay)
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{
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int delta, delta2;
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int nbits;
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/*
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* Calculate number of bits of randomness we probably
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* added. We take into account the first and second order
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* delta's in order to make our estimate.
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*/
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delta = ticks - state->last_time;
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delta2 = delta - state->last_delta;
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state->last_time = ticks;
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state->last_delta = delta;
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if (delta < 0) delta = -delta;
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if (delta2 < 0) delta2 = -delta2;
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delta = MIN(delta, delta2) >> 1;
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for (nbits = 0; delta; nbits++)
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delta >>= 1;
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add_entropy(r, (u_int8_t *) &ticks, sizeof(ticks), nbits, delay);
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#if defined (__i386__)
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/*
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* On a 386, read the high resolution timer. We assume that
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* this gives us 2 bits of randomness. XXX This needs
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* investigation.
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*/
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outb(TIMER_LATCH|TIMER_SEL0, TIMER_MODE); /* latch the count ASAP */
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add_entropy_byte(r, inb(TIMER_CNTR0), 1);
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add_entropy_byte(r, inb(TIMER_CNTR0), 1);
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r->entropy_count += 2;
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if (r->entropy_count > r->bit_length)
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r->entropy_count = r->bit_length;
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#endif
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}
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void
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add_keyboard_randomness(u_char scancode)
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{
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struct random_bucket *r = &random_state;
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add_timer_randomness(r, &keyboard_timer_state, 0);
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add_entropy_byte(r, scancode, 0);
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r->entropy_count += 6;
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if (r->entropy_count > r->bit_length)
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r->entropy_count = r->bit_length;
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}
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void
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add_interrupt_randomness(int irq)
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{
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static struct random_bucket *r = &random_state;
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u_int16_t intbit = 1 << irq;
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/* printf("Trapping interrupt %d\n", irq); */
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if (interrupt_allowed & intbit)
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add_timer_randomness(r, &irq_timer_state[irq], 1);
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}
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/*
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* This function extracts randomness from the "entropy pool", and
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* returns it in a buffer. This function computes how many remaining
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* bits of entropy are left in the pool, but it does not restrict the
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* number of bytes that are actually obtained.
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*/
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static inline u_int
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extract_entropy(struct random_bucket *r, char *buf, u_int nbytes)
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{
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int passes, i;
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u_int length, ret;
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u_int32_t tmp[4];
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u_int8_t *cp;
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add_entropy(r, (u_int8_t *) &ticks, sizeof(ticks), 0, 0);
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if (r->entropy_count > r->bit_length)
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r->entropy_count = r->bit_length;
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if (nbytes > 32768)
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nbytes = 32768;
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ret = nbytes;
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r->entropy_count -= ret * 8;
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if (r->entropy_count < 0)
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r->entropy_count = 0;
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passes = r->length / 64;
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while (nbytes) {
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length = MIN(nbytes, 16);
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for (i=0; i < 16; i++) {
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if (++random_counter[i] != 0)
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break;
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}
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tmp[0] = 0x67452301;
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tmp[1] = 0xefcdab89;
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tmp[2] = 0x98badcfe;
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tmp[3] = 0x10325476;
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MD5Transform(tmp, random_counter);
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for (i = 0, cp = r->pool; i < passes; i++, cp+=64)
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MD5Transform(tmp, (u_int32_t *) cp);
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memcpy(buf, tmp, length);
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nbytes -= length;
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buf += length;
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}
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return ret;
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}
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/*
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* This function is the exported kernel interface. It returns some
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* number of good random numbers, suitable for seeding TCP sequence
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* numbers, etc.
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*/
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void
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get_random_bytes(void *buf, u_int nbytes)
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{
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extract_entropy(&random_state, (char *) buf, nbytes);
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}
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u_int
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read_random(char * buf, u_int nbytes)
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{
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if ((nbytes * 8) > random_state.entropy_count)
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nbytes = random_state.entropy_count / 8;
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return extract_entropy(&random_state, buf, nbytes);
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}
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u_int
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read_random_unlimited(char * buf, u_int nbytes)
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{
|
|
return extract_entropy(&random_state, buf, nbytes);
|
|
}
|