bbf09ad887
one out of a block cipher. This has 2 advantages: 1) The code is _much_ simpler 2) We aren't committing our security to one algorithm (much as we may think we trust AES). While I'm here, make an explicit reseed do a slow reseed instead of a fast; this is in line with what the original paper suggested.
347 lines
9.6 KiB
C
347 lines
9.6 KiB
C
/*-
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* Copyright (c) 2000 Mark R V Murray
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* 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, this list of conditions and the following disclaimer
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* in this position and unchanged.
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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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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/kernel.h>
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#include <sys/lock.h>
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#include <sys/mutex.h>
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#include <sys/random.h>
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#include <sys/sysctl.h>
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#include <crypto/rijndael/rijndael.h>
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#include <crypto/sha2/sha2.h>
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#include <dev/random/hash.h>
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#include <dev/random/randomdev.h>
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#include <dev/random/yarrow.h>
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/* #define DEBUG */
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RANDOM_CHECK_UINT(gengateinterval, 4, 64);
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RANDOM_CHECK_UINT(bins, 2, 16);
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RANDOM_CHECK_UINT(fastthresh, BLOCKSIZE/4, BLOCKSIZE);
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RANDOM_CHECK_UINT(slowthresh, BLOCKSIZE/4, BLOCKSIZE);
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RANDOM_CHECK_UINT(slowoverthresh, 1, 5);
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/* Structure holding the entropy state */
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static struct random_state random_state;
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SYSCTL_NODE(_kern_random, OID_AUTO, yarrow, CTLFLAG_RW, 0, "Yarrow Parameters");
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SYSCTL_PROC(_kern_random_yarrow, OID_AUTO, gengateinterval,
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CTLTYPE_INT|CTLFLAG_RW, &random_state.gengateinterval, 10,
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random_check_uint_gengateinterval, "I", "Generator Gate Interval");
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SYSCTL_PROC(_kern_random_yarrow, OID_AUTO, bins,
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CTLTYPE_INT|CTLFLAG_RW, &random_state.bins, 10,
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random_check_uint_bins, "I", "Execution time tuner");
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SYSCTL_PROC(_kern_random_yarrow, OID_AUTO, fastthresh,
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CTLTYPE_INT|CTLFLAG_RW, &random_state.pool[0].thresh, (3*BLOCKSIZE)/4,
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random_check_uint_fastthresh, "I", "Fast reseed threshold");
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SYSCTL_PROC(_kern_random_yarrow, OID_AUTO, slowthresh,
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CTLTYPE_INT|CTLFLAG_RW, &random_state.pool[1].thresh, BLOCKSIZE,
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random_check_uint_slowthresh, "I", "Slow reseed threshold");
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SYSCTL_PROC(_kern_random_yarrow, OID_AUTO, slowoverthresh,
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CTLTYPE_INT|CTLFLAG_RW, &random_state.slowoverthresh, 2,
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random_check_uint_slowoverthresh, "I", "Slow over-threshold reseed");
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static void generator_gate(void);
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static void reseed(u_int);
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/* The reseed thread mutex */
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static struct mtx random_reseed_mtx;
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/* Process a single stochastic event off the harvest queue */
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void
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random_process_event(struct harvest *event)
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{
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u_int pl, overthreshhold[2];
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struct source *source;
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enum esource src;
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/* Unpack the event into the appropriate source accumulator */
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pl = random_state.which;
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source = &random_state.pool[pl].source[event->source];
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yarrow_hash_iterate(&random_state.pool[pl].hash, event->entropy,
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sizeof(event->entropy));
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yarrow_hash_iterate(&random_state.pool[pl].hash, &event->somecounter,
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sizeof(event->somecounter));
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source->frac += event->frac;
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source->bits += event->bits + source->frac/1024;
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source->frac %= 1024;
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/* Count the over-threshold sources in each pool */
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for (pl = 0; pl < 2; pl++) {
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overthreshhold[pl] = 0;
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for (src = RANDOM_START; src < ENTROPYSOURCE; src++) {
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if (random_state.pool[pl].source[src].bits
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> random_state.pool[pl].thresh)
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overthreshhold[pl]++;
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}
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}
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/* if any fast source over threshhold, reseed */
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if (overthreshhold[FAST])
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reseed(FAST);
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/* if enough slow sources are over threshhold, reseed */
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if (overthreshhold[SLOW] >= random_state.slowoverthresh)
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reseed(SLOW);
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/* Invert the fast/slow pool selector bit */
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random_state.which = !random_state.which;
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}
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void
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random_init(void)
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{
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int i;
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/* Yarrow parameters. Do not adjust these unless you have
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* have a very good clue about what they do!
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*/
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random_state.gengateinterval = 10;
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random_state.bins = 10;
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random_state.pool[0].thresh = (3*BLOCKSIZE)/4;
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random_state.pool[1].thresh = BLOCKSIZE;
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random_state.slowoverthresh = 2;
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random_state.which = FAST;
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/* Initialise the fast and slow entropy pools */
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for (i = 0; i < 2; i++)
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yarrow_hash_init(&random_state.pool[i].hash);
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/* Clear the counter */
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for (i = 0; i < 4; i++)
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random_state.counter[i] = 0;
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/* Set up a lock for the reseed process */
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mtx_init(&random_reseed_mtx, "random reseed", NULL, MTX_DEF);
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}
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void
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random_deinit(void)
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{
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mtx_destroy(&random_reseed_mtx);
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}
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static void
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reseed(u_int fastslow)
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{
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/* Interrupt-context stack is a limited resource; make large
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* structures static.
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*/
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static u_char v[TIMEBIN][KEYSIZE]; /* v[i] */
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static struct yarrowhash context;
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u_char hash[KEYSIZE]; /* h' */
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u_char temp[KEYSIZE];
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u_int i;
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enum esource j;
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#ifdef DEBUG
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mtx_lock(&Giant);
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printf("Reseed type %d\n", fastslow);
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mtx_unlock(&Giant);
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#endif
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/* The reseed task must not be jumped on */
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mtx_lock(&random_reseed_mtx);
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/* 1. Hash the accumulated entropy into v[0] */
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yarrow_hash_init(&context);
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/* Feed the slow pool hash in if slow */
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if (fastslow == SLOW)
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yarrow_hash_iterate(&context,
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&random_state.pool[SLOW].hash,
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sizeof(struct yarrowhash));
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yarrow_hash_iterate(&context,
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&random_state.pool[FAST].hash, sizeof(struct yarrowhash));
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yarrow_hash_finish(&context, v[0]);
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/* 2. Compute hash values for all v. _Supposed_ to be computationally
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* intensive.
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*/
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if (random_state.bins > TIMEBIN)
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random_state.bins = TIMEBIN;
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for (i = 1; i < random_state.bins; i++) {
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yarrow_hash_init(&context);
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/* v[i] #= h(v[i - 1]) */
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yarrow_hash_iterate(&context, v[i - 1], KEYSIZE);
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/* v[i] #= h(v[0]) */
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yarrow_hash_iterate(&context, v[0], KEYSIZE);
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/* v[i] #= h(i) */
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yarrow_hash_iterate(&context, &i, sizeof(u_int));
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/* Return the hashval */
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yarrow_hash_finish(&context, v[i]);
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}
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/* 3. Compute a new key; h' is the identity function here;
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* it is not being ignored!
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*/
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yarrow_hash_init(&context);
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yarrow_hash_iterate(&context, &random_state.key, KEYSIZE);
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for (i = 1; i < random_state.bins; i++)
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yarrow_hash_iterate(&context, &v[i], KEYSIZE);
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yarrow_hash_finish(&context, temp);
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yarrow_encrypt_init(&random_state.key, temp);
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/* 4. Recompute the counter */
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for (i = 0; i < 4; i++)
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random_state.counter[i] = 0;
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yarrow_encrypt(&random_state.key, random_state.counter, temp);
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memcpy(random_state.counter, temp, sizeof(random_state.counter));
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/* 5. Reset entropy estimate accumulators to zero */
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for (i = 0; i <= fastslow; i++) {
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for (j = RANDOM_START; j < ENTROPYSOURCE; j++) {
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random_state.pool[i].source[j].bits = 0;
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random_state.pool[i].source[j].frac = 0;
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}
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}
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/* 6. Wipe memory of intermediate values */
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memset((void *)v, 0, sizeof(v));
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memset((void *)temp, 0, sizeof(temp));
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memset((void *)hash, 0, sizeof(hash));
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/* 7. Dump to seed file */
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/* XXX Not done here yet */
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/* Release the reseed mutex */
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mtx_unlock(&random_reseed_mtx);
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#ifdef DEBUG
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mtx_lock(&Giant);
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printf("Reseed finish\n");
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mtx_unlock(&Giant);
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#endif
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/* Unblock the device if it was blocked due to being unseeded */
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random_unblock();
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}
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/* Internal function to return processed entropy from the PRNG */
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int
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read_random_real(void *buf, int count)
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{
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static int cur = 0;
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static int gate = 1;
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static u_char genval[KEYSIZE];
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int i;
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int retval;
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/* The reseed task must not be jumped on */
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mtx_lock(&random_reseed_mtx);
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if (gate) {
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generator_gate();
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random_state.outputblocks = 0;
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gate = 0;
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}
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if (count > 0 && (size_t)count >= sizeof(random_state.counter)) {
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retval = 0;
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for (i = 0; i < count; i += (int)sizeof(random_state.counter)) {
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random_state.counter[0]++;
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yarrow_encrypt(&random_state.key, random_state.counter,
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genval);
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memcpy((char *)buf + i, genval,
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sizeof(random_state.counter));
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if (++random_state.outputblocks >=
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random_state.gengateinterval) {
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generator_gate();
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random_state.outputblocks = 0;
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}
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retval += (int)sizeof(random_state.counter);
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}
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}
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else {
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if (!cur) {
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random_state.counter[0]++;
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yarrow_encrypt(&random_state.key, random_state.counter,
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genval);
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memcpy(buf, genval, (size_t)count);
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cur = (int)sizeof(random_state.counter) - count;
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if (++random_state.outputblocks >=
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random_state.gengateinterval) {
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generator_gate();
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random_state.outputblocks = 0;
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}
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retval = count;
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}
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else {
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retval = cur < count ? cur : count;
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memcpy(buf,
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&genval[(int)sizeof(random_state.counter) - cur],
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(size_t)retval);
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cur -= retval;
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}
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}
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mtx_unlock(&random_reseed_mtx);
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return retval;
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}
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static void
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generator_gate(void)
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{
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u_int i;
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u_char temp[KEYSIZE];
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#ifdef DEBUG
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mtx_lock(&Giant);
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printf("Generator gate\n");
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mtx_unlock(&Giant);
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#endif
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for (i = 0; i < KEYSIZE; i += sizeof(random_state.counter)) {
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random_state.counter[0]++;
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yarrow_encrypt(&random_state.key, random_state.counter,
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&(temp[i]));
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}
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yarrow_encrypt_init(&random_state.key, temp);
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memset((void *)temp, 0, KEYSIZE);
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#ifdef DEBUG
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mtx_lock(&Giant);
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printf("Generator gate finish\n");
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mtx_unlock(&Giant);
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#endif
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}
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/* Helper routine to perform explicit reseeds */
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void
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random_reseed(void)
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{
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reseed(SLOW);
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}
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