d4af9e693f
I have worked hard to reduce diffs against the vendor branch. One notable change in that respect is that we no longer prefer DSA over RSA - the reasons for doing so went away years ago. This may cause some surprises, as ssh will warn about unknown host keys even for hosts whose keys haven't changed. MFC after: 6 weeks
151 lines
3.5 KiB
C
151 lines
3.5 KiB
C
/*
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* Copyright (c) 1999,2000,2004 Damien Miller <djm@mindrot.org>
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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#include "includes.h"
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#include <sys/types.h>
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#include <string.h>
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#include <stdlib.h>
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#include <stdarg.h>
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#include "log.h"
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#ifndef HAVE_ARC4RANDOM
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#include <openssl/rand.h>
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#include <openssl/rc4.h>
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#include <openssl/err.h>
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/* Size of key to use */
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#define SEED_SIZE 20
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/* Number of bytes to reseed after */
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#define REKEY_BYTES (1 << 24)
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static int rc4_ready = 0;
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static RC4_KEY rc4;
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unsigned int
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arc4random(void)
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{
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unsigned int r = 0;
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static int first_time = 1;
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if (rc4_ready <= 0) {
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if (first_time)
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seed_rng();
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first_time = 0;
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arc4random_stir();
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}
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RC4(&rc4, sizeof(r), (unsigned char *)&r, (unsigned char *)&r);
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rc4_ready -= sizeof(r);
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return(r);
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}
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void
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arc4random_stir(void)
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{
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unsigned char rand_buf[SEED_SIZE];
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int i;
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memset(&rc4, 0, sizeof(rc4));
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if (RAND_bytes(rand_buf, sizeof(rand_buf)) <= 0)
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fatal("Couldn't obtain random bytes (error %ld)",
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ERR_get_error());
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RC4_set_key(&rc4, sizeof(rand_buf), rand_buf);
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/*
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* Discard early keystream, as per recommendations in:
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* http://www.wisdom.weizmann.ac.il/~itsik/RC4/Papers/Rc4_ksa.ps
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*/
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for(i = 0; i <= 256; i += sizeof(rand_buf))
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RC4(&rc4, sizeof(rand_buf), rand_buf, rand_buf);
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memset(rand_buf, 0, sizeof(rand_buf));
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rc4_ready = REKEY_BYTES;
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}
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#endif /* !HAVE_ARC4RANDOM */
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#ifndef ARC4RANDOM_BUF
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void
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arc4random_buf(void *_buf, size_t n)
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{
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size_t i;
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u_int32_t r = 0;
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char *buf = (char *)_buf;
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for (i = 0; i < n; i++) {
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if (i % 4 == 0)
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r = arc4random();
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buf[i] = r & 0xff;
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r >>= 8;
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}
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i = r = 0;
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}
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#endif /* !HAVE_ARC4RANDOM_BUF */
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#ifndef ARC4RANDOM_UNIFORM
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/*
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* Calculate a uniformly distributed random number less than upper_bound
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* avoiding "modulo bias".
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*
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* Uniformity is achieved by generating new random numbers until the one
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* returned is outside the range [0, 2**32 % upper_bound). This
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* guarantees the selected random number will be inside
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* [2**32 % upper_bound, 2**32) which maps back to [0, upper_bound)
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* after reduction modulo upper_bound.
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*/
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u_int32_t
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arc4random_uniform(u_int32_t upper_bound)
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{
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u_int32_t r, min;
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if (upper_bound < 2)
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return 0;
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#if (ULONG_MAX > 0xffffffffUL)
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min = 0x100000000UL % upper_bound;
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#else
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/* Calculate (2**32 % upper_bound) avoiding 64-bit math */
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if (upper_bound > 0x80000000)
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min = 1 + ~upper_bound; /* 2**32 - upper_bound */
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else {
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/* (2**32 - (x * 2)) % x == 2**32 % x when x <= 2**31 */
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min = ((0xffffffff - (upper_bound * 2)) + 1) % upper_bound;
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}
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#endif
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/*
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* This could theoretically loop forever but each retry has
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* p > 0.5 (worst case, usually far better) of selecting a
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* number inside the range we need, so it should rarely need
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* to re-roll.
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*/
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for (;;) {
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r = arc4random();
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if (r >= min)
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break;
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}
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return r % upper_bound;
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}
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#endif /* !HAVE_ARC4RANDOM_UNIFORM */
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