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1) Update copyright notice.

Browse Source 
2) Eliminate "struct arc4_stream *as" arg since only single arg is
possible.
3) Set rs.j = rs.i after arc4random key schedule to be more like arc4
stream cipher.

Obtained from:  OpenBSD
This commit is contained in:
Andrey A. Chernov 2008-07-21 20:04:32 +00:00
parent 847bd80810
commit 860c4e582a
1 changed files with 53 additions and 43 deletions
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96
lib/libc/gen/arc4random.c
View File

@ -1,14 +1,23 @@
/*
* Arc4 random number generator for OpenBSD.
* Copyright 1996 David Mazieres <dm@lcs.mit.edu>.
* Copyright (c) 1996, David Mazieres <dm@uun.org>
* Copyright (c) 2008, Damien Miller <djm@openbsd.org>
*
* Modification and redistribution in source and binary forms is
* permitted provided that due credit is given to the author and the
* OpenBSD project (for instance by leaving this copyright notice
* intact).
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
/*
* Arc4 random number generator for OpenBSD.
*
* This code is derived from section 17.1 of Applied Cryptography,
* second edition, which describes a stream cipher allegedly
* compatible with RSA Labs "RC4" cipher (the actual description of
@ -63,38 +72,39 @@ static int rs_initialized;
static int rs_stired;
static int arc4_count;
static inline u_int8_t arc4_getbyte(struct arc4_stream *);
static void arc4_stir(struct arc4_stream *);
static inline u_int8_t arc4_getbyte(void);
static void arc4_stir(void);
static inline void
arc4_init(struct arc4_stream *as)
arc4_init(void)
{
int n;
for (n = 0; n < 256; n++)
as->s[n] = n;
as->i = 0;
as->j = 0;
rs.s[n] = n;
rs.i = 0;
rs.j = 0;
}
static inline void
arc4_addrandom(struct arc4_stream *as, u_char *dat, int datlen)
arc4_addrandom(u_char *dat, int datlen)
{
int n;
u_int8_t si;
as->i--;
rs.i--;
for (n = 0; n < 256; n++) {
as->i = (as->i + 1);
si = as->s[as->i];
as->j = (as->j + si + dat[n % datlen]);
as->s[as->i] = as->s[as->j];
as->s[as->j] = si;
rs.i = (rs.i + 1);
si = rs.s[rs.i];
rs.j = (rs.j + si + dat[n % datlen]);
rs.s[rs.i] = rs.s[rs.j];
rs.s[rs.j] = si;
}
rs.j = rs.i;
}
static void
arc4_stir(struct arc4_stream *as)
arc4_stir(void)
{
int fd, n;
struct {
@ -107,13 +117,13 @@ arc4_stir(struct arc4_stream *as)
rdat.pid = getpid();
fd = _open(RANDOMDEV, O_RDONLY, 0);
if (fd >= 0) {
(void) _read(fd, rdat.rnd, sizeof(rdat.rnd));
_close(fd);
(void)_read(fd, rdat.rnd, sizeof(rdat.rnd));
(void)_close(fd);
}
/* fd < 0? Ah, what the heck. We'll just take whatever was on the
* stack... */
arc4_addrandom(as, (void *) &rdat, sizeof(rdat));
arc4_addrandom((u_char *)&rdat, sizeof(rdat));
/*
* Throw away the first N bytes of output, as suggested in the
@ -123,34 +133,34 @@ arc4_stir(struct arc4_stream *as)
* by Ilya Mironov.
*/
for (n = 0; n < 1024; n++)
(void) arc4_getbyte(as);
(void)arc4_getbyte();
arc4_count = 1600000;
}
static inline u_int8_t
arc4_getbyte(struct arc4_stream *as)
arc4_getbyte(void)
{
u_int8_t si, sj;
as->i = (as->i + 1);
si = as->s[as->i];
as->j = (as->j + si);
sj = as->s[as->j];
as->s[as->i] = sj;
as->s[as->j] = si;
rs.i = (rs.i + 1);
si = rs.s[rs.i];
rs.j = (rs.j + si);
sj = rs.s[rs.j];
rs.s[rs.i] = sj;
rs.s[rs.j] = si;
return (as->s[(si + sj) & 0xff]);
return (rs.s[(si + sj) & 0xff]);
}
static inline u_int32_t
arc4_getword(struct arc4_stream *as)
arc4_getword(void)
{
u_int32_t val;
val = arc4_getbyte(as) << 24;
val |= arc4_getbyte(as) << 16;
val |= arc4_getbyte(as) << 8;
val |= arc4_getbyte(as);
val = arc4_getbyte() << 24;
val |= arc4_getbyte() << 16;
val |= arc4_getbyte() << 8;
val |= arc4_getbyte();
return (val);
}
@ -159,7 +169,7 @@ static void
arc4_check_init(void)
{
if (!rs_initialized) {
arc4_init(&rs);
arc4_init();
rs_initialized = 1;
}
}
@ -168,7 +178,7 @@ static inline void
arc4_check_stir(void)
{
if (!rs_stired || arc4_count <= 0) {
arc4_stir(&rs);
arc4_stir();
rs_stired = 1;
}
}
@ -178,7 +188,7 @@ arc4random_stir(void)
{
THREAD_LOCK();
arc4_check_init();
arc4_stir(&rs);
arc4_stir();
rs_stired = 1;
THREAD_UNLOCK();
}
@ -189,7 +199,7 @@ arc4random_addrandom(u_char *dat, int datlen)
THREAD_LOCK();
arc4_check_init();
arc4_check_stir();
arc4_addrandom(&rs, dat, datlen);
arc4_addrandom(dat, datlen);
THREAD_UNLOCK();
}
@ -201,7 +211,7 @@ arc4random(void)
THREAD_LOCK();
arc4_check_init();
arc4_check_stir();
rnd = arc4_getword(&rs);
rnd = arc4_getword();
arc4_count -= 4;
THREAD_UNLOCK();
@ -217,7 +227,7 @@ arc4random_buf(void *_buf, size_t n)
arc4_check_init();
while (n--) {
arc4_check_stir();
buf[n] = arc4_getbyte(&rs);
buf[n] = arc4_getbyte();
arc4_count--;
}
THREAD_UNLOCK();