1 /* $Id: arc4random.c 25705 2008-07-11 18:21:57Z androsyn $ */
2 /* $$$: arc4random.c 2005/02/08 robert */
3 /* $NetBSD: arc4random.c,v 1.5.2.1 2004/03/26 22:52:50 jmc Exp $ */
4 /* $OpenBSD: arc4random.c,v 1.6 2001/06/05 05:05:38 pvalchev Exp $ */
7 * Arc4 random number generator for OpenBSD.
8 * Copyright 1996 David Mazieres <dm@lcs.mit.edu>.
10 * Modification and redistribution in source and binary forms is
11 * permitted provided that due credit is given to the author and the
12 * OpenBSD project by leaving this copyright notice intact.
16 * This code is derived from section 17.1 of Applied Cryptography,
17 * second edition, which describes a stream cipher allegedly
18 * compatible with RSA Labs "RC4" cipher (the actual description of
19 * which is a trade secret). The same algorithm is used as a stream
20 * cipher called "arcfour" in Tatu Ylonen's ssh package.
22 * Here the stream cipher has been modified always to include the time
23 * when initializing the state. That makes it impossible to
24 * regenerate the same random sequence twice, so this can't be used
25 * for encryption, but will generate good random numbers.
27 * RC4 is a registered trademark of RSA Laboratories.
31 #include <libratbox_config.h>
32 #include <ratbox_lib.h>
34 #if !defined(HAVE_OPENSSL) && !defined(HAVE_GNUTLS) && !defined(HAVE_ARC4RANDOM)
36 #include "arc4random.h"
39 #include <sys/resource.h>
51 static int rs_initialized
;
52 static struct arc4_stream rs
;
54 static inline void arc4_init(struct arc4_stream
*);
55 static inline void arc4_addrandom(struct arc4_stream
*, uint8_t *, int);
56 static void arc4_stir(struct arc4_stream
*);
57 static inline uint8_t arc4_getbyte(struct arc4_stream
*);
58 static inline uint32_t arc4_getword(struct arc4_stream
*);
61 arc4_init(struct arc4_stream
*as
)
65 for (n
= 0; n
< 256; n
++)
72 arc4_addrandom(struct arc4_stream
*as
, uint8_t *dat
, int datlen
)
78 for (n
= 0; n
< 256; n
++) {
81 as
->j
= (as
->j
+ si
+ dat
[n
% datlen
]);
82 as
->s
[as
->i
] = as
->s
[as
->j
];
89 arc4_stir(struct arc4_stream
*as
)
94 /* XXX this doesn't support egd sources or similiar */
97 arc4_addrandom(as
, (void *)&pid
, sizeof(pid
));
99 rb_gettimeofday(&tv
, NULL
);
100 arc4_addrandom(as
, (void *)&tv
.tv_sec
, sizeof(&tv
.tv_sec
));
101 arc4_addrandom(as
, (void *)&tv
.tv_usec
, sizeof(&tv
.tv_usec
));
102 rb_gettimeofday(&tv
, NULL
);
103 arc4_addrandom(as
, (void *)&tv
.tv_usec
, sizeof(&tv
.tv_usec
));
105 #if defined(HAVE_GETRUSAGE) && RUSAGE_SELF
108 getrusage(RUSAGE_SELF
, &buf
);
109 arc4_addrandom(as
, (void *)&buf
, sizeof(buf
));
110 memset(&buf
, 0, sizeof(buf
))
118 fd
= open("/dev/urandom", O_RDONLY
);
121 read(fd
, rnd
, sizeof(rnd
));
123 arc4_addrandom(as
, (void *)rnd
, sizeof(rnd
));
128 LARGE_INTEGER performanceCount
;
129 if (QueryPerformanceCounter (&performanceCount
))
131 arc4_addrandom(as
, (void *)&performanceCount
, sizeof(performanceCount
));
138 * Throw away the first N words of output, as suggested in the
139 * paper "Weaknesses in the Key Scheduling Algorithm of RC4"
140 * by Fluher, Mantin, and Shamir.
141 * http://www.wisdom.weizmann.ac.il/~itsik/RC4/Papers/Rc4_ksa.ps
142 * N = 256 in our case.
144 for (n
= 0; n
< 256 * 4; n
++)
148 static inline uint8_t
149 arc4_getbyte(struct arc4_stream
*as
)
155 as
->j
= (as
->j
+ si
);
159 return (as
->s
[(si
+ sj
) & 0xff]);
162 static inline uint32_t
163 arc4_getword(struct arc4_stream
*as
)
166 val
= arc4_getbyte(as
) << 24;
167 val
|= arc4_getbyte(as
) << 16;
168 val
|= arc4_getbyte(as
) << 8;
169 val
|= arc4_getbyte(as
);
174 arc4random_stir(void)
176 if (!rs_initialized
) {
184 arc4random_addrandom(uint8_t *dat
, int datlen
)
188 arc4_addrandom(&rs
, dat
, datlen
);
196 return arc4_getword(&rs
);