2 * THE BEER-WARE LICENSE
4 * <dan@FreeBSD.ORG> wrote this file. As long as you retain this notice you
5 * can do whatever you want with this stuff. If we meet some day, and you
6 * think this stuff is worth it, you can buy me a beer in return.
13 #include <sys/types.h>
14 #include <sys/random.h>
15 #include <sys/libkern.h>
17 #define ARC4_MAXRUNS 64
19 static u_int8_t arc4_i, arc4_j;
20 static int arc4_initialized = 0;
21 static int arc4_numruns = 0;
22 static u_int8_t arc4_sbox[256];
25 arc4_swap(u_int8_t *a, u_int8_t *b)
38 arc4_randomstir (void)
43 /* r = read_random(key, sizeof(key)); */
44 r = 0; /* XXX MarkM - revisit this when /dev/random is done */
45 /* if r == 0 || -1, just use what was on the stack */
48 for (n = r; n < sizeof(key); n++)
52 for (n = 0; n < 256; n++)
54 arc4_j = (arc4_j + arc4_sbox[n] + key[n]) % 256;
55 arc4_swap(&arc4_sbox[n], &arc4_sbox[arc4_j]);
60 * Initialize our S-box to its beginning defaults.
68 for (n = 0; n < 256; n++)
69 arc4_sbox[n] = (u_int8_t) n;
76 * Generate a random byte.
83 arc4_i = (arc4_i + 1) % 256;
84 arc4_j = (arc4_j + arc4_sbox[arc4_i]) % 256;
86 arc4_swap(&arc4_sbox[arc4_i], &arc4_sbox[arc4_j]);
88 arc4_t = (arc4_sbox[arc4_i] + arc4_sbox[arc4_j]) % 256;
89 return arc4_sbox[arc4_t];
97 /* Initialize array if needed. */
98 if (!arc4_initialized)
100 if (++arc4_numruns > ARC4_MAXRUNS)
106 ret = arc4_randbyte();
107 ret |= arc4_randbyte() << 8;
108 ret |= arc4_randbyte() << 16;
109 ret |= arc4_randbyte() << 24;