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Diffstat (limited to 'keyexchange/isakmpd-20041012/sysdep/common/libsysdep/arc4random.c')
| -rw-r--r-- | keyexchange/isakmpd-20041012/sysdep/common/libsysdep/arc4random.c | 178 |
1 files changed, 178 insertions, 0 deletions
diff --git a/keyexchange/isakmpd-20041012/sysdep/common/libsysdep/arc4random.c b/keyexchange/isakmpd-20041012/sysdep/common/libsysdep/arc4random.c new file mode 100644 index 0000000..afd5bb6 --- /dev/null +++ b/keyexchange/isakmpd-20041012/sysdep/common/libsysdep/arc4random.c @@ -0,0 +1,178 @@ +/* $OpenBSD: arc4random.c,v 1.6 2004/10/08 15:18:26 hshoexer Exp $ */ + +/* + * Arc4 random number generator for OpenBSD. + * Copyright 1996 David Mazieres <dm@lcs.mit.edu>. + * + * Modification and redistribution in source and binary forms is + * permitted provided that due credit is given to the author and the + * OpenBSD project by leaving this copyright notice intact. + */ + +/* + * 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 + * which is a trade secret). The same algorithm is used as a stream + * cipher called "arcfour" in Tatu Ylonen's ssh package. + * + * Here the stream cipher has been modified always to include the time + * when initializing the state. That makes it impossible to + * regenerate the same random sequence twice, so this can't be used + * for encryption, but will generate good random numbers. + * + * RC4 is a registered trademark of RSA Laboratories. + */ + +#include <fcntl.h> +#include <stdlib.h> +#include <unistd.h> +#include <sys/types.h> +#include <sys/time.h> + +#ifdef __GNUC__ +#define inline __inline +#else /* !__GNUC__ */ +#define inline +#endif /* !__GNUC__ */ + +struct arc4_stream { + u_int8_t i; + u_int8_t j; + u_int8_t s[256]; +}; + +int rs_initialized; +static struct arc4_stream rs; + +static inline u_int8_t arc4_getbyte(struct arc4_stream *); + +static inline void +arc4_init(struct arc4_stream *as) +{ + int n; + + for (n = 0; n < 256; n++) + as->s[n] = n; + as->i = 0; + as->j = 0; +} + +static inline void +arc4_addrandom(struct arc4_stream *as, u_char *dat, int datlen) +{ + int n; + u_int8_t si; + + as->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; + } + as->j = as->i; +} + +static void +arc4_stir(struct arc4_stream *as) +{ + int fd, i; + struct { + struct timeval tv; + u_int8_t rnd[128 - sizeof(struct timeval)]; + } rdat; + + gettimeofday(&rdat.tv, NULL); + fd = open("/dev/arandom", O_RDONLY); + if (fd < 0) + fd = open("/dev/random", O_RDONLY); + if (fd >= 0) { + read(fd, rdat.rnd, sizeof(rdat.rnd)); + close(fd); + } + /* fd < 0? Ah, what the heck. We'll just take whatever was on the + * stack... */ + + arc4_addrandom(as, (void *)&rdat, sizeof(rdat)); + + /* + * Discard early keystream, as per recommendations in: + * http://www.wisdom.weizmann.ac.il/~itsik/RC4/Papers/Rc4_ksa.ps + */ + for (i = 0; i < 256; i++) + (void)arc4_getbyte(as); +} + +static inline u_int8_t +arc4_getbyte(struct arc4_stream *as) +{ + 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; + return (as->s[(si + sj) & 0xff]); +} + +static inline u_int32_t +arc4_getword(struct arc4_stream *as) +{ + u_int32_t val; + val = arc4_getbyte(as) << 24; + val |= arc4_getbyte(as) << 16; + val |= arc4_getbyte(as) << 8; + val |= arc4_getbyte(as); + return val; +} + +void +arc4random_stir(void) +{ + if (!rs_initialized) { + arc4_init(&rs); + rs_initialized = 1; + } + arc4_stir(&rs); +} + +void +arc4random_addrandom(u_char *dat, int datlen) +{ + if (!rs_initialized) + arc4random_stir(); + arc4_addrandom(&rs, dat, datlen); +} + +u_int32_t +arc4random(void) +{ + if (!rs_initialized) + arc4random_stir(); + return arc4_getword(&rs); +} + +#if 0 +/*-------- Test code for i386 --------*/ +#include <stdio.h> +#include <machine/pctr.h> +int +main(int argc, char **argv) +{ + const int iter = 1000000; + int i; + pctrval v; + + v = rdtsc(); + for (i = 0; i < iter; i++) + arc4random(); + v = rdtsc() - v; + v /= iter; + + printf("%qd cycles\n", v); +} +#endif |