diff options
Diffstat (limited to 'src')
-rw-r--r-- | src/libfreeswan/Makefile.am | 4 | ||||
-rw-r--r-- | src/libfreeswan/freeswan.h | 6 | ||||
-rw-r--r-- | src/libfreeswan/prng.3 | 120 | ||||
-rw-r--r-- | src/libfreeswan/prng.c | 200 |
4 files changed, 2 insertions, 328 deletions
diff --git a/src/libfreeswan/Makefile.am b/src/libfreeswan/Makefile.am index 5fee39da9..554bc8a03 100644 --- a/src/libfreeswan/Makefile.am +++ b/src/libfreeswan/Makefile.am @@ -3,7 +3,7 @@ libfreeswan_a_SOURCES = addrtoa.c addrtot.c addrtypeof.c anyaddr.c atoaddr.c ato atosa.c atosubnet.c atoul.c copyright.c datatot.c freeswan.h \ goodmask.c initaddr.c initsaid.c initsubnet.c internal.h ipsec_param.h \ keyblobtoid.c pfkey_v2_build.c pfkey_v2_debug.c \ - pfkey_v2_ext_bits.c pfkey_v2_parse.c portof.c prng.c rangetoa.c \ + pfkey_v2_ext_bits.c pfkey_v2_parse.c portof.c rangetoa.c \ pfkey.h pfkeyv2.h rangetosubnet.c sameaddr.c satoa.c \ satot.c subnetof.c subnettoa.c subnettot.c \ subnettypeof.c ttoaddr.c ttodata.c ttoprotoport.c ttosa.c ttosubnet.c ttoul.c \ @@ -15,6 +15,6 @@ INCLUDES = \ -I$(top_srcdir)/src/pluto dist_man3_MANS = anyaddr.3 atoaddr.3 atoasr.3 atosa.3 atoul.3 goodmask.3 initaddr.3 initsubnet.3 \ - keyblobtoid.3 portof.3 prng.3 rangetosubnet.3 sameaddr.3 subnetof.3 \ + keyblobtoid.3 portof.3 rangetosubnet.3 sameaddr.3 subnetof.3 \ ttoaddr.3 ttodata.3 ttosa.3 ttoul.3 diff --git a/src/libfreeswan/freeswan.h b/src/libfreeswan/freeswan.h index 342f59987..d931355a3 100644 --- a/src/libfreeswan/freeswan.h +++ b/src/libfreeswan/freeswan.h @@ -206,12 +206,6 @@ void setportof(int port, ip_address *dst); struct sockaddr *sockaddrof(ip_address *src); size_t sockaddrlenof(const ip_address *src); -/* PRNG */ -void prng_init(struct prng *prng, const unsigned char *key, size_t keylen); -void prng_bytes(struct prng *prng, unsigned char *dst, size_t dstlen); -unsigned long prng_count(struct prng *prng); -void prng_final(struct prng *prng); - /* odds and ends */ const char **ipsec_copyright_notice(void); diff --git a/src/libfreeswan/prng.3 b/src/libfreeswan/prng.3 deleted file mode 100644 index 48c6ceed0..000000000 --- a/src/libfreeswan/prng.3 +++ /dev/null @@ -1,120 +0,0 @@ -.TH IPSEC_PRNG 3 "1 April 2002" -.SH NAME -ipsec prng_init \- initialize IPsec pseudorandom-number generator -.br -ipsec prng_bytes \- get bytes from IPsec pseudorandom-number generator -.br -ipsec prng_final \- close down IPsec pseudorandom-number generator -.SH SYNOPSIS -.B "#include <freeswan.h> -.sp -.B "void prng_init(struct prng *prng," -.ti +1c -.B "const unsigned char *key, size_t keylen);" -.br -.B "void prng_bytes(struct prng *prng, char *dst," -.ti +1c -.B "size_t dstlen);" -.br -.B "unsigned long prng_count(struct prng *prng);" -.br -.B "void prng_final(struct prng *prng);" -.SH DESCRIPTION -.I Prng_init -initializes a crypto-quality pseudo-random-number generator from a key; -.I prng_bytes -obtains pseudo-random bytes from it; -.I prng_count -reports the number of bytes extracted from it to date; -.I prng_final -closes it down. -It is the user's responsibility to initialize a PRNG before using it, -and not to use it again after it is closed down. -.PP -.I Prng_init -initializes, -or re-initializes, -the specified -.I prng -from the -.IR key , -whose length is given by -.IR keylen . -The user must allocate the -.B "struct prng" -pointed to by -.IR prng . -There is no particular constraint on the length of the key, -although a key longer than 256 bytes is unnecessary because -only the first 256 would be used. -Initialization requires on the order of 3000 integer operations, -independent of key length. -.PP -.I Prng_bytes -obtains -.I dstlen -pseudo-random bytes from the PRNG and puts them in -.IR buf . -This is quite fast, -on the order of 10 integer operations per byte. -.PP -.I Prng_count -reports the number of bytes obtained from the PRNG -since it was (last) initialized. -.PP -.I Prng_final -closes down a PRNG by -zeroing its internal memory, -obliterating all trace of the state used to generate its previous output. -This requires on the order of 250 integer operations. -.PP -The -.B <freeswan.h> -header file supplies the definition of the -.B prng -structure. -Examination of its innards is discouraged, as they may change. -.PP -The PRNG algorithm -used by these functions is currently identical to that of RC4(TM). -This algorithm is cryptographically strong, -sufficiently unpredictable that even a hostile observer will -have difficulty determining the next byte of output from past history, -provided it is initialized from a reasonably large key composed of -highly random bytes (see -.IR random (4)). -The usual run of software pseudo-random-number generators -(e.g. -.IR random (3)) -are -.I not -cryptographically strong. -.PP -The well-known attacks against RC4(TM), -e.g. as found in 802.11b's WEP encryption system, -apply only if multiple PRNGs are initialized with closely-related keys -(e.g., using a counter appended to a base key). -If such keys are used, the first few hundred pseudo-random bytes -from each PRNG should be discarded, -to give the PRNGs a chance to randomize their innards properly. -No useful attacks are known if the key is well randomized to begin with. -.SH SEE ALSO -random(3), random(4) -.br -Bruce Schneier, -\fIApplied Cryptography\fR, 2nd ed., 1996, ISBN 0-471-11709-9, -pp. 397-8. -.SH HISTORY -Written for the FreeS/WAN project by Henry Spencer. -.SH BUGS -If an attempt is made to obtain more than 4e9 bytes -between initializations, -the PRNG will continue to work but -.IR prng_count 's -output will stick at -.BR 4000000000 . -Fixing this would require a longer integer type and does -not seem worth the trouble, -since you should probably re-initialize before then anyway... -.PP -``RC4'' is a trademark of RSA Data Security, Inc. diff --git a/src/libfreeswan/prng.c b/src/libfreeswan/prng.c deleted file mode 100644 index 347f13f89..000000000 --- a/src/libfreeswan/prng.c +++ /dev/null @@ -1,200 +0,0 @@ -/* - * crypto-class pseudorandom number generator - * currently uses same algorithm as RC4(TM), from Schneier 2nd ed p397 - * Copyright (C) 2002 Henry Spencer. - * - * This library is free software; you can redistribute it and/or modify it - * under the terms of the GNU Library General Public License as published by - * the Free Software Foundation; either version 2 of the License, or (at your - * option) any later version. See <http://www.fsf.org/copyleft/lgpl.txt>. - * - * This library is distributed in the hope that it will be useful, but - * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY - * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public - * License for more details. - */ -#include "internal.h" -#include "freeswan.h" - -/* - - prng_init - initialize PRNG from a key - */ -void -prng_init(prng, key, keylen) -struct prng *prng; -const unsigned char *key; -size_t keylen; -{ - unsigned char k[256]; - int i, j; - unsigned const char *p; - unsigned const char *keyend = key + keylen; - unsigned char t; - - for (i = 0; i <= 255; i++) - prng->sbox[i] = i; - p = key; - for (i = 0; i <= 255; i++) { - k[i] = *p++; - if (p >= keyend) - p = key; - } - j = 0; - for (i = 0; i <= 255; i++) { - j = (j + prng->sbox[i] + k[i]) & 0xff; - t = prng->sbox[i]; - prng->sbox[i] = prng->sbox[j]; - prng->sbox[j] = t; - k[i] = 0; /* clear out key memory */ - } - prng->i = 0; - prng->j = 0; - prng->count = 0; -} - -/* - - prng_bytes - get some pseudorandom bytes from PRNG - */ -void -prng_bytes(prng, dst, dstlen) -struct prng *prng; -unsigned char *dst; -size_t dstlen; -{ - int i, j, t; - unsigned char *p = dst; - size_t remain = dstlen; -# define MAX 4000000000ul - - while (remain > 0) { - i = (prng->i + 1) & 0xff; - prng->i = i; - j = (prng->j + prng->sbox[i]) & 0xff; - prng->j = j; - t = prng->sbox[i]; - prng->sbox[i] = prng->sbox[j]; - prng->sbox[j] = t; - t = (t + prng->sbox[i]) & 0xff; - *p++ = prng->sbox[t]; - remain--; - } - if (prng->count < MAX - dstlen) - prng->count += dstlen; - else - prng->count = MAX; -} - -/* - - prnt_count - how many bytes have been extracted from PRNG so far? - */ -unsigned long -prng_count(prng) -struct prng *prng; -{ - return prng->count; -} - -/* - - prng_final - clear out PRNG to ensure nothing left in memory - */ -void -prng_final(prng) -struct prng *prng; -{ - int i; - - for (i = 0; i <= 255; i++) - prng->sbox[i] = 0; - prng->i = 0; - prng->j = 0; - prng->count = 0; /* just for good measure */ -} - - - -#ifdef PRNG_MAIN - -#include <stdio.h> - -void regress(); - -int -main(argc, argv) -int argc; -char *argv[]; -{ - struct prng pr; - unsigned char buf[100]; - unsigned char *p; - size_t n; - - if (argc < 2) { - fprintf(stderr, "Usage: %s {key|-r}\n", argv[0]); - exit(2); - } - - if (strcmp(argv[1], "-r") == 0) { - regress(); - fprintf(stderr, "regress() returned?!?\n"); - exit(1); - } - - prng_init(&pr, argv[1], strlen(argv[1])); - prng_bytes(&pr, buf, 32); - printf("0x"); - for (p = buf, n = 32; n > 0; p++, n--) - printf("%02x", *p); - printf("\n%lu bytes\n", prng_count(&pr)); - prng_final(&pr); - exit(0); -} - -void -regress() -{ - struct prng pr; - unsigned char buf[100]; - unsigned char *p; - size_t n; - /* somewhat non-random sample key */ - unsigned char key[] = "here we go gathering nuts in May"; - /* first thirty bytes of output from that key */ - unsigned char good[] = "\x3f\x02\x8e\x4a\x2a\xea\x23\x18\x92\x7c" - "\x09\x52\x83\x61\xaa\x26\xce\xbb\x9d\x71" - "\x71\xe5\x10\x22\xaf\x60\x54\x8d\x5b\x28"; - int nzero, none; - int show = 0; - - prng_init(&pr, key, strlen(key)); - prng_bytes(&pr, buf, sizeof(buf)); - for (p = buf, n = sizeof(buf); n > 0; p++, n--) { - if (*p == 0) - nzero++; - if (*p == 255) - none++; - } - if (nzero > 3 || none > 3) { - fprintf(stderr, "suspiciously non-random output!\n"); - show = 1; - } - if (memcmp(buf, good, strlen(good)) != 0) { - fprintf(stderr, "incorrect output!\n"); - show = 1; - } - if (show) { - fprintf(stderr, "0x"); - for (p = buf, n = sizeof(buf); n > 0; p++, n--) - fprintf(stderr, "%02x", *p); - fprintf(stderr, "\n"); - exit(1); - } - if (prng_count(&pr) != sizeof(buf)) { - fprintf(stderr, "got %u bytes, but count is %lu\n", - sizeof(buf), prng_count(&pr)); - exit(1); - } - prng_final(&pr); - exit(0); -} - -#endif /* PRNG_MAIN */ |