removed prng.c from libfreeswan
This commit is contained in:
Andreas Steffen
parent
e92e687584
commit
5922c484f6
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@ -3,7 +3,7 @@ libfreeswan_a_SOURCES = addrtoa.c addrtot.c addrtypeof.c anyaddr.c atoaddr.c ato
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atosa.c atosubnet.c atoul.c copyright.c datatot.c freeswan.h \
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goodmask.c initaddr.c initsaid.c initsubnet.c internal.h ipsec_param.h \
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keyblobtoid.c pfkey_v2_build.c pfkey_v2_debug.c \
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pfkey_v2_ext_bits.c pfkey_v2_parse.c portof.c prng.c rangetoa.c \
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pfkey_v2_ext_bits.c pfkey_v2_parse.c portof.c rangetoa.c \
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pfkey.h pfkeyv2.h rangetosubnet.c sameaddr.c satoa.c \
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satot.c subnetof.c subnettoa.c subnettot.c \
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subnettypeof.c ttoaddr.c ttodata.c ttoprotoport.c ttosa.c ttosubnet.c ttoul.c \
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@ -15,6 +15,6 @@ INCLUDES = \
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-I$(top_srcdir)/src/pluto
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dist_man3_MANS = anyaddr.3 atoaddr.3 atoasr.3 atosa.3 atoul.3 goodmask.3 initaddr.3 initsubnet.3 \
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keyblobtoid.3 portof.3 prng.3 rangetosubnet.3 sameaddr.3 subnetof.3 \
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keyblobtoid.3 portof.3 rangetosubnet.3 sameaddr.3 subnetof.3 \
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ttoaddr.3 ttodata.3 ttosa.3 ttoul.3
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@ -206,12 +206,6 @@ void setportof(int port, ip_address *dst);
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struct sockaddr *sockaddrof(ip_address *src);
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size_t sockaddrlenof(const ip_address *src);
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/* PRNG */
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void prng_init(struct prng *prng, const unsigned char *key, size_t keylen);
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void prng_bytes(struct prng *prng, unsigned char *dst, size_t dstlen);
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unsigned long prng_count(struct prng *prng);
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void prng_final(struct prng *prng);
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/* odds and ends */
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const char **ipsec_copyright_notice(void);
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@ -1,120 +0,0 @@
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.TH IPSEC_PRNG 3 "1 April 2002"
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.SH NAME
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ipsec prng_init \- initialize IPsec pseudorandom-number generator
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.br
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ipsec prng_bytes \- get bytes from IPsec pseudorandom-number generator
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.br
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ipsec prng_final \- close down IPsec pseudorandom-number generator
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.SH SYNOPSIS
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.B "#include <freeswan.h>
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.sp
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.B "void prng_init(struct prng *prng,"
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.ti +1c
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.B "const unsigned char *key, size_t keylen);"
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.br
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.B "void prng_bytes(struct prng *prng, char *dst,"
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.ti +1c
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.B "size_t dstlen);"
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.br
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.B "unsigned long prng_count(struct prng *prng);"
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.br
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.B "void prng_final(struct prng *prng);"
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.SH DESCRIPTION
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.I Prng_init
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initializes a crypto-quality pseudo-random-number generator from a key;
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.I prng_bytes
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obtains pseudo-random bytes from it;
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.I prng_count
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reports the number of bytes extracted from it to date;
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.I prng_final
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closes it down.
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It is the user's responsibility to initialize a PRNG before using it,
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and not to use it again after it is closed down.
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.PP
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.I Prng_init
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initializes,
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or re-initializes,
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the specified
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.I prng
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from the
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.IR key ,
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whose length is given by
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.IR keylen .
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The user must allocate the
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.B "struct prng"
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pointed to by
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.IR prng .
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There is no particular constraint on the length of the key,
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although a key longer than 256 bytes is unnecessary because
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only the first 256 would be used.
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Initialization requires on the order of 3000 integer operations,
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independent of key length.
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.PP
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.I Prng_bytes
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obtains
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.I dstlen
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pseudo-random bytes from the PRNG and puts them in
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.IR buf .
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This is quite fast,
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on the order of 10 integer operations per byte.
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.PP
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.I Prng_count
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reports the number of bytes obtained from the PRNG
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since it was (last) initialized.
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.PP
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.I Prng_final
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closes down a PRNG by
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zeroing its internal memory,
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obliterating all trace of the state used to generate its previous output.
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This requires on the order of 250 integer operations.
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.PP
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The
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.B <freeswan.h>
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header file supplies the definition of the
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.B prng
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structure.
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Examination of its innards is discouraged, as they may change.
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.PP
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The PRNG algorithm
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used by these functions is currently identical to that of RC4(TM).
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This algorithm is cryptographically strong,
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sufficiently unpredictable that even a hostile observer will
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have difficulty determining the next byte of output from past history,
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provided it is initialized from a reasonably large key composed of
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highly random bytes (see
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.IR random (4)).
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The usual run of software pseudo-random-number generators
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(e.g.
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.IR random (3))
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are
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.I not
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cryptographically strong.
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.PP
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The well-known attacks against RC4(TM),
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e.g. as found in 802.11b's WEP encryption system,
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apply only if multiple PRNGs are initialized with closely-related keys
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(e.g., using a counter appended to a base key).
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If such keys are used, the first few hundred pseudo-random bytes
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from each PRNG should be discarded,
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to give the PRNGs a chance to randomize their innards properly.
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No useful attacks are known if the key is well randomized to begin with.
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.SH SEE ALSO
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random(3), random(4)
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.br
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Bruce Schneier,
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\fIApplied Cryptography\fR, 2nd ed., 1996, ISBN 0-471-11709-9,
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pp. 397-8.
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.SH HISTORY
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Written for the FreeS/WAN project by Henry Spencer.
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.SH BUGS
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If an attempt is made to obtain more than 4e9 bytes
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between initializations,
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the PRNG will continue to work but
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.IR prng_count 's
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output will stick at
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.BR 4000000000 .
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Fixing this would require a longer integer type and does
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not seem worth the trouble,
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since you should probably re-initialize before then anyway...
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.PP
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``RC4'' is a trademark of RSA Data Security, Inc.
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@ -1,200 +0,0 @@
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/*
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* crypto-class pseudorandom number generator
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* currently uses same algorithm as RC4(TM), from Schneier 2nd ed p397
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* Copyright (C) 2002 Henry Spencer.
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*
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* This library is free software; you can redistribute it and/or modify it
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* under the terms of the GNU Library General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or (at your
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* option) any later version. See <http://www.fsf.org/copyleft/lgpl.txt>.
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*
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* This library is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public
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* License for more details.
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*/
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#include "internal.h"
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#include "freeswan.h"
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/*
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- prng_init - initialize PRNG from a key
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*/
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void
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prng_init(prng, key, keylen)
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struct prng *prng;
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const unsigned char *key;
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size_t keylen;
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{
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unsigned char k[256];
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int i, j;
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unsigned const char *p;
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unsigned const char *keyend = key + keylen;
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unsigned char t;
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for (i = 0; i <= 255; i++)
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prng->sbox[i] = i;
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p = key;
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for (i = 0; i <= 255; i++) {
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k[i] = *p++;
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if (p >= keyend)
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p = key;
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}
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j = 0;
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for (i = 0; i <= 255; i++) {
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j = (j + prng->sbox[i] + k[i]) & 0xff;
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t = prng->sbox[i];
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prng->sbox[i] = prng->sbox[j];
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prng->sbox[j] = t;
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k[i] = 0; /* clear out key memory */
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}
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prng->i = 0;
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prng->j = 0;
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prng->count = 0;
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}
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/*
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- prng_bytes - get some pseudorandom bytes from PRNG
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*/
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void
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prng_bytes(prng, dst, dstlen)
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struct prng *prng;
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unsigned char *dst;
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size_t dstlen;
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{
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int i, j, t;
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unsigned char *p = dst;
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size_t remain = dstlen;
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# define MAX 4000000000ul
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while (remain > 0) {
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i = (prng->i + 1) & 0xff;
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prng->i = i;
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j = (prng->j + prng->sbox[i]) & 0xff;
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prng->j = j;
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t = prng->sbox[i];
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prng->sbox[i] = prng->sbox[j];
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prng->sbox[j] = t;
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t = (t + prng->sbox[i]) & 0xff;
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*p++ = prng->sbox[t];
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remain--;
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}
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if (prng->count < MAX - dstlen)
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prng->count += dstlen;
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else
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prng->count = MAX;
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}
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/*
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- prnt_count - how many bytes have been extracted from PRNG so far?
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*/
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unsigned long
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prng_count(prng)
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struct prng *prng;
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{
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return prng->count;
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}
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/*
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- prng_final - clear out PRNG to ensure nothing left in memory
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*/
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void
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prng_final(prng)
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struct prng *prng;
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{
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int i;
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for (i = 0; i <= 255; i++)
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prng->sbox[i] = 0;
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prng->i = 0;
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prng->j = 0;
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prng->count = 0; /* just for good measure */
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}
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#ifdef PRNG_MAIN
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#include <stdio.h>
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void regress();
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int
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main(argc, argv)
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int argc;
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char *argv[];
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{
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struct prng pr;
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unsigned char buf[100];
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unsigned char *p;
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size_t n;
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if (argc < 2) {
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fprintf(stderr, "Usage: %s {key|-r}\n", argv[0]);
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exit(2);
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}
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if (strcmp(argv[1], "-r") == 0) {
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regress();
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fprintf(stderr, "regress() returned?!?\n");
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exit(1);
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}
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prng_init(&pr, argv[1], strlen(argv[1]));
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prng_bytes(&pr, buf, 32);
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printf("0x");
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for (p = buf, n = 32; n > 0; p++, n--)
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printf("%02x", *p);
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printf("\n%lu bytes\n", prng_count(&pr));
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prng_final(&pr);
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exit(0);
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}
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void
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regress()
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{
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struct prng pr;
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unsigned char buf[100];
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unsigned char *p;
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size_t n;
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/* somewhat non-random sample key */
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unsigned char key[] = "here we go gathering nuts in May";
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/* first thirty bytes of output from that key */
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unsigned char good[] = "\x3f\x02\x8e\x4a\x2a\xea\x23\x18\x92\x7c"
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"\x09\x52\x83\x61\xaa\x26\xce\xbb\x9d\x71"
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"\x71\xe5\x10\x22\xaf\x60\x54\x8d\x5b\x28";
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int nzero, none;
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int show = 0;
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prng_init(&pr, key, strlen(key));
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prng_bytes(&pr, buf, sizeof(buf));
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for (p = buf, n = sizeof(buf); n > 0; p++, n--) {
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if (*p == 0)
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nzero++;
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if (*p == 255)
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none++;
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}
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if (nzero > 3 || none > 3) {
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fprintf(stderr, "suspiciously non-random output!\n");
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show = 1;
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}
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if (memcmp(buf, good, strlen(good)) != 0) {
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fprintf(stderr, "incorrect output!\n");
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show = 1;
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}
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if (show) {
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fprintf(stderr, "0x");
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for (p = buf, n = sizeof(buf); n > 0; p++, n--)
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fprintf(stderr, "%02x", *p);
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fprintf(stderr, "\n");
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exit(1);
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}
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if (prng_count(&pr) != sizeof(buf)) {
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fprintf(stderr, "got %u bytes, but count is %lu\n",
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sizeof(buf), prng_count(&pr));
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exit(1);
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}
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prng_final(&pr);
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exit(0);
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}
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#endif /* PRNG_MAIN */
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