зеркало из https://github.com/github/putty.git
Add the CRC32 compensation attack detector that all other SSH
clients have had for ages and I forgot about. Of course I've got the version with the buffer overflow fixed! [originally from svn r1535]
This commit is contained in:
Simon Tatham
Родитель
349e2ce9e2
Коммит
d237773599
3
LICENCE
3
LICENCE
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@ -1,7 +1,8 @@
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PuTTY is copyright 1997-2001 Simon Tatham.
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Portions copyright Robert de Bath, Joris van Rantwijk, Delian
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Delchev, Andreas Schultz, Jeroen Massar, Wez Furlong, Nicolas Barry.
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Delchev, Andreas Schultz, Jeroen Massar, Wez Furlong, Nicolas Barry,
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and CORE SDI S.A.
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Permission is hereby granted, free of charge, to any person
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obtaining a copy of this software and associated documentation files
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6
Makefile
6
Makefile
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@ -115,9 +115,9 @@ MOBJ2 = tree234.$(OBJ)
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COBJS = console.$(OBJ)
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##-- objects putty pscp psftp plink
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OBJS1 = sshcrc.$(OBJ) sshdes.$(OBJ) sshmd5.$(OBJ) sshrsa.$(OBJ) sshrand.$(OBJ)
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OBJS2 = sshsha.$(OBJ) sshblowf.$(OBJ) noise.$(OBJ) sshdh.$(OBJ) sshdss.$(OBJ)
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OBJS3 = sshbn.$(OBJ) sshpubk.$(OBJ) ssh.$(OBJ) pageantc.$(OBJ) sshzlib.$(OBJ)
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OBJS4 = x11fwd.$(OBJ) portfwd.$(OBJ) sshaes.$(OBJ) sshsh512.$(OBJ)
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OBJS2 = sshsha.$(OBJ) sshblowf.$(OBJ) noise.$(OBJ) sshdh.$(OBJ) sshcrcda.$(OBJ)
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OBJS3 = sshpubk.$(OBJ) ssh.$(OBJ) pageantc.$(OBJ) sshzlib.$(OBJ) sshdss.$(OBJ)
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OBJS4 = x11fwd.$(OBJ) portfwd.$(OBJ) sshaes.$(OBJ) sshsh512.$(OBJ) sshbn.$(OBJ)
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##-- objects pageant
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PAGE1 = pageant.$(OBJ) sshrsa.$(OBJ) sshpubk.$(OBJ) sshdes.$(OBJ) sshbn.$(OBJ)
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PAGE2 = sshmd5.$(OBJ) version.$(OBJ) tree234.$(OBJ) misc.$(OBJ) sshaes.$(OBJ)
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@ -1,11 +1,12 @@
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\versionid $Id: licence.but,v 1.1 2001/12/16 14:56:02 simon Exp $
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\versionid $Id: licence.but,v 1.2 2002/01/08 11:57:32 simon Exp $
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\A{licence} PuTTY Licence
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PuTTY is copyright 1997-2001 Simon Tatham.
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Portions copyright Robert de Bath, Joris van Rantwijk, Delian
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Delchev, Andreas Schultz, Jeroen Massar, Wez Furlong, Nicolas Barry.
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Delchev, Andreas Schultz, Jeroen Massar, Wez Furlong, Nicolas Barry,
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and CORE SDI S.A.
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Permission is hereby granted, free of charge, to any person
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obtaining a copy of this software and associated documentation files
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@ -66,7 +66,7 @@ BEGIN
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LTEXT "Portions copyright Robert de Bath, Joris van Rantwijk, Delian", 1001, 10, 26, 206, 8
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LTEXT "Delchev, Andreas Schultz, Jeroen Massar, Wez Furlong, Nicolas", 1002, 10, 34, 206, 8
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LTEXT "Barry.", 1003, 10, 42, 206, 8
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LTEXT "Barry, and CORE SDI S.A.", 1003, 10, 42, 206, 8
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LTEXT "Permission is hereby granted, free of charge, to any person", 1004, 10, 58, 206, 8
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LTEXT "obtaining a copy of this software and associated documentation", 1005, 10, 66, 206, 8
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@ -59,7 +59,7 @@ BEGIN
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LTEXT "Portions copyright Robert de Bath, Joris van Rantwijk, Delian", 1001, 10, 26, 206, 8
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LTEXT "Delchev, Andreas Schultz, Jeroen Massar, Wez Furlong, Nicolas", 1002, 10, 34, 206, 8
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LTEXT "Barry.", 1003, 10, 42, 206, 8
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LTEXT "Barry, and CORE SDI S.A.", 1003, 10, 42, 206, 8
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LTEXT "Permission is hereby granted, free of charge, to any person", 1004, 10, 58, 206, 8
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LTEXT "obtaining a copy of this software and associated documentation", 1005, 10, 66, 206, 8
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5
ssh.c
5
ssh.c
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@ -724,6 +724,11 @@ static int ssh1_rdpkt(unsigned char **data, int *datalen)
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st->to_read -= st->chunk;
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}
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if (cipher && detect_attack(pktin.data, st->biglen, NULL)) {
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bombout(("Network attack (CRC compensation) detected!"));
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crReturn(0);
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}
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if (cipher)
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cipher->decrypt(pktin.data, st->biglen);
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4
ssh.h
4
ssh.h
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@ -72,6 +72,10 @@ typedef unsigned int word32;
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typedef unsigned int uint32;
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unsigned long crc32(const void *s, size_t len);
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unsigned long crc32_update(unsigned long crc_input, const void *s, size_t len);
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/* SSH CRC compensation attack detector */
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int detect_attack(unsigned char *buf, uint32 len, unsigned char *IV);
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typedef struct {
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uint32 h[4];
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8
sshcrc.c
8
sshcrc.c
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@ -211,9 +211,8 @@ int main(void)
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}
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#endif
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unsigned long crc32(const void *buf, size_t len)
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unsigned long crc32_update(unsigned long crcword, const void *buf, size_t len)
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{
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unsigned long crcword = 0L;
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const unsigned char *p = (const unsigned char *) buf;
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while (len--) {
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unsigned long newbyte = *p++;
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@ -222,3 +221,8 @@ unsigned long crc32(const void *buf, size_t len)
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}
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return crcword;
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}
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unsigned long crc32(const void *buf, size_t len)
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{
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return crc32_update(0L, buf, len);
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}
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@ -0,0 +1,157 @@
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/* $OpenBSD: deattack.c,v 1.14 2001/06/23 15:12:18 itojun Exp $ */
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/*
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* Cryptographic attack detector for ssh - source code
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*
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* Copyright (c) 1998 CORE SDI S.A., Buenos Aires, Argentina.
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*
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* All rights reserved. Redistribution and use in source and binary
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* forms, with or without modification, are permitted provided that
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* this copyright notice is retained.
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*
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* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
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* WARRANTIES ARE DISCLAIMED. IN NO EVENT SHALL CORE SDI S.A. BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY OR
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* CONSEQUENTIAL DAMAGES RESULTING FROM THE USE OR MISUSE OF THIS
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* SOFTWARE.
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*
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* Ariel Futoransky <futo@core-sdi.com>
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* <http://www.core-sdi.com>
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*
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* Modified for use in PuTTY by Simon Tatham
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*/
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#include <assert.h>
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#include "misc.h"
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#include "ssh.h"
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typedef unsigned char uchar;
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typedef unsigned short uint16;
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/* SSH Constants */
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#define SSH_MAXBLOCKS (32 * 1024)
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#define SSH_BLOCKSIZE (8)
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/* Hashing constants */
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#define HASH_MINSIZE (8 * 1024)
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#define HASH_ENTRYSIZE (sizeof(uint16))
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#define HASH_FACTOR(x) ((x)*3/2)
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#define HASH_UNUSEDCHAR (0xff)
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#define HASH_UNUSED (0xffff)
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#define HASH_IV (0xfffe)
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#define HASH_MINBLOCKS (7*SSH_BLOCKSIZE)
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#define GET_32BIT_MSB_FIRST(cp) \
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(((unsigned long)(unsigned char)(cp)[0] << 24) | \
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((unsigned long)(unsigned char)(cp)[1] << 16) | \
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((unsigned long)(unsigned char)(cp)[2] << 8) | \
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((unsigned long)(unsigned char)(cp)[3]))
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/* Hash function (Input keys are cipher results) */
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#define HASH(x) GET_32BIT_MSB_FIRST(x)
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#define CMP(a, b) (memcmp(a, b, SSH_BLOCKSIZE))
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uchar ONE[4] = { 1, 0, 0, 0 };
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uchar ZERO[4] = { 0, 0, 0, 0 };
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static void crc_update(uint32 *a, void *b)
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{
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*a = crc32_update(*a, b, 4);
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}
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/* detect if a block is used in a particular pattern */
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static int check_crc(uchar *S, uchar *buf, uint32 len, uchar *IV)
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{
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uint32 crc;
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uchar *c;
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crc = 0;
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if (IV && !CMP(S, IV)) {
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crc_update(&crc, ONE);
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crc_update(&crc, ZERO);
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}
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for (c = buf; c < buf + len; c += SSH_BLOCKSIZE) {
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if (!CMP(S, c)) {
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crc_update(&crc, ONE);
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crc_update(&crc, ZERO);
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} else {
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crc_update(&crc, ZERO);
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crc_update(&crc, ZERO);
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}
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}
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return (crc == 0);
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}
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/* Detect a crc32 compensation attack on a packet */
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int detect_attack(uchar *buf, uint32 len, uchar *IV)
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{
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static uint16 *h = (uint16 *) NULL;
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static uint32 n = HASH_MINSIZE / HASH_ENTRYSIZE;
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register uint32 i, j;
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uint32 l;
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register uchar *c;
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uchar *d;
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assert(!(len > (SSH_MAXBLOCKS * SSH_BLOCKSIZE) ||
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len % SSH_BLOCKSIZE != 0));
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for (l = n; l < HASH_FACTOR(len / SSH_BLOCKSIZE); l = l << 2)
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;
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if (h == NULL) {
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logevent("Installing CRC compensation attack detector");
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n = l;
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h = (uint16 *) smalloc(n * HASH_ENTRYSIZE);
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} else {
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if (l > n) {
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n = l;
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h = (uint16 *) srealloc(h, n * HASH_ENTRYSIZE);
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}
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}
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if (len <= HASH_MINBLOCKS) {
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for (c = buf; c < buf + len; c += SSH_BLOCKSIZE) {
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if (IV && (!CMP(c, IV))) {
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if ((check_crc(c, buf, len, IV)))
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return 1; /* attack detected */
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else
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break;
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}
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for (d = buf; d < c; d += SSH_BLOCKSIZE) {
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if (!CMP(c, d)) {
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if ((check_crc(c, buf, len, IV)))
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return 1; /* attack detected */
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else
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break;
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}
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}
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}
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return 0; /* ok */
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}
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memset(h, HASH_UNUSEDCHAR, n * HASH_ENTRYSIZE);
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if (IV)
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h[HASH(IV) & (n - 1)] = HASH_IV;
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for (c = buf, j = 0; c < (buf + len); c += SSH_BLOCKSIZE, j++) {
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for (i = HASH(c) & (n - 1); h[i] != HASH_UNUSED;
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i = (i + 1) & (n - 1)) {
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if (h[i] == HASH_IV) {
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if (!CMP(c, IV)) {
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if (check_crc(c, buf, len, IV))
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return 1; /* attack detected */
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else
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break;
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}
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} else if (!CMP(c, buf + h[i] * SSH_BLOCKSIZE)) {
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if (check_crc(c, buf, len, IV))
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return 1; /* attack detected */
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else
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break;
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}
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}
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h[i] = j;
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}
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return 0; /* ok */
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}
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@ -87,7 +87,7 @@ BEGIN
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LTEXT "Portions copyright Robert de Bath, Joris van Rantwijk, Delian", 1001, 10, 26, 206, 8
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LTEXT "Delchev, Andreas Schultz, Jeroen Massar, Wez Furlong, Nicolas", 1002, 10, 34, 206, 8
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LTEXT "Barry.", 1003, 10, 42, 206, 8
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LTEXT "Barry, and CORE SDI S.A.", 1003, 10, 42, 206, 8
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LTEXT "Permission is hereby granted, free of charge, to any person", 1004, 10, 58, 206, 8
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LTEXT "obtaining a copy of this software and associated documentation", 1005, 10, 66, 206, 8
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