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deattack.c (69587) deattack.c (76259)
1/* $OpenBSD: deattack.c,v 1.10 2000/10/31 13:18:53 markus Exp $ */
1/* $OpenBSD: deattack.c,v 1.13 2001/03/01 02:45:10 deraadt Exp $ */
2
3/*
4 * Cryptographic attack detector for ssh - source code
5 *
6 * Copyright (c) 1998 CORE SDI S.A., Buenos Aires, Argentina.
7 *
8 * All rights reserved. Redistribution and use in source and binary
9 * forms, with or without modification, are permitted provided that

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16 * SOFTWARE.
17 *
18 * Ariel Futoransky <futo@core-sdi.com>
19 * <http://www.core-sdi.com>
20 */
21
22#include "includes.h"
23#include "deattack.h"
2
3/*
4 * Cryptographic attack detector for ssh - source code
5 *
6 * Copyright (c) 1998 CORE SDI S.A., Buenos Aires, Argentina.
7 *
8 * All rights reserved. Redistribution and use in source and binary
9 * forms, with or without modification, are permitted provided that

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16 * SOFTWARE.
17 *
18 * Ariel Futoransky <futo@core-sdi.com>
19 * <http://www.core-sdi.com>
20 */
21
22#include "includes.h"
23#include "deattack.h"
24#include "ssh.h"
24#include "log.h"
25#include "crc32.h"
26#include "getput.h"
27#include "xmalloc.h"
28
29/* SSH Constants */
30#define SSH_MAXBLOCKS (32 * 1024)
31#define SSH_BLOCKSIZE (8)
32

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39#define HASH_IV (0xfffe)
40
41#define HASH_MINBLOCKS (7*SSH_BLOCKSIZE)
42
43
44/* Hash function (Input keys are cipher results) */
45#define HASH(x) GET_32BIT(x)
46
25#include "crc32.h"
26#include "getput.h"
27#include "xmalloc.h"
28
29/* SSH Constants */
30#define SSH_MAXBLOCKS (32 * 1024)
31#define SSH_BLOCKSIZE (8)
32

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39#define HASH_IV (0xfffe)
40
41#define HASH_MINBLOCKS (7*SSH_BLOCKSIZE)
42
43
44/* Hash function (Input keys are cipher results) */
45#define HASH(x) GET_32BIT(x)
46
47#define CMP(a,b) (memcmp(a, b, SSH_BLOCKSIZE))
47#define CMP(a, b) (memcmp(a, b, SSH_BLOCKSIZE))
48
49
50void
51crc_update(u_int32_t *a, u_int32_t b)
52{
53 b ^= *a;
48
49
50void
51crc_update(u_int32_t *a, u_int32_t b)
52{
53 b ^= *a;
54 *a = ssh_crc32((unsigned char *) &b, sizeof(b));
54 *a = ssh_crc32((u_char *) &b, sizeof(b));
55}
56
57/* detect if a block is used in a particular pattern */
58int
55}
56
57/* detect if a block is used in a particular pattern */
58int
59check_crc(unsigned char *S, unsigned char *buf, u_int32_t len,
60 unsigned char *IV)
59check_crc(u_char *S, u_char *buf, u_int32_t len,
60 u_char *IV)
61{
62 u_int32_t crc;
61{
62 u_int32_t crc;
63 unsigned char *c;
63 u_char *c;
64
65 crc = 0;
66 if (IV && !CMP(S, IV)) {
67 crc_update(&crc, 1);
68 crc_update(&crc, 0);
69 }
70 for (c = buf; c < buf + len; c += SSH_BLOCKSIZE) {
71 if (!CMP(S, c)) {

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77 }
78 }
79 return (crc == 0);
80}
81
82
83/* Detect a crc32 compensation attack on a packet */
84int
64
65 crc = 0;
66 if (IV && !CMP(S, IV)) {
67 crc_update(&crc, 1);
68 crc_update(&crc, 0);
69 }
70 for (c = buf; c < buf + len; c += SSH_BLOCKSIZE) {
71 if (!CMP(S, c)) {

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77 }
78 }
79 return (crc == 0);
80}
81
82
83/* Detect a crc32 compensation attack on a packet */
84int
85detect_attack(unsigned char *buf, u_int32_t len, unsigned char *IV)
85detect_attack(u_char *buf, u_int32_t len, u_char *IV)
86{
87 static u_int16_t *h = (u_int16_t *) NULL;
88 static u_int32_t n = HASH_MINSIZE / HASH_ENTRYSIZE;
89 register u_int32_t i, j;
90 u_int32_t l;
86{
87 static u_int16_t *h = (u_int16_t *) NULL;
88 static u_int32_t n = HASH_MINSIZE / HASH_ENTRYSIZE;
89 register u_int32_t i, j;
90 u_int32_t l;
91 register unsigned char *c;
92 unsigned char *d;
91 register u_char *c;
92 u_char *d;
93
94 if (len > (SSH_MAXBLOCKS * SSH_BLOCKSIZE) ||
95 len % SSH_BLOCKSIZE != 0) {
96 fatal("detect_attack: bad length %d", len);
97 }
98 for (l = n; l < HASH_FACTOR(len / SSH_BLOCKSIZE); l = l << 2)
99 ;
100

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94 if (len > (SSH_MAXBLOCKS * SSH_BLOCKSIZE) ||
95 len % SSH_BLOCKSIZE != 0) {
96 fatal("detect_attack: bad length %d", len);
97 }
98 for (l = n; l < HASH_FACTOR(len / SSH_BLOCKSIZE); l = l << 2)
99 ;
100

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