From e7e9a66629ada359ad6a35cdb12e0e35b49e889c Mon Sep 17 00:00:00 2001 From: marha Date: Fri, 7 Aug 2009 12:33:59 +0000 Subject: Added plink tool (version without console, except if output is generated) Added possibility to build console application or windows application in makefile.after --- tools/plink/sshcrcda.c | 172 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 172 insertions(+) create mode 100644 tools/plink/sshcrcda.c (limited to 'tools/plink/sshcrcda.c') diff --git a/tools/plink/sshcrcda.c b/tools/plink/sshcrcda.c new file mode 100644 index 000000000..c2cf705b2 --- /dev/null +++ b/tools/plink/sshcrcda.c @@ -0,0 +1,172 @@ +/* $OpenBSD: deattack.c,v 1.14 2001/06/23 15:12:18 itojun Exp $ */ + +/* + * Cryptographic attack detector for ssh - source code + * + * Copyright (c) 1998 CORE SDI S.A., Buenos Aires, Argentina. + * + * All rights reserved. Redistribution and use in source and binary + * forms, with or without modification, are permitted provided that + * this copyright notice is retained. + * + * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED + * WARRANTIES ARE DISCLAIMED. IN NO EVENT SHALL CORE SDI S.A. BE + * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY OR + * CONSEQUENTIAL DAMAGES RESULTING FROM THE USE OR MISUSE OF THIS + * SOFTWARE. + * + * Ariel Futoransky + * + * + * Modified for use in PuTTY by Simon Tatham + */ + +#include +#include "misc.h" +#include "ssh.h" + +typedef unsigned char uchar; +typedef unsigned short uint16; + +/* SSH Constants */ +#define SSH_MAXBLOCKS (32 * 1024) +#define SSH_BLOCKSIZE (8) + +/* Hashing constants */ +#define HASH_MINSIZE (8 * 1024) +#define HASH_ENTRYSIZE (sizeof(uint16)) +#define HASH_FACTOR(x) ((x)*3/2) +#define HASH_UNUSEDCHAR (0xff) +#define HASH_UNUSED (0xffff) +#define HASH_IV (0xfffe) + +#define HASH_MINBLOCKS (7*SSH_BLOCKSIZE) + +/* Hash function (Input keys are cipher results) */ +#define HASH(x) GET_32BIT_MSB_FIRST(x) + +#define CMP(a, b) (memcmp(a, b, SSH_BLOCKSIZE)) + +uchar ONE[4] = { 1, 0, 0, 0 }; +uchar ZERO[4] = { 0, 0, 0, 0 }; + +struct crcda_ctx { + uint16 *h; + uint32 n; +}; + +void *crcda_make_context(void) +{ + struct crcda_ctx *ret = snew(struct crcda_ctx); + ret->h = NULL; + ret->n = HASH_MINSIZE / HASH_ENTRYSIZE; + return ret; +} + +void crcda_free_context(void *handle) +{ + struct crcda_ctx *ctx = (struct crcda_ctx *)handle; + if (ctx) { + sfree(ctx->h); + ctx->h = NULL; + sfree(ctx); + } +} + +static void crc_update(uint32 *a, void *b) +{ + *a = crc32_update(*a, b, 4); +} + +/* detect if a block is used in a particular pattern */ +static int check_crc(uchar *S, uchar *buf, uint32 len, uchar *IV) +{ + uint32 crc; + uchar *c; + + crc = 0; + if (IV && !CMP(S, IV)) { + crc_update(&crc, ONE); + crc_update(&crc, ZERO); + } + for (c = buf; c < buf + len; c += SSH_BLOCKSIZE) { + if (!CMP(S, c)) { + crc_update(&crc, ONE); + crc_update(&crc, ZERO); + } else { + crc_update(&crc, ZERO); + crc_update(&crc, ZERO); + } + } + return (crc == 0); +} + +/* Detect a crc32 compensation attack on a packet */ +int detect_attack(void *handle, uchar *buf, uint32 len, uchar *IV) +{ + struct crcda_ctx *ctx = (struct crcda_ctx *)handle; + register uint32 i, j; + uint32 l; + register uchar *c; + uchar *d; + + assert(!(len > (SSH_MAXBLOCKS * SSH_BLOCKSIZE) || + len % SSH_BLOCKSIZE != 0)); + for (l = ctx->n; l < HASH_FACTOR(len / SSH_BLOCKSIZE); l = l << 2) + ; + + if (ctx->h == NULL) { + ctx->n = l; + ctx->h = snewn(ctx->n, uint16); + } else { + if (l > ctx->n) { + ctx->n = l; + ctx->h = sresize(ctx->h, ctx->n, uint16); + } + } + + if (len <= HASH_MINBLOCKS) { + for (c = buf; c < buf + len; c += SSH_BLOCKSIZE) { + if (IV && (!CMP(c, IV))) { + if ((check_crc(c, buf, len, IV))) + return 1; /* attack detected */ + else + break; + } + for (d = buf; d < c; d += SSH_BLOCKSIZE) { + if (!CMP(c, d)) { + if ((check_crc(c, buf, len, IV))) + return 1; /* attack detected */ + else + break; + } + } + } + return 0; /* ok */ + } + memset(ctx->h, HASH_UNUSEDCHAR, ctx->n * HASH_ENTRYSIZE); + + if (IV) + ctx->h[HASH(IV) & (ctx->n - 1)] = HASH_IV; + + for (c = buf, j = 0; c < (buf + len); c += SSH_BLOCKSIZE, j++) { + for (i = HASH(c) & (ctx->n - 1); ctx->h[i] != HASH_UNUSED; + i = (i + 1) & (ctx->n - 1)) { + if (ctx->h[i] == HASH_IV) { + if (!CMP(c, IV)) { + if (check_crc(c, buf, len, IV)) + return 1; /* attack detected */ + else + break; + } + } else if (!CMP(c, buf + ctx->h[i] * SSH_BLOCKSIZE)) { + if (check_crc(c, buf, len, IV)) + return 1; /* attack detected */ + else + break; + } + } + ctx->h[i] = j; + } + return 0; /* ok */ +} -- cgit v1.2.3