mirror of
https://gitlab.com/cryptsetup/cryptsetup.git
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1a10c59b97
git-svn-id: https://cryptsetup.googlecode.com/svn/trunk@82 36d66b0a-2a48-0410-832c-cd162a569da5
141 lines
3.6 KiB
C
141 lines
3.6 KiB
C
/*
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* AFsplitter - Anti forensic information splitter
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* Copyright 2004, Clemens Fruhwirth <clemens@endorphin.org>
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* Copyright (C) 2009 Red Hat, Inc. All rights reserved.
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*
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* AFsplitter diffuses information over a large stripe of data,
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* therefor supporting secure data destruction.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* version 2 as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Library General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*/
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#include <stddef.h>
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#include <stdlib.h>
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#include <string.h>
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#include <netinet/in.h>
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#include <errno.h>
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#include <gcrypt.h>
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#include "random.h"
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static void XORblock(char const *src1, char const *src2, char *dst, size_t n)
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{
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size_t j;
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for(j = 0; j < n; ++j)
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dst[j] = src1[j] ^ src2[j];
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}
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static int hash_buf(char *src, char *dst, uint32_t iv, int len, int hash_id)
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{
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gcry_md_hd_t hd;
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unsigned char *digest;
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iv = htonl(iv);
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if (gcry_md_open(&hd, hash_id, 0))
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return 1;
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gcry_md_write(hd, (unsigned char *)&iv, sizeof(iv));
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gcry_md_write(hd, src, len);
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digest = gcry_md_read(hd, hash_id);
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memcpy(dst, digest, len);
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gcry_md_close(hd);
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return 0;
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}
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/* diffuse: Information spreading over the whole dataset with
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* the help of hash function.
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*/
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static int diffuse(char *src, char *dst, size_t size, int hash_id)
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{
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unsigned int digest_size = gcry_md_get_algo_dlen(hash_id);
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unsigned int i, blocks, padding;
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blocks = size / digest_size;
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padding = size % digest_size;
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for (i = 0; i < blocks; i++)
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if(hash_buf(src + digest_size * i,
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dst + digest_size * i,
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i, digest_size, hash_id))
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return 1;
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if(padding)
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if(hash_buf(src + digest_size * i,
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dst + digest_size * i,
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i, padding, hash_id))
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return 1;
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return 0;
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}
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/*
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* Information splitting. The amount of data is multiplied by
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* blocknumbers. The same blocksize and blocknumbers values
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* must be supplied to AF_merge to recover information.
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*/
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int AF_split(char *src, char *dst, size_t blocksize, unsigned int blocknumbers, const char *hash)
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{
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unsigned int i;
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char *bufblock;
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int r = -EINVAL;
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int hash_id;
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if (!(hash_id = gcry_md_map_name(hash)))
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return -EINVAL;
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if((bufblock = calloc(blocksize, 1)) == NULL) return -ENOMEM;
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/* process everything except the last block */
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for(i=0; i<blocknumbers-1; i++) {
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r = getRandom(dst+(blocksize*i),blocksize);
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if(r < 0) goto out;
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XORblock(dst+(blocksize*i),bufblock,bufblock,blocksize);
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if(diffuse(bufblock, bufblock, blocksize, hash_id))
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goto out;
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}
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/* the last block is computed */
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XORblock(src,bufblock,dst+(i*blocksize),blocksize);
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r = 0;
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out:
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free(bufblock);
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return r;
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}
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int AF_merge(char *src, char *dst, size_t blocksize, unsigned int blocknumbers, const char *hash)
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{
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unsigned int i;
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char *bufblock;
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int r = -EINVAL;
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int hash_id;
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if (!(hash_id = gcry_md_map_name(hash)))
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return -EINVAL;
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if((bufblock = calloc(blocksize, 1)) == NULL) return -ENOMEM;
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memset(bufblock,0,blocksize);
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for(i=0; i<blocknumbers-1; i++) {
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XORblock(src+(blocksize*i),bufblock,bufblock,blocksize);
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if(diffuse(bufblock, bufblock, blocksize, hash_id))
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goto out;
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}
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XORblock(src + blocksize * i, bufblock, dst, blocksize);
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r = 0;
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out:
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free(bufblock);
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return 0;
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}
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