Initial checking of what was revision 56 on http://luks.endorphin.org/svn/cryptsetup

git-svn-id: https://cryptsetup.googlecode.com/svn/trunk@3 36d66b0a-2a48-0410-832c-cd162a569da5

luks/af.c

@@ -0,0 +1,116 @@
+/*
+ * AFsplitter - Anti forensic information splitter
+ * Copyright 2004, Clemens Fruhwirth <clemens@endorphin.org>
+ *
+ * AFsplitter diffuses information over a large stripe of data, 
+ * therefor supporting secure data destruction.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ */
+ 
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <netinet/in.h>
+#include <errno.h>
+#include "sha1.h"
+#include "XORblock.h"
+#include "random.h"
+
+/* diffuse: Information spreading over the whole dataset with
+ * the help of sha512. 
+ */
+
+static void diffuse(unsigned char *src, unsigned char *dst, size_t size)
+{
+	sha1_ctx ctx;
+	uint32_t i;
+	uint32_t IV;	/* host byte order independend hash IV */
+	
+	unsigned int fullblocks = size / SHA1_DIGEST_SIZE;
+	unsigned int padding = size % SHA1_DIGEST_SIZE;
+	unsigned char final[SHA1_DIGEST_SIZE];
+
+	/* hash block the whole data set with different IVs to produce
+	 * more than just a single data block
+	 */
+	for (i=0; i < fullblocks; i++) {
+		sha1_begin(&ctx);
+		IV = htonl(i);
+		sha1_hash((const unsigned char *) &IV, sizeof(IV), &ctx);
+		sha1_hash(src + SHA1_DIGEST_SIZE * i, SHA1_DIGEST_SIZE, &ctx);
+		sha1_end(dst + SHA1_DIGEST_SIZE * i, &ctx);
+	}
+
+	if(padding) {
+		sha1_begin(&ctx);
+		IV = htonl(i);
+		sha1_hash((const unsigned char *) &IV, sizeof(IV), &ctx);
+		sha1_hash(src + SHA1_DIGEST_SIZE * i, padding, &ctx);
+		sha1_end(final, &ctx);
+ 		memcpy(dst + SHA1_DIGEST_SIZE * i, final, padding);
+	}
+}
+
+/*
+ * Information splitting. The amount of data is multiplied by
+ * blocknumbers. The same blocksize and blocknumbers values 
+ * must be supplied to AF_merge to recover information.
+ */
+
+int AF_split(char *src, char *dst, size_t blocksize, unsigned int blocknumbers)
+{
+	unsigned int i;
+	char *bufblock;
+	int r = -EINVAL;
+
+	if((bufblock = calloc(blocksize, 1)) == NULL) return -ENOMEM;
+
+	/* process everything except the last block */
+	for(i=0; i<blocknumbers-1; i++) {
+		r = getRandom(dst+(blocksize*i),blocksize);
+		if(r < 0) goto out;
+
+		XORblock(dst+(blocksize*i),bufblock,bufblock,blocksize);
+		diffuse(bufblock,bufblock,blocksize);
+	}
+	/* the last block is computed */
+	XORblock(src,bufblock,dst+(i*blocksize),blocksize);
+	r = 0;
+out:
+	free(bufblock);
+	return r;
+}
+
+int AF_merge(char *src, char *dst, size_t blocksize, unsigned int blocknumbers)
+{
+	unsigned int i;
+	char *bufblock;
+
+	if((bufblock = calloc(blocksize, 1)) == NULL) return -ENOMEM;
+
+	memset(bufblock,0,blocksize);
+	for(i=0; i<blocknumbers-1; i++) {
+		XORblock(src+(blocksize*i),bufblock,bufblock,blocksize);
+		diffuse(bufblock,bufblock,blocksize);
+	}
+	XORblock(src + blocksize * i, bufblock, dst, blocksize);
+
+	free(bufblock);	
+	return 0;
+}