| Decrypter |
/*--
This file is a part of ZetaGrid, a simple and secure Grid Computing
kernel.
Copyright (c) 2001-2004 Sebastian Wedeniwski. All rights reserved.
Use in source and binary forms, with or without modification,
are permitted provided that the following conditions are met:
1. The source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
2. The origin of this software must not be misrepresented; you must
not claim that you wrote the original software. If you plan to
use this software in a product, please contact the author.
3. Altered source versions must be plainly marked as such, and must
not be misrepresented as being the original software. The author
must be informed about these changes.
4. The name of the author may not be used to endorse or promote
products derived from this software without specific prior written
permission.
THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
Version 1.9.0, February 8, 2004
This program is based on the work of:
S. Wedeniwski
--*/
package zeta.crypto;
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.math.BigInteger;
import java.util.Arrays;
import java.util.zip.ZipEntry;
import java.util.zip.ZipInputStream;
import zeta.util.Base64;
import zeta.util.StreamUtils;
/**
* Decrypts every encrypted communication from the client using
* a key establishment protocol (half-certified Diffie-Hellman)
* with keys which have a length of 1024 Bit.
**/
public class Decrypter {
/**
* @param key key for the decryption algorithm
**/
public Decrypter(Key key) {
this.key = key;
}
/**
* Decrypts a specified input stream.
* Every transfer of a result uses a key establishment protocol (half-certified Diffie-Hellman)
* with keys which have a length of 1024 Bit.
* @param privateKey decryption number (radix 32) for the half-certified Diffie-Hellman protocol
* @param inFilename name of the file which should be decrypted
* @param outFilename name of the decrypted file
* @exception IOException if an I/O error occurs.
**/
public void decrypt(String privateKey, String inFilename, String outFilename) throws IOException {
String outUnZip = outFilename + ".bz2";
File file = new File(outUnZip);
FileInputStream in = null;
FileOutputStream out = null;
try {
in = new FileInputStream(inFilename);
out = new FileOutputStream(outFilename);
if (!decrypt(in, out, new BigInteger(privateKey, 32))) {
System.err.println("file " + outFilename + " not encrypted!");
StreamUtils.close(out);
out = null;
StreamUtils.close(in);
in = null;
file.delete();
new File(inFilename).renameTo(file);
new File(outFilename).delete();
} else {
StreamUtils.close(out);
out = null;
file.delete();
new File(outFilename).renameTo(file);
}
bzip2UncompressData(outUnZip, outFilename);
if (!(new File(outFilename).exists())) {
System.err.println("unzip error!");
file.renameTo(new File(outFilename));
}
} finally {
StreamUtils.close(in);
StreamUtils.close(out);
file.delete();
}
}
/**
* Decrypts a specified input stream.
* Every transfer of a result uses a key establishment protocol (half-certified Diffie-Hellman)
* with keys which have a length of 1024 Bit.
* @param in input stream which should be decrypted
* @param out output stream for the decrypted data
* @param D decryption number for the half-certified Diffie-Hellman protocol
* @exception IOException if an I/O error occurs.
**/
private boolean decrypt(InputStream in, OutputStream out, BigInteger D) throws IOException {
final int sz = (key.getModulo().bitLength()+31)/32 - 1;
final int l = 4*sz;
int size = 0;
while (true) {
char c = (char)in.read();
if (!Character.isDigit(c)) {
if (c != ';') {
return false;
}
break;
}
size = size*10 + Character.digit(c, 10);
}
BigInteger x = IONumber.read(in);
if (x == null) {
return false;
}
x = x.modPow(D, key.getModulo()).modInverse(key.getModulo());
int j = 0;
while (true) {
BigInteger n = IONumber.read(in);
if (n == null) {
break;
}
n = n.multiply(x).mod(key.getModulo());
byte[] result = n.toByteArray();
if (result.length < l) {
byte[] tmp = new byte[l];
System.arraycopy(result, 0, tmp, l-result.length, result.length); // ToDo: Performance
Arrays.fill(tmp, 0, l-result.length, (byte)0);
result = tmp;
}
j += l;
for (int i = result.length-l; i < l; i += 4) {
byte b = result[i];
result[i] = result[i+3];
result[i+3] = b;
b = result[i+1];
result[i+1] = result[i+2];
result[i+2] = b;
}
if (j >= size) {
j -= l; size -= j;
if ((size&3) == 0) {
out.write(result, result.length-size, size);
} else {
out.write(result, result.length-size-4+(size&3), size);
}
} else {
out.write(result, result.length-l, l);
}
}
return true;
}
/**
* Decrypts the file attribute of a URL where the parameters are packed in a parameter 'param'.
* The default decryption algorithmus will be used.
* @param urlFile encrypted file attribute of a URL
* @param D decryption number for the half-certified Diffie-Hellman protocol
* @return decrypted file attribute of a URL, or <code>null</code> if the encrypted file attribute cannot be decrypted
* @exception IOException if an I/O error occurs.
**/
public String decryptURLFile(String urlFile, BigInteger D) throws IOException {
int idx = urlFile.indexOf("param=");
byte[] data = Base64.decode((idx >= 0)? urlFile.substring(idx+6) : urlFile);
ByteArrayOutputStream out = new ByteArrayOutputStream(2048);
if (decrypt(new ByteArrayInputStream(data), out, D)) {
ZipInputStream zip = new ZipInputStream(new ByteArrayInputStream(out.toByteArray()));
ZipEntry entry = zip.getNextEntry();
if (entry != null && "param".equals(entry.getName())) {
out.reset();
StreamUtils.writeData(zip, out, true, true);
return out.toString("UTF-8");
}
}
return null;
}
/**
* Uncompresses a specified file.
* @param inFilename name of the file which should be uncompressed
* @param outFilename name of the uncompressed file
* @exception IOException if an I/O error occurs.
**/
public static void bzip2UncompressData(String inFilename, String outFilename) throws IOException {
BufferedInputStream in = null;
BufferedOutputStream out = null;
org.apache.tools.bzip2.CBZip2InputStream bzin = null;
try {
in = new BufferedInputStream(new FileInputStream(inFilename));
if (in.read() != 'B' || in.read() != 'Z') {
return;
}
out = new BufferedOutputStream(new FileOutputStream(outFilename));
if (new File(inFilename).length() > 2) { // Bug if file size equal to 0
bzin = new org.apache.tools.bzip2.CBZip2InputStream(in);
for (int ch = bzin.read(); ch != -1; ch = bzin.read()) {
out.write(ch);
}
out.flush();
}
} finally {
StreamUtils.close(bzin);
StreamUtils.close(in);
StreamUtils.close(out);
}
}
private Key key;
}
| Decrypter |