Admin: 1 версия

2010-06-01T05:01:55Z

1 версия

в 17:44, 31 мая 2010

2010-05-31T17:44:27Z

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== Create a checksum ==



<source lang="java">
import java.io.FileInputStream;
import java.io.InputStream;
import java.security.MessageDigest;
public class Main {
public static void main(String args[]) throws Exception {
InputStream fis = new FileInputStream("a.exe");
byte[] buffer = new byte[1024];
MessageDigest complete = MessageDigest.getInstance("MD5");
int numRead;
do {
numRead = fis.read(buffer);
if (numRead > 0) {
complete.update(buffer, 0, numRead);
}
} while (numRead != -1);
fis.close();

byte[] b = complete.digest();
String result = "";
for (int i = 0; i < b.length; i++) {
result += Integer.toString((b[i] & 0xff) + 0x100, 16).substring(1);
}
System.out.println(result);
}
}</source>



== Cryptography Streams: True Mirror ==



<source lang="java">
import java.io.InputStream;
import java.net.URL;
import java.security.MessageDigest;
public class Main {
public static void main(String[] args) throws Exception {
URL source = new URL("http://www.a.ru");
URL mirror = new URL("http://www.b.ru");
byte[] sourceDigest = getDigestFromURL(source);
byte[] mirrorDigest = getDigestFromURL(mirror);
if (MessageDigest.isEqual(sourceDigest, mirrorDigest)) {
System.out.println(mirror + " is up to date");
} else {
System.out.println(mirror + " needs to be updated");
}
}
public static byte[] getDigestFromURL(URL u) throws Exception {
MessageDigest md5 = MessageDigest.getInstance("MD5");
InputStream in = u.openStream();
byte[] data = new byte[1024];
int bytesRead = -1;
while ((bytesRead = in.read(data)) >= 0) {
md5.update(data, 0, bytesRead);
}
return md5.digest();
}
}</source>



== Using DigestInputStream ==



<source lang="java">
import java.io.FileInputStream;
import java.io.ObjectInputStream;
import java.security.DigestInputStream;
import java.security.MessageDigest;
public class MainClass {
public static void main(String args[]) throws Exception {
FileInputStream fis = new FileInputStream("test");
MessageDigest md = MessageDigest.getInstance("SHA");
DigestInputStream dis = new DigestInputStream(fis, md);
ObjectInputStream ois = new ObjectInputStream(dis);
Object o = ois.readObject();
if (!(o instanceof String)) {
System.out.println("Unexpected data in file");
System.exit(-1);
}
String data = (String) o;
System.out.println("Got message " + data);
dis.on(false);
o = ois.readObject();
if (!(o instanceof byte[])) {
System.out.println("Unexpected data in file");
System.exit(-1);
}
byte origDigest[] = (byte[]) o;
System.out.println(MessageDigest.isEqual(md.digest(), origDigest));
}
}</source>

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Java Tutorial/Security/Digest Stream - История изменений

Admin: 1 версия

в 17:44, 31 мая 2010