by BehindJava
AES256 Exception in thread "main" java.security.InvalidKeyException Illegal key size or default parameters in Java
In case of developing an application using the Java Cryptography Extension, and using a key length of more than 128 bits you encounter the following error.
JDK has a deliberate key size restriction by default, so you cannot use an encryption with key more than 128 bits. There is a code only solution. No need to download or mess with configuration files. It’s a reflection based solution, tested on java 8. Call this method once, early in your program.
Sample Code Snippet:
import javax.crypto.Cipher;
import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.util.Map;
// This class overides the permissions of java crypto librariespublic class Configclass {
public static void fixKeyLength() {
String errorString = "Failed manually overriding key-length permissions.";
int newMaxKeyLength;
try {
if ((newMaxKeyLength = Cipher.getMaxAllowedKeyLength("AES")) < 256) {
Class c = Class.forName("javax.crypto.CryptoAllPermissionCollection");
Constructor con = c.getDeclaredConstructor();
con.setAccessible(true);
Object allPermissionCollection = con.newInstance();
Field f = c.getDeclaredField("all_allowed");
f.setAccessible(true);
f.setBoolean(allPermissionCollection, true);
c = Class.forName("javax.crypto.CryptoPermissions");
con = c.getDeclaredConstructor();
con.setAccessible(true);
Object allPermissions = con.newInstance();
f = c.getDeclaredField("perms");
f.setAccessible(true);
((Map) f.get(allPermissions)).put("*", allPermissionCollection);
c = Class.forName("javax.crypto.JceSecurityManager");
f = c.getDeclaredField("defaultPolicy");
f.setAccessible(true);
Field mf = Field.class.getDeclaredField("modifiers");
mf.setAccessible(true);
mf.setInt(f, f.getModifiers() & ~Modifier.FINAL);
f.set(null, allPermissions);
newMaxKeyLength = Cipher.getMaxAllowedKeyLength("AES");
}
} catch (Exception e) {
throw new RuntimeException(errorString, e);
}
if (newMaxKeyLength < 256)
throw new RuntimeException(errorString); // hack failed
}
}Share:
