How to avoid installing Unlimited Strength JCE policy files when deploying an application

Question

I have an app that uses 256-bit AES encryption which is not supported by Java out of the box  I know to get this to function correctly I install the JCE unlimited strength jars in the security folder  This is fine for me being the developer  I can install them   My question is since this app will be distributed  end users most likely will not have these policy files installed  Having the end user download these just to make the app function is not an attractive solution    Is there a way to make my app run without overwriting files on the end user machine  A third party software that can handle it without the policy files installed  Or a way to just reference these policy files from within a JAR

User · Answer

Bouncy Castle still requires jars installed as far as I can tell   I did a little test and it seemed to confirm this   http   www bouncycastle org wiki display JA1 Frequently Asked Questions

User · Answer

This is now no longer needed for Java 9  nor for any recent release of Java 6  7  or 8  Finally      Per JDK-8170157  the unlimited cryptographic policy is now enabled by default   Specific versions from the JIRA issue    Java 9  10  11  etc     Any official release  Java 8u161 or later  Available now  Java 7u171 or later  Only available through  My Oracle Support   Java 6u181 or later  Only available through  My Oracle Support     Note that if for some odd reason the old behavior is needed in Java 9  it can be set using   Security setProperty  crypto policy    limited

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For our application  we had a client server architecture and we only allowed decrypting encrypting data in the server level  Hence the JCE files are only needed there    We had another problem where we needed to update a security jar on the client machines  through JNLP  it overwrites the libraries in  java home  lib security  and the JVM on first run     That made it work

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As of JDK 8u102  the posted solutions relying on reflection will no longer work   the field that these solutions set is now final  https   bugs openjdk java net browse JDK-8149417    Looks like it s back to either  a  using Bouncy Castle  or  b  installing the JCE policy files

User · Answer

You could use method  javax crypto Cipher getMaxAllowedKeyLength String transformation    to test the available key length  use that and inform the user about what is going on  Something stating that your application is falling back to 128 bit keys due to the policy files not being installed  for example  Security conscious users will install the policy files  others will continue using weaker keys

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During installation of your program  just prompt the user and have a DOS Batch script or a Bash shell script download and copy the JCE into the proper system location   I used to have to do this for a server webservice and instead of a formal installer  I just provided scripts to setup the app before the user could run it    You can make the app un-runnable until they run the setup script   You could also make the app complain that the JCE is missing and then ask to download and restart the app

User · Answer

There are a couple of commonly quoted solutions to this problem  Unfortunately neither of these are entirely satisfactory    Install the unlimited strength policy files  While this is probably the right solution for your development workstation  it quickly becomes a major hassle  if not a roadblock  to have non-technical users install the files on every computer  There is no way to distribute the files with your program  they must be installed in the JRE directory  which may even be read-only due to permissions   Skip the JCE API and use another cryptography library such as Bouncy Castle  This approach requires an extra 1MB library  which may be a significant burden depending on the application  It also feels silly to duplicate functionality included in the standard libraries  Obviously  the API is also completely different from the usual JCE interface   BC does implement a JCE provider  but that doesn t help because the key strength restrictions are applied before handing over to the implementation   This solution also won t let you use 256-bit TLS  SSL  cipher suites  because the standard TLS libraries call the JCE internally to determine any restrictions    But then there s reflection  Is there anything you can t do using reflection   private static void removeCryptographyRestrictions         if   isRestrictedCryptography              logger fine  Cryptography restrictions removal not needed            return            try                         Do the following  but with reflection to bypass access checks                        JceSecurity isRestricted   false             JceSecurity defaultPolicy perms clear               JceSecurity defaultPolicy add CryptoAllPermission INSTANCE                       final Class lt   gt  jceSecurity   Class forName  javax crypto JceSecurity            final Class lt   gt  cryptoPermissions   Class forName  javax crypto CryptoPermissions            final Class lt   gt  cryptoAllPermission   Class forName  javax crypto CryptoAllPermission             final Field isRestrictedField   jceSecurity getDeclaredField  isRestricted            isRestrictedField setAccessible true           final Field modifiersField   Field class getDeclaredField  modifiers            modifiersField setAccessible true           modifiersField setInt isRestrictedField  isRestrictedField getModifiers    amp   Modifier FINAL           isRestrictedField set null  false            final Field defaultPolicyField   jceSecurity getDeclaredField  defaultPolicy            defaultPolicyField setAccessible true           final PermissionCollection defaultPolicy    PermissionCollection  defaultPolicyField get null            final Field perms   cryptoPermissions getDeclaredField  perms            perms setAccessible true             Map lt      gt   perms get defaultPolicy   clear             final Field instance   cryptoAllPermission getDeclaredField  INSTANCE            instance setAccessible true           defaultPolicy add  Permission  instance get null             logger fine  Successfully removed cryptography restrictions          catch  final Exception e            logger log Level WARNING   Failed to remove cryptography restrictions   e            private static boolean isRestrictedCryptography            This matches Oracle Java 7 and 8  but not Java 9 or OpenJDK      final String name   System getProperty  java runtime name        final String ver   System getProperty  java version        return name    null  amp  amp  name equals  Java TM  SE Runtime Environment                amp  amp  ver    null  amp  amp   ver startsWith  1 7      ver startsWith  1 8         Simply call removeCryptographyRestrictions   from a static initializer or such before performing any cryptographic operations   The JceSecurity isRestricted   false part is all that is needed to use 256-bit ciphers directly  however  without the two other operations  Cipher getMaxAllowedKeyLength   will still keep reporting 128  and 256-bit TLS cipher suites won t work   This code works on Oracle Java 7 and 8  and automatically skips the process on Java 9 and OpenJDK where it s not needed  Being an ugly hack after all  it likely doesn t work on other vendors  VMs   It also doesn t work on Oracle Java 6  because the private JCE classes are obfuscated there  The obfuscation does not change from version to version though  so it is still technically possible to support Java 6

User · Answer

Here s a updated version of ntoskrnl answer  It additionally contains a function  to remove the final modifier like Arjan mentioned in the comments   This version works with JRE 8u111 or newer   private static void removeCryptographyRestrictions         if   isRestrictedCryptography              return            try                         Do the following  but with reflection to bypass access checks                         JceSecurity isRestricted   false  JceSecurity defaultPolicy perms clear               JceSecurity defaultPolicy add CryptoAllPermission INSTANCE                       final Class lt   gt  jceSecurity   Class forName  javax crypto JceSecurity            final Class lt   gt  cryptoPermissions   Class forName  javax crypto CryptoPermissions            final Class lt   gt  cryptoAllPermission   Class forName  javax crypto CryptoAllPermission             Field isRestrictedField   jceSecurity getDeclaredField  isRestricted            isRestrictedField setAccessible true           setFinalStatic isRestrictedField  true           isRestrictedField set null  false            final Field defaultPolicyField   jceSecurity getDeclaredField  defaultPolicy            defaultPolicyField setAccessible true           final PermissionCollection defaultPolicy    PermissionCollection  defaultPolicyField get null            final Field perms   cryptoPermissions getDeclaredField  perms            perms setAccessible true             Map lt      gt   perms get defaultPolicy   clear             final Field instance   cryptoAllPermission getDeclaredField  INSTANCE            instance setAccessible true           defaultPolicy add  Permission  instance get null              catch  final Exception e            e printStackTrace             static void setFinalStatic Field field  Object newValue  throws Exception         field setAccessible true          Field modifiersField   Field class getDeclaredField  modifiers          modifiersField setAccessible true         modifiersField setInt field  field getModifiers    amp   Modifier FINAL          field set null  newValue         private static boolean isRestrictedCryptography            This simply matches the Oracle JRE  but not OpenJDK      return  Java TM  SE Runtime Environment  equals System getProperty  java runtime name

User · Answer

Here is solution  http   middlesphere-1 blogspot ru 2014 06 this-code-allows-to-break-limit-if html    this code allows to break limit if client jdk jre has no unlimited policy files for JCE    it should be run once  So this static section is always execute during the class loading process    this code is useful when working with Bouncycastle library  static       try           Field field   Class forName  javax crypto JceSecurity   getDeclaredField  isRestricted            field setAccessible true           field set null  java lang Boolean FALSE         catch  Exception ex

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Here is a modified version of  ntoskrnl s code featuring isRestrictedCryptography check by actual Cipher getMaxAllowedKeyLength  slf4j logging and support of singleton initialization from application bootstrap like this   static       UnlimitedKeyStrengthJurisdictionPolicy ensure        This code would correctly stop mangling with reflection when unlimited policy becomes available by default in Java 8u162 as  cranphin s answer predicts     import org slf4j Logger  import org slf4j LoggerFactory   import javax crypto Cipher  import java lang reflect Field  import java lang reflect Modifier  import java security NoSuchAlgorithmException  import java security Permission  import java security PermissionCollection  import java util Map      https   stackoverflow com questions 1179672 how-to-avoid-installing-unlimited-strength-jce-policy-files-when-deploying-an public class UnlimitedKeyStrengthJurisdictionPolicy        private static final Logger log   LoggerFactory getLogger UnlimitedKeyStrengthJurisdictionPolicy class        private static boolean isRestrictedCryptography   throws NoSuchAlgorithmException           return Cipher getMaxAllowedKeyLength  AES ECB NoPadding    lt   128             private static void removeCryptographyRestrictions             try               if   isRestrictedCryptography                      log debug  Cryptography restrictions removal not needed                    return                                              Do the following  but with reflection to bypass access checks                                JceSecurity isRestricted   false                 JceSecurity defaultPolicy perms clear                   JceSecurity defaultPolicy add CryptoAllPermission INSTANCE                               Class lt   gt  jceSecurity   Class forName  javax crypto JceSecurity                Class lt   gt  cryptoPermissions   Class forName  javax crypto CryptoPermissions                Class lt   gt  cryptoAllPermission   Class forName  javax crypto CryptoAllPermission                 Field isRestrictedField   jceSecurity getDeclaredField  isRestricted                isRestrictedField setAccessible true               Field modifiersField   Field class getDeclaredField  modifiers                modifiersField setAccessible true               modifiersField setInt isRestrictedField  isRestrictedField getModifiers    amp   Modifier FINAL               isRestrictedField set null  false                Field defaultPolicyField   jceSecurity getDeclaredField  defaultPolicy                defaultPolicyField setAccessible true               PermissionCollection defaultPolicy    PermissionCollection  defaultPolicyField get null                Field perms   cryptoPermissions getDeclaredField  perms                perms setAccessible true                 Map lt      gt   perms get defaultPolicy   clear                 Field instance   cryptoAllPermission getDeclaredField  INSTANCE                instance setAccessible true               defaultPolicy add  Permission  instance get null                 log info  Successfully removed cryptography restrictions              catch  Exception e                log warn  Failed to remove cryptography restrictions   e                        static           removeCryptographyRestrictions               public static void ensure                just force loading of this class

User · Answer

For an alternative cryptography library  have a look at Bouncy Castle   It has AES and a lot of added functionality  It s a liberal open source library  You will have to use the lightweight  proprietary Bouncy Castle API for this to work though

[java] How to avoid installing "Unlimited Strength" JCE policy files when deploying an application?

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