1. csci5931 Web Security1 Java Security Model (GS: Ch. 7)

2. csci5931 Web Security2 Topics A. Basics of Java Security Model B. Cryptographic Signatures C. Permissions  Customized Permissions

3. csci5931 Web Security3 Basics of Java Security Model  Java 2 security is policy-based.  The policy defined in java.policy file controls the resources that Java codes have access to.  Codesource = codebase + signer  codebase: The location that the code comes from, either locally or from a remote site.  signer: the entity that signed the code in question

4. csci5931 Web Security4 Basics of Java Security Model  Permissions: specific actions that a codesource is allowed to take (e.g., access a file, connect to a machine)  Types of Java codes:  Java applications  Java applets  Java servlets  Java beans, JEB

5. csci5931 Web Security5 Managing Cryptographic Signatures  Tools provided by Sun: keytooljarsigner policytool  keytool (pp. 157-161): An application that ships with JDK It manages keystores and can create certificates. It replaces javakey, found in Java 1.1. Note: Keystores are linked to the provider (e.g., Sun’s JCA provider). A keystore file generated by one provider will not work with a keystore file generated by another provider.

6. csci5931 Web Security6 Managing Cryptographic Signatures  jarsigner A signing and verification tool for Java archive (JAR) files Attaches a specific signer to a specific set of codes Usage: jarsigner [options] jar-file alias jarsigner -verify [options] jar-file [-keystore ] keystore location [-storepass ] password for keystore integrity [-storetype ] keystore type [-keypass ] password for private key (if different) [-sigfile ] name of.SF/.DSA file [-signedjar ] name of signed JAR file [-verify] verify a signed JAR file...

7. csci5931 Web Security7 Managing Cryptographic Signatures  Jarsigner (a) It signs JAR files. (b) It verifies signatures on JAR files.  JAR (Java Archive): a.zip file that supports signatures.  To sign a JAR file: You must have a private key and a certificate in your keystore.  For your signed JAR file to be verifiable by others: Your certificate must be signed by a CA.

8. csci5931 Web Security8 Managing Cryptographic Signatures  A signed JAR file allows the user to determine whether the Java codes contained in the JAR can be trusted or not.  Applets are usually signed, if extra permissions (beyond those defined as defaults) need to be granted.  In Java 1.2.1 or higher, every class within the same package inside a signed JAR must be signed by the same certificate. Q: Why is this important?

9. csci5931 Web Security9 Managing Cryptographic Signatures  Steps in signing a JAR file: A. Use jar to create a JAR file out of the.class file(s). B. Use keytool to generate a keypair. C. Use jarsigner to sign the JAR file with the private key and the certificate.  To verify a signed JAR file: jarsigner –verify …  Example usage: p.179

10. csci5931 Web Security10 Managing Cryptographic Signatures  When a JAR is signed, it is not the JAR itself that is signed, but some or all of the files it contains.  A signed JAR contains three files:  The manifest (HelloWorld.mf)  The signature file (HelloWorld.sf)  The digital signature file (HelloWorld.dsf)

11. csci5931 Web Security11 Managing Cryptographic Signatures  To view the content of a JAR file:  Use jar command > jar tvf HelloWorld.jar 140 Wed Mar 19 10:22:24 CST 2003 META-INF/MANIFEST.MF 193 Wed Mar 19 10:22:24 CST 2003 META-INF/EXAMPLES.SF 1013 Wed Mar 19 10:22:24 CST 2003 META-INF/EXAMPLES.DSA 0 Wed Mar 19 10:13:58 CST 2003 META-INF/ 426 Wed Mar 19 10:13:30 CST 2003 HelloWorld.class  Use winzip or something like that

12. csci5931 Web Security12 Managing Permissions  The Java security manager handles the checking of permissions as needed.  The default implementation: java.lang.SecurityManager, which can be sub-classed or overwritten if necessary.  Java enforces security by asking the security manager for permissions before taking any action that is considered potentially unsafe.

13. csci5931 Web Security13 Managing Permissions  Permissions are defined in the java.policy file, which is stored in $JAVA_HOME/jre/lib/security/java.policy.  Two ways to edit java.policy file: A. Manually by using a text editor B. Use policytool, which is a GUI tool for editing Java security policies (See examples on pp.188-189)  An example: pp.182, 187 (FileWriteTest.java)

14. csci5931 Web Security14 Managing Permissions  The syntax for the grant command in java.policy file: grant signedBy “signer_names”, codeBase “URL” { permission permission_class_name “target_name”, “action”, signedBy “signer_names”; … }  See sample listing on pp.183-184.  More samples on p.186.

15. csci5931 Web Security15 Managing Permissions  Default permission classes in Java: p.190  AllPermission  BasicPermission  FilePermission  SocketPermission  Subclasses of BasicPermission:  AudioPermission, AWTPermission, NetPermission, …

16. csci5931 Web Security16 Managing Permissions  Customized Permissions:  You may want to restrict access to certain classes based on the caller’s codesource.  To prevent untrusted codes from calling some sensitive classes.  An example (p.191): extending BasicPermission by creating a subclass.

17. csci5931 Web Security17 Managing Permissions  Customized Permissions: Example > java -cp SecretWordTest.jar -Djava.security.manager - Djava.security.policy=SecretWord.policy SecretWordTest The secret word is: ossifrage

18. csci5931 Web Security18 Managing Permissions  Security properties for the JVM are defined in the java.security file, which is stored in $JAVA_HOME/jre/lib/security/java.security.  Security providers, policy provider, keystore type, etc. (pp.194- 195)

19. csci5931 Web Security19 Next  Team Presentations  SSL (GS: 9)  Applet security (GS: 7)  Servlets security (GS: 8)  …