Java Security

Session 19

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Objectives

Discuss Java cryptography

Explain the Java Security Model

Discuss each of the components that comprise the JSM

Describe the security tools available as part of the Java platform

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Introduction

Security on the Internet is a big issue today Corruption of data Denial of access to services Attacks that simply annoy users

Security model in Java2 has been enhanced to enable digitally signed applets to be run on the web

Security of precious goods is only as good as the defense mechanism employed to guard it

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Java2 security model

Byte code verifier

Class Loader

Security Manager

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Byte Code Verifier

This verifies: Byte code represent legal JVM operations Possibilities of stack overflow or underflow Byte code does not compromise the type safety of

operands Class methods observe all access specifiers such

as public, private, etc.

Examines the byte codes of a class before executing it

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Class Loader

The functions of a Class Loader include: Preventing conflict between any running programs

that may have identical class names Ensures that users do not load system classes

Byte code in this stage is assumed to be valid

Applet SecurityManager

Checks Applets

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Java Security Manager (JSM)

Applets have to be downloaded and hence can cause potential attacks

Applets can only manipulate data within a specified area (sandbox) of the hard disk

Security Manager provides a sandbox as well as allows one to create a sandbox

JSM also controls access to important resources, operations and access to files

Standalone applications are trusted by default

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Java Security Model

Applications(Trusted by default)

Applets(Untrusted by default)

System and Network Resources

Access Denied

Applications(Trusted by default)

Unsigned Applets(Untrusted by default)

System and Network Resources

Access Denied

Signed Applets(Trusted)

JDK

1.0

JDK

1.1

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java.policy file

Security policy file is located at JAVA_HOME\lib\security\java.policy where JAVA_HOME indicates location of JDK

It is possible to specify a security policy that determines the access type an application or an applet is allowed

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Safe environment in JSM

Java Code

Java Compiler

Class Files(byte code)

Byte code verifier

Class Loader

Java Interpreter

Security Manager(if present)

Executed program

Transmission over Network or local

file system

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JDK security tools

Authentication is an important and vital issue A digital signature solves two vital security

concerns Authentication Integrity

Sun offers three tools to digitally sign applets -jar, jarsigner and keytool

A system on the Internet should lookout for components that lay the system open to intruders

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The keytool utility (1)

In private cryptography, a process takes a piece of data and uses a special key such as password to produce an encrypted password

Only with the help of the key, one can decrypt the original message

Data Encryption Standard is a widely used cryptographic system

Used to create and manage public keys, private keys and security certificates

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The keytool utility (2)

Two keys that are mathematically related are created

One for encryption and the other for decryption Used for:

Managing public/private key pairs Storing public keys of people and groups Authentication of ones identity Verifying the source and integrity of data

Public key cryptography is based on mathematical algorithms

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The keytool utility (3)

One can check the existence of keystore by: keytool –list keytool –list –keystore C:\myfolder\mystore

-genkey option of keytool creates a public/private key pair

keytool –genkey –alias aliasname

While adding a key to a new keystore, a password has to be given

Information managed by keytool is stored in a database called keystore

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Creating a key pair (1)

Example:Alias: aptechkey

Organizational unit: Software Dev

Organization: Gates Corp.

City: Palo Alto, CA.

State: CA (for California)

County code:CA

Key password: aptECH2k01

keytool utility asks a number of questions when we create a new key pair

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Creating a key pair (2) The command –keytool –list –v –alias

aptechkey give the following output:

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Working with certificates (1)

Indicates that the public key of a person has important value

Digital certificates associate an identity with a public key Identity is called subject Authority that signs is called signer

Statement signed by an authority

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Working with certificates (2)

Certificates follow the X.509 standard When we create a new public/private keypair,

a self-signed certificate signed by the same entity that created the key pair is obtained keytool –alias aptechkey –certreq –file

aptechreq.txt

keytool utility can display, import and export certificates in addition to key pairs

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jar tool and jarsigner tool

jarsigner then digitally signs a java archive jarsigner MyApplet.jar aptechkey

The key must have gone through a verification process before use

Before java program can be digitally signed, it must be packaged into an archive form consisting of all class files and other files with the help of jar tool

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Java Cryptography

It also provides passwords to secure access Java.security file should include the following line:

policy.url.2=file:${user.home}/.java.policy

Java Cryptography classes enable us to encrypt and decrypt programs

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Example (1)

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Example (2)

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Output