ByBahaa Zaid

bzaid@arxict.com2009-01-13

AgendaIntroduction to SecurityJava SecurityXML SecurityWS-Security

Introduction to SecurityCryptography

Symmetric-Key Cryptography Public-Key Cryptography

Public Key Infrastructure Cryptographic Hash Function Digital Signature

CryptographyIs the practice and study of hiding informationEncryption is the process of transforming information

(plaintext) using an algorithm (cipher) to make it unreadable to anyone (ciphertext) except those possessing special knowledge (key).

Decryption is to make the encrypted information readable again.

Symmetric-Key CryptographySymmetric-key cryptography refers to encryption

methods in which both the sender and receiver share the same key. This was the only kind of encryption publicly known until June 1976.

Examples are DES, 3DES, Blowfish, RC4…

Symmetric-Key CryptographyPlaintext CiphertextCipher

PlaintextCiphertext Cipher

Public-Key CryptographyPublic-Key Cryptography, also known as Asymmetric

Cryptography, is a form of cryptography in which the key used to encrypt a message differs from the key used to decrypt it. In public key cryptography, a user has a pair of cryptographic keys—a Public Key and a Private Key.

Examples are RSA and ElGamal.

Public-Key CryptographyA big random number is

used to create a key pair. When the keys have been made the big random number is thrown away. Without knowledge of the random number it should be "impossible" to create the private key from the public key.

Public-Key Cryptography A message encrypted

with a recipient's public key cannot be decrypted by anyone except the recipient possessing the corresponding private key.

Public Key Infrastructure Public Key Infrastructure (PKI) is an arrangement that

binds public keys with respective user identities by means of a Certificate Authority (CA).

CA is an example of Trusted Third Party (TTP).A CA is an entity which issues Public Key Certificate for

use by other parties.

Public Key Infrastructure The most common certificate standard is the ITU-

T X.509. A Public Key Certificate is an electronic document which

incorporates a Digital Signature to bind together a public key with an identity — information such as the name of a person or an organization, their address, and so forth.

A Public Key Certificate is the Public Key of an individual added to it his/her Identity and signed by a CA.

The certificate can be used to verify that a Public Key belongs to an individual .

Public Key Infrastructure A Certificate Chain is a sequence of certificates, where

each certificate in the chain is signed by the subsequent certificate. The last certificate in the chain is normally a self-signed Certificate - a certificate that signs itself (Root Certificate).

It’s an example of Chain Of Trust.

CA Cert(Root Cert)

signs

Company CA

signs App Certsigns

Cryptographic Hash FunctionA Cryptographic Hash Function is an algorithm that takes

an arbitrary block of data and returns a fixed-size bit string, the Hash Value or Message Digest, such that an accidental or intentional change to the data will almost certainly change the Hash Value.

Examples are MD5, SHA-1 and SHA-256.Applications are Message Integrity Verification, Digital

Signatures, …

Cryptographic Hash FunctionThe ideal hash function has four main properties:

It is easy to compute the hash for any given data,It is extremely difficult to construct a text that has a given

hash,It is extremely difficult to modify a given text without

changing its hash, andIt is extremely unlikely that two different messages will

have the same hash.

Digital SignatureFor messages sent through an insecure channel, a

properly implemented Digital Signature gives the receiver reason to believe the message was sent by the claimed sender.

Digital Signature gives both Authentication and Integrity.

Digital Signature

Java SecuritySun’s website says:

“Java security technology includes a large set of APIs, tools, and implementations of commonly used security algorithms, mechanisms, and protocols. The Java security APIs span a wide range of areas, including cryptography, public key infrastructure, secure communication, authentication, and access control.”

Platform Security is built-in language security features enforced by the Java compiler and virtual machine for example Bytecode verification, Secure class loading .

Java SecurityAccess Control is a comprehensive policy and

permissions API that allows the developer to create and administer applications requiring fine-grained access to security-sensitive resources.

Java includes APIs for Cryptography , Secure Communications (e.g. TLS) and PKI.

Java Security is Extensible i.e. Java provide the interfaces and the implementation is provided by a Security Provider, JRE has a default provider (SUN provider).

Unlimited Strength Policy FilesBy default, JRE is restricted to a particular Encryption

Algorithms and Key Lengths (Strong Encryption).This restriction is in place so that the JRE and Java

Applications that use Encryption can be freely imported by countries whose government restrict the use of Cryptography.

There are no restrictions in Egypt. So, you can download the Unlimited Strength Policy Files from Sun’s website and install it to enable unlimited encryption.

Example: Computing The Hash of a byte[]MessageDigest msgDigest = MessageDigest.getInstance("MD5");

msgDigest.update(plainText); //byte[]

byte[] digest = msgDigest.digest();

Example: Private Key CryptoKeyGenerator keyGen = KeyGenerator.getInstance("DES");

keyGen.init(56);Key key = keyGen.generateKey();…Cipher cipher = Cipher.getInstance("DES/ECB/PKCS5Padding");

cipher.init(Cipher.ENCRYPT_MODE, key);byte[] cipherText = cipher.doFinal(plainText);…cipher.init(Cipher.DECRYPT_MODE, key);byte[] newPlainText = cipher.doFinal(cipherText);

Example: Public Key CryptoKeyPairGenerator keyGen = KeyPairGenerator.getInstance("RSA");

keyGen.initialize(1024);KeyPair key = keyGen.generateKeyPair();…Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");

cipher.init(Cipher.ENCRYPT_MODE, key.getPublic());byte[] cipherText = cipher.doFinal(plainText);…cipher.init(Cipher.DECRYPT_MODE, key.getPrivate());byte[] newPlainText = cipher.doFinal(cipherText);

Example: Digital Signature

Example: Accessing Key Stores

Example: Accessing Key Stores

Serializing a Key

Serializing a Certificate

Example: Generating a CertificateStandard Java does not have an X509Certificate

generation APIBouncyCastle has a class for generating X509Certificate

instance org.bouncycastle.x509.X509V3CertificateGenerator

Example: Generating a Certificate

XML SignatureXML Signature (also called XMLDsig, XML-DSig, XML-Sig)

is a W3C recommendation that defines an XML syntax for digital signatures.

An XML signature used to sign a resource outside its containing XML document is called a detached signature;

If it is used to sign some part of its containing document, it is called an enveloped signature;

If it contains the signed data within itself it is called an enveloping signature.

XML SignatureXML Resource

XML SignatureXML Signature

Signed Data

XML Resource

XML SignatureXML Signature

Signed XML Element

XML Resource

XML Signature 1

XML Signature 1

Signed XML Element

XML Signature 2

XML Signature 2

Detached Enveloping Enveloped

XML SignatureImplementation:

Apache XML Security (santuario)Standard XML Digital Signature API (JDK 6), also

implemented in Apache XML Security for pre-6 JDKs

XML Signature

XML Signature

XML Signature

Referenceshttp://www.wikipedia.orghttp://java.sun.com/javase/technologies/security/ http://java.sun.com/security/reference/docs/index.html

More Resourceshttp://www.ibm.com/developerworks/edu/j-dw-

javasec1-i.html http://www.ibm.com/developerworks/edu/j-dw-

javasec2-i.html