Java Encryption: Key Generation and Ciphering Techniques

1. Java Ciphers copy jar files onto your machine & include in CLASSPATH Java supports encryption by a wide variety of packages: • The standard java.security package • The standard javax.crypto package • Packages supplied by third parties www.cryptix.org www.bouncycastle.org setenv CLASSPATH .:/Users/driley/Library/bcprov-jdk15-130.jar Edit the java.security file to include the provider. # List of providers and their preference orders (see above): # security.provider.1=sun.security.provider.Sun security.provider.2=com.apple.crypto.provider.Apple ... security.provider.8=org.bouncycastle.jce.provider.BouncyCastleProvider As of Java 1.4 the SunJCE is a built-in provider. http://java.sun.com/j2se/1.5.0/docs/guide/security/jce/JCERefGuide.html

2. 1) 1) KeyGenerator generator = KeyGenerator.getInstance(“DESede”); KeyPairGenerator generator = KeyPairGenerator.getInstance(“RSA”); generator.init(new SecureRandom()); 2) Key key = generator.generateKey(); generator.initialize(2048, new SecureRandom()); 2) KeyPair keyPair = generator.generateKeyPair(); Java Key Generation The Java encryption packages include classes that are useful for generating keys. java.security.Key javax.crypto.KeyGenerator java.security.KeyPair java.security.KeyPairGenerator java.security.SecureRandom Two Steps for generating a new key (or pair) 1) Create generator key/pair by calling a static method named getInstance). 2) Call generateKey object, passing a random number. Sample Symmetric Code Sample Public-key Code

3. Ciphering in Java Four Steps for encrypting/decrypting 1) Create an encrypting object using javax.crypto.Cipher. (This is done by calling a static method named getInstance). 2) Call init on the Cipher object, passing the key & setting the mode to encrypt/decrypt. 3) Fill a byte array from plaintext to be encrypted (or ciphertext to be decrypted). 4) Call doFinal on the object, passing the byte array; this returns the result of encrypting/decrypting. • getInstance specifies algorithm via 1st argument String Algorithm/ChainingMode/Padding • getInstance specifies supplier via second (optional) argument

4. 1) 1) Cipher encoder = Cipher.getInstance(“DESede/ECB/PKCS5Padding”); Cipher decoder = Cipher.getInstance(“DESede/ECB/PKCS5Padding”); 2) 2) decoder.init(Cipher.DECRYPT_MODE, key); encoder.init(Cipher.ENCRYPT_MODE, key); 3) 3) byte[] buffer = getCiphertext(); byte[] buffer = getPlaintext(); 4) 4) byte[] decodedMsg = decoder.doFinal(buffer); byte[] encodedMsg = encoder.doFinal(buffer); must be encoder.getBlockSize() or smaller Ciphering in Java Four Steps for encrypting/decrypting 1) Create an encrypting object using javax.crypto.Cipher. (This is done by calling a static method named getInstance). 2) Call init on the Cipher object, passing the key & setting the mode to encrypt/decrypt. 3) Fill a byte array from plaintext to be encrypted (or ciphertext to be decrypted). 4) Call doFinal on the object, passing the byte array; this returns the result of encrypting/decrypting. Symmetric Sample

5. 1) Cipher encoder = Cipher.getInstance(“RSA/NONE/PKCS1Padding”, “BC”); 2) encoder.init(Cipher.ENCRYPT_MODE, keyPair.getPublic()); 3) byte[] buffer = getPlaintext(); 4) byte[] encodedMsg = encoder.doFinal(buffer); must be encoder.getBlockSize() or smaller RSA with BouncyCastle Four Steps for encrypting/decrypting 1) Create an encrypting object using javax.crypto.Cipher. (This is done by calling a static method named getInstance). 2) Call init on the Cipher object, passing the key & setting the mode to encrypt/decrypt. 3) Fill a byte array from plaintext too be encrypted (or ciphertext to be decrypted). 4) Call doFinal on the object, passing the byte array; this returns the result of encrypting/decrypting. Public-key Sample