// An encryption tool // Apart of Ex1 for Intro. to Comp. Sec. import java.io.Console; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.RandomAccessFile; import java.security.Key; import java.security.KeyStore; import java.security.PublicKey; import java.security.SecureRandom; import java.security.Security; import java.security.cert.Certificate; import javax.crypto.Cipher; import javax.crypto.KeyGenerator; import javax.crypto.spec.IvParameterSpec; import javax.crypto.spec.SecretKeySpec; //The standard Java crypto libraries don't do CCM mode as default, // so we will need another provider. import org.bouncycastle.jce.provider.BouncyCastleProvider; public class EncTool { static String inFile = "plainText.txt"; static String outFile = "cipherText.enc"; static String hexKey="3eafda76cd8b015641cb946708675423"; static String keyStore; static String keyName; public static void main(String[] args) { // Handle the command line arguments if (args.length==4 && args[0].equals("-encAESCTR") && args[1].length()==32 ) { hexKey = args[1]; inFile = args[2]; outFile = args[3]; encryptAESCTR(); } else if (args.length==4 && args[0].equals("-decAESCTR") &&args[1].length()==32 ) { hexKey = args[1]; inFile = args[2]; outFile = args[3]; decryptAESCTR(); } else if (args.length==4 && args[0].equals("-encAESCCM") && args[1].length()==32 ) { hexKey = args[1]; inFile = args[2]; outFile = args[3]; encryptAESCCM(); } else if (args.length==4 && args[0].equals("-decAESCCM") &&args[1].length()==32 ) { hexKey = args[1]; inFile = args[2]; outFile = args[3]; decryptAESCCM(); } else if (args.length==5 && args[0].equals("-encRSA") ) { keyStore = args[1]; keyName = args[2]; inFile = args[3]; outFile = args[4]; encryptRSA(); } else if (args.length==5 && args[0].equals("-decRSA") ) { keyStore = args[1]; keyName = args[2]; inFile = args[3]; outFile = args[4]; decryptRSA(); } else if (args.length==1 && args[0].equals("-genAES")) { generateKey(); } else { System.out.println("This is a simple program to encrypt and decrypt files"); System.out.println("Usage: "); System.out.println(" -encAESCTR AES CTR mode encrypt"); System.out.println(" -decAESCTR AES CTR mode decrypt"); System.out.println(" -encAESCCM AES CCM mode encrypt"); System.out.println(" -decAESCCM AES CCM modedecrypt"); System.out.println(" -encRSA RSA encrypt"); System.out.println(" -decRSA RSA decrypt"); System.out.println(" -genAES generate an AES key");} } private static void encryptRSA() { try { //Get the public key from the keyStore and set up the Cipher object PublicKey publicKey = getPubKey(keyStore,keyName); Cipher rsaCipher = Cipher.getInstance("RSA"); rsaCipher.init(Cipher.ENCRYPT_MODE, publicKey); //Read the plainText System.out.println("Loading plaintext file: "+inFile); RandomAccessFile rawDataFromFile = new RandomAccessFile(inFile, "r"); byte[] plainText = new byte[(int)rawDataFromFile.length()]; rawDataFromFile.read(plainText); // Generate a symmetric key to encrypt the data and initiate the AES Cipher Object System.out.println("Generating AES key"); KeyGenerator sKenGen = KeyGenerator.getInstance("AES"); Key aesKey = sKenGen.generateKey(); Cipher aesCipher = Cipher.getInstance("AES"); aesCipher.init(Cipher.ENCRYPT_MODE, aesKey); // Encrypt the symmetric AES key with the public RSA key System.out.println("Encrypting Data"); byte[] encodedKey = rsaCipher.doFinal(aesKey.getEncoded()); // Encrypt the plaintext with the AES key byte[] cipherText = aesCipher.doFinal(plainText); //Write the encrypted AES key and Ciphertext to the file. System.out.println("Writting to file: "+outFile); FileOutputStream outToFile = new FileOutputStream(outFile); outToFile.write(encodedKey); outToFile.write(cipherText); System.out.println("Closing Files"); rawDataFromFile.close(); outToFile.close(); } catch (Exception e) { System.out.println("Doh: "+e); } } private static PublicKey getPubKey(String keyStoreFile, String keyName) { PublicKey publicKey = null; try { // Load the keyStore KeyStore myKeyStore = KeyStore.getInstance("JKS"); FileInputStream inStream = new FileInputStream(keyStoreFile); //Get the keyStore password, using Console lets us mask the password Console console = System.console(); char[] password = console.readPassword("Enter your secret password: "); myKeyStore.load(inStream, password); Certificate cert = myKeyStore.getCertificate(keyName); publicKey = cert.getPublicKey(); } catch (Exception e) { System.out.println("Doh: "+e); } return publicKey; } private static void decryptRSA() { System.out.println("RSA Decryption not yet supported"); } private static void decryptAESCTR() { try{ FileInputStream encryptesKeyWithIV = new FileInputStream(outFile); byte[] initVector = new byte[16]; byte[] encryptedKey = null; IvParameterSpec ivSpec = new IvParameterSpec(initVector); SecretKeySpec skeySpec = new SecretKeySpec(hexStringToByteArray(hexKey), "AES"); Cipher decAESCTRcipher = Cipher.getInstance("AES/CBC/PKCS5PADDING"); decAESCTRcipher.init(Cipher.DECRYPT_MODE, skeySpec, ivSpec); byte[] plainText = decAESCTRcipher.doFinal(encryptedKey); System.out.println("Openning file to write: "+inFile); FileOutputStream inToFile = new FileOutputStream(inFile); inToFile.write(initVector); inToFile.write(plainText); inToFile.close(); System.out.println(outFile+" decrypted as "+inFile); } catch (Exception e) { System.out.println("doh "+e); } } private static void decryptAESCCM() { System.out.println("AES CCM Decryption not yet supported"); } private static void generateKey() { try { KeyGenerator sGen = KeyGenerator.getInstance("AES"); Key aesKey = sGen.generateKey(); System.out.println("Here are some bytes you can use as an AES key: "+byteArrayToHexString(aesKey.getEncoded())); } catch (Exception e){ System.out.println("doh "+e); } } private static void encryptAESCTR() { try { // Open and read the input file // N.B. this program reads the whole file into memory, not good for large programs! RandomAccessFile rawDataFromFile = new RandomAccessFile(inFile, "r"); byte[] plainText = new byte[(int) rawDataFromFile.length()]; rawDataFromFile.read(plainText); rawDataFromFile.close(); //Set up the AES key & cipher object in CTR mode SecretKeySpec secretKeySpec = new SecretKeySpec(hexStringToByteArray(hexKey), "AES"); Cipher encAESCTRcipher = Cipher.getInstance("AES/CTR/PKCS5Padding"); SecureRandom random = new SecureRandom(); byte iv[] = new byte[16]; random.nextBytes(iv); IvParameterSpec ivSpec = new IvParameterSpec(iv); encAESCTRcipher.init(Cipher.ENCRYPT_MODE, secretKeySpec,ivSpec); //Encrypt the data byte[] cipherText = encAESCTRcipher.doFinal(plainText); //Write file to disk System.out.println("Openning file to write: "+outFile); FileOutputStream outToFile = new FileOutputStream(outFile); outToFile.write(iv); outToFile.write(cipherText); outToFile.close(); System.out.println(inFile+" encrypted as "+outFile); } catch (Exception e){ System.out.println("doh "+e); } } private static void encryptAESCCM() { try { // Open and read the input file // N.B. this program reads the whole file into memory, not good for large programs! RandomAccessFile rawDataFromFile = new RandomAccessFile(inFile, "r"); byte[] plainText = new byte[(int) rawDataFromFile.length()]; rawDataFromFile.read(plainText); rawDataFromFile.close(); //Set up the AES key & cipher object in CCM mode SecretKeySpec secretKeySpec = new SecretKeySpec(hexStringToByteArray(hexKey), "AES"); // Add a security provider that actually does provide CCM mode Security.insertProviderAt(new BouncyCastleProvider(), 1); Cipher encAESCCMcipher = Cipher.getInstance("AES/CCM/NoPadding","BC"); SecureRandom random = new SecureRandom(); byte iv[] = new byte[10]; // BC needs us to leave room for the counter random.nextBytes(iv); IvParameterSpec ivSpec = new IvParameterSpec(iv); encAESCCMcipher.init(Cipher.ENCRYPT_MODE, secretKeySpec,ivSpec); //Encrypt the data byte[] cipherText = encAESCCMcipher.doFinal(plainText); //Write file to disk System.out.println("Openning file to write: "+outFile); FileOutputStream outToFile = new FileOutputStream(outFile); outToFile.write(iv); outToFile.write(cipherText); outToFile.close(); System.out.println(inFile+" encrypted as "+outFile); } catch (Exception e){ System.out.println("doh "+e); } } // Code from http://www.anyexample.com/programming/java/java%5Fsimple%5Fclass%5Fto%5Fcompute%5Fmd5%5Fhash.xml private static String byteArrayToHexString(byte[] data) { StringBuffer buf = new StringBuffer(); for (int i = 0; i < data.length; i++) { int halfbyte = (data[i] >>> 4) & 0x0F; int two_halfs = 0; do { if ((0 <= halfbyte) && (halfbyte <= 9)) buf.append((char) ('0' + halfbyte)); else buf.append((char) ('a' + (halfbyte - 10))); halfbyte = data[i] & 0x0F; } while(two_halfs++ < 1); } return buf.toString(); } // Code from http://javaconversions.blogspot.co.uk private static byte[] hexStringToByteArray(String s) { int len = s.length(); byte[] data = new byte[len / 2]; for (int i = 0; i < len; i += 2) { data[i / 2] = (byte) ((Character.digit(s.charAt(i), 16) << 4) + Character.digit(s.charAt(i+1), 16)); } return data; } }

encryption&decryption