RSA.rar_it_rsa

package com.anuj.security.encryption; import java.io.BufferedOutputStream; import java.io.File; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.IOException; import java.io.ObjectInputStream; import java.io.ObjectOutputStream; import java.math.BigInteger; import java.security.KeyFactory; import java.security.KeyPair; import java.security.KeyPairGenerator; import java.security.NoSuchAlgorithmException; import java.security.PrivateKey; import java.security.PublicKey; import java.security.spec.InvalidKeySpecException; import java.security.spec.RSAPrivateKeySpec; import java.security.spec.RSAPublicKeySpec; import javax.crypto.Cipher; /** * * @author Anuj * Blog www.goldenpackagebyanuj.blogspot.com * RSA - Encrypt Data using Public Key * RSA - Descypt Data using Private Key */ public class RSAEncryptionDecryption { private static final String PUBLIC_KEY_FILE = "Public.key"; private static final String PRIVATE_KEY_FILE = "Private.key"; public static void main(String[] args) throws IOException { try { System.out.println("-------GENRATE PUBLIC and PRIVATE KEY-------------"); KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA"); keyPairGenerator.initialize(2048); //1024 used for normal securities KeyPair keyPair = keyPairGenerator.generateKeyPair(); PublicKey publicKey = keyPair.getPublic(); PrivateKey privateKey = keyPair.getPrivate(); System.out.println("Public Key - " + publicKey); System.out.println("Private Key - " + privateKey); //Pullingout parameters which makes up Key System.out.println("\n------- PULLING OUT PARAMETERS WHICH MAKES KEYPAIR----------\n"); KeyFactory keyFactory = KeyFactory.getInstance("RSA"); RSAPublicKeySpec rsaPubKeySpec = keyFactory.getKeySpec(publicKey, RSAPublicKeySpec.class); RSAPrivateKeySpec rsaPrivKeySpec = keyFactory.getKeySpec(privateKey, RSAPrivateKeySpec.class); System.out.println("PubKey Modulus : " + rsaPubKeySpec.getModulus()); System.out.println("PubKey Exponent : " + rsaPubKeySpec.getPublicExponent()); System.out.println("PrivKey Modulus : " + rsaPrivKeySpec.getModulus()); System.out.println("PrivKey Exponent : " + rsaPrivKeySpec.getPrivateExponent()); //Share public key with other so they can encrypt data and decrypt thoses using private key(Don't share with Other) System.out.println("\n--------SAVING PUBLIC KEY AND PRIVATE KEY TO FILES-------\n"); RSAEncryptionDecryption rsaObj = new RSAEncryptionDecryption(); rsaObj.saveKeys(PUBLIC_KEY_FILE, rsaPubKeySpec.getModulus(), rsaPubKeySpec.getPublicExponent()); rsaObj.saveKeys(PRIVATE_KEY_FILE, rsaPrivKeySpec.getModulus(), rsaPrivKeySpec.getPrivateExponent()); //Encrypt Data using Public Key byte[] encryptedData = rsaObj.encryptData("Anuj Patel - Classified Information !"); //Descypt Data using Private Key rsaObj.decryptData(encryptedData); } catch (NoSuchAlgorithmException e) { e.printStackTrace(); }catch (InvalidKeySpecException e) { e.printStackTrace(); } } /** * Save Files * @param fileName * @param mod * @param exp * @throws IOException */ private void saveKeys(String fileName,BigInteger mod,BigInteger exp) throws IOException{ FileOutputStream fos = null; ObjectOutputStream oos = null; try { System.out.println("Generating "+fileName + "..."); fos = new FileOutputStream(fileName); oos = new ObjectOutputStream(new BufferedOutputStream(fos)); oos.writeObject(mod); oos.writeObject(exp); System.out.println(fileName + " generated successfully"); } catch (Exception e) { e.printStackTrace(); } finally{ if(oos != null){ oos.close(); if(fos != null){ fos.close(); } } } } /** * Encrypt Data * @param data * @throws IOException */ private byte[] encryptData(String data) throws IOException { System.out.println("\n----------------ENCRYPTION STARTED------------"); System.out.println("Data Before Encryption :" + data); byte[] dataToEncrypt = data.getBytes(); byte[] encryptedData = null; try { PublicKey pubKey = readPublicKeyFromFile(PUBLIC_KEY_FILE); Cipher cipher = Cipher.getInstance("RSA"); cipher.init(Cipher.ENCRYPT_MODE, pubKey); encryptedData = cipher.doFinal(dataToEncrypt); System.out.println("Encryted Data: " + encryptedData); } catch (Exception e) { e.printStackTrace(); } System.out.println("----------------ENCRYPTION COMPLETED------------"); return encryptedData; } /** * Encrypt Data * @param data * @throws IOException */ private void decryptData(byte[] data) throws IOException { System.out.println("\n----------------DECRYPTION STARTED------------"); byte[] descryptedData = null; try { PrivateKey privateKey = readPrivateKeyFromFile(PRIVATE_KEY_FILE); Cipher cipher = Cipher.getInstance("RSA"); cipher.init(Cipher.DECRYPT_MODE, privateKey); descryptedData = cipher.doFinal(data); System.out.println("Decrypted Data: " + new String(descryptedData)); } catch (Exception e) { e.printStackTrace(); } System.out.println("----------------DECRYPTION COMPLETED------------"); } /** * read Public Key From File * @param fileName * @return PublicKey * @throws IOException */ public PublicKey readPublicKeyFromFile(String fileName) throws IOException{ FileInputStream fis = null; ObjectInputStream ois = null; try { fis = new FileInputStream(new File(fileName)); ois = new ObjectInputStream(fis); BigInteger modulus = (BigInteger) ois.readObject(); BigInteger exponent = (BigInteger) ois.readObject(); //Get Public Key RSAPublicKeySpec rsaPublicKeySpec = new RSAPublicKeySpec(modulus, exponent); KeyFactory fact = KeyFactory.getInstance("RSA"); PublicKey publicKey = fact.generatePublic(rsaPublicKeySpec); return publicKey; } catch (Exception e) { e.printStackTrace(); } finally{ if(ois != null){ ois.close(); if(fis != null){ fis.close(); } } } return null; } /** * read Public Key From File * @param fileName * @return * @throws IOException */ public PrivateKey readPrivateKeyFromFile(String fileName) throws IOException{ FileInputStream fis = null; ObjectInputStream ois = null; try { fis = new FileInputStream(new File(fileName)); ois = new ObjectInputStream(fis); BigInteger modulus = (BigInteger) ois.readObject(); BigInteger exponent = (BigInteger) ois.readObject(); //Get Private Key RSAPrivateKeySpec rsaPrivateKeySpec = new RSAPrivateKeySpec(modulus, exponent); KeyFactory fact = KeyFactory.getInstance("RSA"); PrivateKey privateKey = fact.generatePrivate(rsaPrivateKeySpec); return privateKey; } catch (Exception e) { e.printStackTrace(); } finally{ if(ois != null){ ois.close(); if(fis != null){ fis.close(); } } } return null; } }