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Java SE




Encrypt files




package testexample; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import javax.crypto.Cipher; import javax.crypto.CipherInputStream; import javax.crypto.CipherOutputStream; import javax.crypto.SecretKey; import javax.crypto.SecretKeyFactory; import javax.crypto.spec.DESKeySpec; public class Testexample { public static void main(String[] args) { try { String key = "squirrel123"; // needs to be at least 8 characters for DES FileInputStream fis = new FileInputStream("original.txt"); FileOutputStream fos = new FileOutputStream("encrypted.txt"); encrypt(key, fis, fos); FileInputStream fis2 = new FileInputStream("encrypted.txt"); FileOutputStream fos2 = new FileOutputStream("decrypted.txt"); decrypt(key, fis2, fos2); } catch (Throwable e) { e.printStackTrace(); } } public static void encrypt(String key, InputStream is, OutputStream os) throws Throwable { encryptOrDecrypt(key, Cipher.ENCRYPT_MODE, is, os); } public static void decrypt(String key, InputStream is, OutputStream os) throws Throwable { encryptOrDecrypt(key, Cipher.DECRYPT_MODE, is, os); } public static void encryptOrDecrypt(String key, int mode, InputStream is, OutputStream os) throws Throwable { DESKeySpec dks = new DESKeySpec(key.getBytes()); SecretKeyFactory skf = SecretKeyFactory.getInstance("DES"); SecretKey desKey = skf.generateSecret(dks); Cipher cipher = Cipher.getInstance("DES"); // DES/ECB/PKCS5Padding for SunJCE if (mode == Cipher.ENCRYPT_MODE) { cipher.init(Cipher.ENCRYPT_MODE, desKey); CipherInputStream cis = new CipherInputStream(is, cipher); doCopy(cis, os); } else if (mode == Cipher.DECRYPT_MODE) { cipher.init(Cipher.DECRYPT_MODE, desKey); CipherOutputStream cos = new CipherOutputStream(os, cipher); doCopy(is, cos); } } public static void doCopy(InputStream is, OutputStream os) throws IOException { byte[] bytes = new byte[64]; int numBytes; while ((numBytes = is.read(bytes)) != -1) { os.write(bytes, 0, numBytes); } os.flush(); os.close(); is.close(); } }
 


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