title: BadPaddingException When Decrypting Separately using AES in Java
body: <p>I'm doing an encryption/decryption using AES. I'm trying to encrypt a text, then decrypt it separately later. </p>
  
  <p>My AESEncrypt.java is:</p>
  
  <pre><code>import javax.crypto.Cipher;
  import javax.crypto.SecretKey;
  import javax.crypto.SecretKeyFactory;
  import javax.crypto.spec.IvParameterSpec;
  import javax.crypto.spec.PBEKeySpec;
  import javax.crypto.spec.SecretKeySpec;
  import java.security.spec.KeySpec;
  import org.apache.commons.codec.binary.Base64;
  
  public class AESEncrypt {
      private static final byte[] SALT = {(byte) 0xA9, (byte) 0x9B, (byte) 0xC8, (byte) 0x32, (byte) 0x56, (byte) 0x35, (byte) 0xE3, (byte) 0x03};
      private static final int ITERATION_COUNT = 65536;
      private static final int KEY_LENGTH = 256;
      private Cipher eCipher;
      private Cipher dCipher;
  
      AESEncrypt(String passPhrase) throws Exception {
          SecretKeyFactory secretKeyFactory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA1");
          KeySpec keySpec = new PBEKeySpec(passPhrase.toCharArray(), SALT, ITERATION_COUNT, KEY_LENGTH);
          SecretKey secretKeyTemp = secretKeyFactory.generateSecret(keySpec);
          SecretKey secretKey = new SecretKeySpec(secretKeyTemp.getEncoded(), "AES");
  
          eCipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
          eCipher.init(Cipher.ENCRYPT_MODE, secretKey);
  
          dCipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
          byte[] iv = eCipher.getParameters().getParameterSpec(IvParameterSpec.class).getIV();
          dCipher.init(Cipher.DECRYPT_MODE, secretKey, new IvParameterSpec(iv));
      }
  
      public String encrypt(String encrypt) throws Exception {
          byte[] bytes = encrypt.getBytes("UTF8");
          byte[] encrypted = encrypt(bytes);
          return new String(Base64.encodeBase64(encrypted));
      }
  
      public byte[] encrypt(byte[] plain) throws Exception {
          return eCipher.doFinal(plain);
      }
  
      public static void main(String[] args) throws Exception {
          String passphrase = "PASSWORDPASSPHRASE";
          String password = "password123";    
          AESEncrypt aesEncrypt = new AESEncrypt(passphrase); 
          String encryptedPassword = aesEncrypt.encrypt(password);
          System.out.println("encryptedPassword = " + encryptedPassword);
      }
  }
  </code></pre>
  
  <p>After running the AESEncrypt code above, the result is:</p>
  
  <pre><code>encryptedPassword = aUkbhjFebZ9VjJ44yptlBA==
  </code></pre>
  
  <p>So, now in my AESDecrypt.java, I'm using that encryptedPassword string to be decrypted:</p>
  
  <pre><code>import javax.crypto.Cipher;
  import javax.crypto.SecretKey;
  import javax.crypto.SecretKeyFactory;
  import javax.crypto.spec.IvParameterSpec;
  import javax.crypto.spec.PBEKeySpec;
  import javax.crypto.spec.SecretKeySpec;
  import java.security.spec.KeySpec;
  import org.apache.commons.codec.binary.Base64;
  
  public class AESDecrypt {
      private static final byte[] SALT = {(byte) 0xA9, (byte) 0x9B, (byte) 0xC8, (byte) 0x32, (byte) 0x56, (byte) 0x35, (byte) 0xE3, (byte) 0x03};
      private static final int ITERATION_COUNT = 65536;
      private static final int KEY_LENGTH = 256;
      private Cipher eCipher;
      private Cipher dCipher;
  
      AESDecrypt(String passPhrase) throws Exception {
          SecretKeyFactory secretKeyFactory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA1");
          KeySpec keySpec = new PBEKeySpec(passPhrase.toCharArray(), SALT, ITERATION_COUNT, KEY_LENGTH);
          SecretKey secretKeyTemp = secretKeyFactory.generateSecret(keySpec);
          SecretKey secretKey = new SecretKeySpec(secretKeyTemp.getEncoded(), "AES");
  
          eCipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
          eCipher.init(Cipher.ENCRYPT_MODE, secretKey);
  
          dCipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
          byte[] iv = eCipher.getParameters().getParameterSpec(IvParameterSpec.class).getIV();
          dCipher.init(Cipher.DECRYPT_MODE, secretKey, new IvParameterSpec(iv));
      }
  
      public String decrypt(String encrypt) throws Exception {
          byte[] bytes = Base64.decodeBase64(encrypt);
          byte[] decrypted = decrypt(bytes);
          return new String(decrypted, "UTF8");
      }
  
      public byte[] decrypt(byte[] encrypt) throws Exception {
          return dCipher.doFinal(encrypt);
      }
  
      public static void main(String[] args) throws Exception {
          String passphrase = "PASSWORDPASSPHRASE";
          String encryptedPassword = "aUkbhjFebZ9VjJ44yptlBA==";        
          AESDecrypt aesDecrypt = new AESDecrypt(passphrase);
          String decryptedPassword = aesDecrypt.decrypt(encryptedPassword);
          System.out.println("decryptedPasswpord = " + decryptedPassword);
      }
  }
  </code></pre>
  
  <p>When running the AESDecrypt code, an error is returned:</p>
  
  <pre><code>Exception in thread "main" javax.crypto.BadPaddingException: Given final block not properly padded
      at com.sun.crypto.provider.SunJCE_f.b(DashoA13*..)
      at com.sun.crypto.provider.SunJCE_f.b(DashoA13*..)
      at com.sun.crypto.provider.AESCipher.engineDoFinal(DashoA13*..)
      at javax.crypto.Cipher.doFinal(DashoA13*..)
      at AESDecrypt.decrypt(AESDecrypt.java:41)
      at AESDecrypt.decrypt(AESDecrypt.java:35)
      at AESDecrypt.main(AESDecrypt.java:50)
  </code></pre>
  
  <p>Why do I get an error? Can anyone help and advise, please? Thank you very much!</p>