AES Encryption objective c counter part for java code - ios

Question

I would like to convert the below Java aes encryption to objective c. Anyone who has knowledge in both Java and Objective C please help. Any help will be greatly appreciated. Can anyone help by providing the details of encryption method used?
import java.io.IOException;
import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.SecretKey;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
public class Crypto {
public static final String TAG = Crypto.class.getSimpleName();
// Replace me with a 16-byte key, share between Java and C#
private static Cipher aesCipher;
private static SecretKey secretKey;
private static IvParameterSpec ivParameterSpec;
private static String CIPHER_TRANSFORMATION = "AES/CBC/PKCS5Padding";
private static String CIPHER_ALGORITHM = "AES";
private static byte[] rawSecretKey = {0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00};
// private static String MESSAGEDIGEST_ALGORITHM = "MD5";
private static String MESSAGEDIGEST_ALGORITHM = "SHA-256";
public Crypto(String passphrase) {
byte[] passwordKey = encodeDigest(passphrase);
try {
aesCipher = Cipher.getInstance(CIPHER_TRANSFORMATION);
} catch (NoSuchAlgorithmException e) {
Log.e(TAG, "No such algorithm " + CIPHER_ALGORITHM, e);
} catch (NoSuchPaddingException e) {
Log.e(TAG, "No such padding PKCS5", e);
}
secretKey = new SecretKeySpec(passwordKey, CIPHER_ALGORITHM);
ivParameterSpec = new IvParameterSpec(rawSecretKey);
}
public byte[] decrypt(byte[] clearData) {
try {
aesCipher.init(Cipher.DECRYPT_MODE, secretKey);
} catch (InvalidKeyException e) {
e.printStackTrace();
}
byte[] decryptedData;
try {
decryptedData = aesCipher.doFinal(clearData);
} catch (IllegalBlockSizeException e) {
e.printStackTrace();
return null;
} catch (BadPaddingException e) {
e.printStackTrace();
return null;
}
return decryptedData;
}
public String decryptAsBase64(byte[] clearData) throws IOException {
byte[] decryptedData = decrypt(clearData);
return new String(Base64New.decode(decryptedData));
}
public String encryptAsBase64(byte[] clearData) {
byte[] encryptedData = encrypt(clearData);
return Base64New.encodeBytes(encryptedData);
}
public byte[] encrypt(byte[] clearData) {
try {
aesCipher.init(Cipher.ENCRYPT_MODE, secretKey, ivParameterSpec);
} catch (InvalidKeyException e) {
Log.e(TAG, "Invalid key", e);
return null;
} catch (InvalidAlgorithmParameterException e) {
Log.e(TAG, "Invalid algorithm " + CIPHER_ALGORITHM, e);
return null;
}
byte[] encryptedData;
try {
encryptedData = aesCipher.doFinal(clearData);
} catch (IllegalBlockSizeException e) {
Log.e(TAG, "Illegal block size", e);
return null;
} catch (BadPaddingException e) {
Log.e(TAG, "Bad padding", e);
return null;
}
return encryptedData;
}
private byte[] encodeDigest(String text) {
MessageDigest digest;
try {
digest = MessageDigest.getInstance(MESSAGEDIGEST_ALGORITHM);
return digest.digest(text.getBytes());
} catch (NoSuchAlgorithmException e) {
Log.e(TAG, "No such algorithm " + MESSAGEDIGEST_ALGORITHM, e);
}
return null;
}
}

Answer 1

Here are the details of encryption method used:
The encryption is AES in CBC mode with PKCS#5 padding (PKCS#7 padding is the same here).
The CBC mode has an iv as input, the iv is the rawSecretKey which is all 0 bytes (not a best practice).
The encryption passwordKey is derived from the secretKey using SHA-256 (not a best practice).
Additionally there are methods to add and remove Base64 encoding.