Android AES Encryption / Decryption

Question

I managed to encode a function to encrypt / decrypt files. But its very slow, especially as the file size increases. for example, a few MB audio / vidoe file

I went through almost the entire post to improve it, and tried to change the algortma. Please help me if there are any changes that can help me improve my performance.

public class DataEncryptDecrypt {
public Cipher encryptcipher, decryptCipher;
int blockSize = 16;
String TAG = "DataEncryptDecrypt";
private static final String RANDOM_ALGORITHM = "SHA1PRNG";

public DataEncryptDecrypt(String passwd) {
    final String CIPHERMODEPADDING = "AES/CBC/PKCS5Padding";
    //AES/CBC/PKCS7Padding
    char[] humanPassphrase = passwd.toCharArray();
    byte[] salt = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0xA, 0xB, 0xC, 0xD, 0xE,
            0xF }; // must save this!
    //salt =generateSalt();
    final int HASH_ITERATIONS = 100;
    final int KEY_LENGTH = 128; //256
    PBEKeySpec mykeyspec = new PBEKeySpec(humanPassphrase, salt,
            HASH_ITERATIONS, KEY_LENGTH);
//  final String KEY_GENERATION_ALG = "PBEWITHSHAANDTWOFISH-CBC";
    final String KEY_GENERATION_ALG="PBEWithMD5And128BitAES-CBC-OpenSSL";
    SecretKey sk;
    try {
        encryptcipher = Cipher.getInstance(CIPHERMODEPADDING);
        SecretKeyFactory keyfactory = SecretKeyFactory
                .getInstance(KEY_GENERATION_ALG);
        sk = keyfactory.generateSecret(mykeyspec);

        // step 1 - get an instance of the cipher, specifying the mode and
        // padding

        byte[] iv = { 0xA, 1, 0xB, 5, 4, 0xF, 7, 9, 0x17, 3, 1, 6, 8, 0xC,
                0xD, 91 }; // must save this
        //iv= generateIv();
        IvParameterSpec IV = new IvParameterSpec(iv);
        encryptcipher = Cipher.getInstance(CIPHERMODEPADDING);
        decryptCipher = Cipher.getInstance(CIPHERMODEPADDING);

        // step 2 - initialize the cipher
        encryptcipher.init(Cipher.ENCRYPT_MODE, sk, IV);
        decryptCipher.init(Cipher.DECRYPT_MODE, sk, IV);

    } catch (NoSuchAlgorithmException nsae) {
        Log.e("AESdemo",
                "no key factory support for PBEWITHSHAANDTWOFISH-CBC");
    } catch (InvalidKeySpecException ikse) {
        Log.e("AESdemo", "invalid key spec for PBKDF2");
    } catch (Exception ex) {

    }
}

public String encryptData(String inputFileName) {
    String outFilename = null;
    File inputFile = new File(inputFileName);
    try {

        // step 3 - not needed, as we have all the blocks on hand

        // step 4 - call doFinal()

         outFilename = ".".concat(CommonUtils.getHash(inputFile.getName()));
        InputStream fis;
        OutputStream fos;
        fis = new BufferedInputStream(new FileInputStream(inputFileName));

        fos = new BufferedOutputStream(new FileOutputStream(
                inputFile.getParent() + "/" + outFilename));
        Log.i(TAG, "Output path:" + inputFile.getParent() + "/" + outFilename);
        byte[] buffer = new byte[blockSize];
        int noBytes = 0;
        byte[] cipherBlock = new byte[encryptcipher
                .getOutputSize(buffer.length)];
        int cipherBytes;
        while ((noBytes = fis.read(buffer)) != -1) {
            cipherBytes = encryptcipher.update(buffer, 0, noBytes,
                    cipherBlock);
            fos.write(cipherBlock, 0, cipherBytes);
        }
        // always call doFinal
        cipherBytes = encryptcipher.doFinal(cipherBlock, 0);
        fos.write(cipherBlock, 0, cipherBytes);

        // close the files
        fos.close();
        fis.close();
        Log.i("encrpty", "done");
        inputFile.delete();
    }

    catch (Exception ex) {
        ex.printStackTrace();
    }
    return inputFile.getParent() + "/" + outFilename;
}

I kept in the comments the other algos that I tried but did not see any difference. Thank you very much for your help

Answer 1

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