How to encrypt & decrypt large video file

Question

I would like to store video files in storage that can be accessed only my application. outside the user should not be able to access his video. I tried Encryption & Decryption but the video file is too large (1GB) it takes a lot of time.

Do you have any Idea guys how can I do?

Please find below my Encryption & Decryption Code :

 private File sdCardRoot;
private ProgressBar progressBar;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    sdCardRoot = Environment.getExternalStorageDirectory();
    Button encrypt = findViewById(R.id.zip);
    Button dencrypt = findViewById(R.id.unzip);
    progressBar = findViewById(R.id.progress);

    encrypt.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            progressBar.setVisibility(View.VISIBLE);
            try {
                Log.e("file", "try");
                encryption();
            } catch (Exception e) {
                Log.e("file", "catch" + String.valueOf(e));

                e.printStackTrace();
            }
        }
    });

    dencrypt.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            progressBar.setVisibility(View.VISIBLE);
            try {
                dcryption();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    });

}

private void dcryption() throws Exception {
    progressBar.setVisibility(View.VISIBLE);
    String password = "javapapers";

    // reading the salt
    // user should have secure mechanism to transfer the
    // salt, iv and password to the recipient
    File fileSalt = new File(sdCardRoot, "/salt.enc");
    FileInputStream saltFis = new FileInputStream(fileSalt);
    byte[] salt = new byte[8];
    saltFis.read(salt);
    saltFis.close();

    // reading the iv
    File fileIv = new File(sdCardRoot, "/iv.enc");
    FileInputStream ivFis = new FileInputStream(fileIv);
    byte[] iv = new byte[16];
    ivFis.read(iv);
    ivFis.close();

    SecretKeyFactory factory = SecretKeyFactory
            .getInstance("PBKDF2WithHmacSHA1");
    KeySpec keySpec = new PBEKeySpec(password.toCharArray(), salt, 65536,
            256);
    SecretKey tmp = factory.generateSecret(keySpec);
    SecretKey secret = new SecretKeySpec(tmp.getEncoded(), "AES");

    // file decryption
    Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
    cipher.init(Cipher.DECRYPT_MODE, secret, new IvParameterSpec(iv));
    File oldFile = new File(sdCardRoot, "/wp.mp4");
    File oldFile1 = new File(sdCardRoot, "/w.des");
    FileInputStream fis = new FileInputStream(oldFile1);
    FileOutputStream fos = new FileOutputStream(oldFile);
    byte[] in = new byte[64];
    int read;
    while ((read = fis.read(in)) != -1) {
        byte[] output = cipher.update(in, 0, read);
        if (output != null)
            fos.write(output);
    }

    byte[] output = cipher.doFinal();
    if (output != null) {
        fos.write(output);
        fis.close();
        fos.flush();
        fos.close();
    }
    if (fileIv.exists() && fileSalt.exists() && oldFile1.exists()) {
        fileIv.delete();
        fileSalt.delete();
        oldFile1.delete();
    }
    progressBar.setVisibility(View.GONE);
    System.out.println("File Decrypted.");
}


private void encryption() throws Exception {

    File oldFile = new File(sdCardRoot, "/w.mp4");
    File oldFile1 = new File(sdCardRoot, "/w.des");

    Log.e("file", String.valueOf(oldFile));
    FileInputStream inFile = new FileInputStream(oldFile);
    Log.e("file", String.valueOf(inFile));
    // encrypted file
    FileOutputStream outFile = new FileOutputStream(oldFile1);
    Log.e("file", String.valueOf(outFile));

    // password to encrypt the file
    String password = "javapapers";

    // password, iv and salt should be transferred to the other end
    // in a secure manner

    // salt is used for encoding
    // writing it to a file
    // salt should be transferred to the recipient securely
    // for decryption
    byte[] salt = new byte[8];
    SecureRandom secureRandom = new SecureRandom();
    secureRandom.nextBytes(salt);
    Log.e("file", "a");
    File fileSalt = new File(sdCardRoot, "/salt.enc");

    FileOutputStream saltOutFile = new FileOutputStream(fileSalt);
    Log.e("file", "b");

    saltOutFile.write(salt);
    saltOutFile.close();

    SecretKeyFactory factory = SecretKeyFactory
            .getInstance("PBKDF2WithHmacSHA1");
    KeySpec keySpec = new PBEKeySpec(password.toCharArray(), salt, 65536,
            256);
    SecretKey secretKey = factory.generateSecret(keySpec);
    SecretKey secret = new SecretKeySpec(secretKey.getEncoded(), "AES");

    //
    Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
    cipher.init(Cipher.ENCRYPT_MODE, secret);
    AlgorithmParameters params = cipher.getParameters();

    // iv adds randomness to the text and just makes the mechanism more
    // secure
    // used while initializing the cipher
    // file to store the iv
    Log.e("file", "c");
    File fileIv = new File(sdCardRoot, "/iv.enc");

    FileOutputStream ivOutFile = new FileOutputStream(fileIv);
    Log.e("file", "d");
    byte[] iv = params.getParameterSpec(IvParameterSpec.class).getIV();
    ivOutFile.write(iv);
    ivOutFile.close();

    //file encryption
    byte[] input = new byte[64];
    int bytesRead;

    while ((bytesRead = inFile.read(input)) != -1) {
        byte[] output = cipher.update(input, 0, bytesRead);
        if (output != null)
            outFile.write(output);
    }

    byte[] output = cipher.doFinal();
    if (output != null)
        outFile.write(output);

    inFile.close();
    outFile.flush();
    outFile.close();

    if (oldFile.exists()) {
        oldFile.delete();
    }

    System.out.println("File Encrypted.");

}

You should check here. https://stackoverflow.com/questions/4275311/how-to-encrypt-and-decrypt-file-in-android/8041442 — mrtcnkryln, Jan 29 '20 at 05:44

score 2 · Accepted Answer · answered Jan 29 '20 at 06:01

Use Below Code:

import java.io.File;
import java.io.RandomAccessFile;

public class VideoCrypt {
    public static final int REVERSE_BYTE_COUNT = 1024;

    public static boolean decrypt(String path) {
        try {
            if (path == null) return false;
            File source = new File(path);
            int byteToReverse = source.length() < REVERSE_BYTE_COUNT ? ((int) source.length()) : REVERSE_BYTE_COUNT;
            RandomAccessFile f = new RandomAccessFile(source, "rw");
            f.seek(0);
            byte b[] = new byte[byteToReverse];
            f.read(b);
            f.seek(0);
            reverseBytes(b);
            f.write(b);
            f.seek(0);
            b = new byte[byteToReverse];
            f.read(b);
            f.close();
            return true;
        } catch (Exception e) {
            return false;
        }
    }

    public static boolean encrypt(String path) {
        try {
            if (path == null) return false;
            File source = new File(path);
            RandomAccessFile f = new RandomAccessFile(source, "rw");
            f.seek(0);
            int byteToReverse = source.length() < REVERSE_BYTE_COUNT ? ((int) source.length()) : REVERSE_BYTE_COUNT;
            byte b[] = new byte[byteToReverse];
            f.read(b);
            f.seek(0);
            reverseBytes(b);
            f.write(b);
            f.seek(0);
            b = new byte[byteToReverse];
            f.read(b);
            f.close();
            return true;
        } catch (Exception e) {
            return false;
        }
    }

    private static void reverseBytes(byte[] array) {
        if (array == null) return;
        int i = 0;
        int j = array.length - 1;
        byte tmp;
        while (j > i) {
            tmp = array[j];
            array[j] = array[i];
            array[i] = tmp;
            j--;
            i++;
        }
    }
}

score 0 · Answer 2 · answered Jan 29 '20 at 06:28

0

File types are identified by file extension and file magic. If you want to skip encrypting the file you can edit the file header by changing its magic so that programs can't recognize the type. A "magic" is a few bytes at the start of the file that define its type.

answered Jan 29 '20 at 06:28

CausingUnderflowsEverywhere

1,908
13
33

1

can you share more in dept of how to edit the first few bytes of a file please? – zernzern1993 May 19 '20 at 08:27
Good idea, Ill add some when I get a chance. – CausingUnderflowsEverywhere Jun 01 '20 at 20:22
In case anyone needs it, this worked for me: https://stackoverflow.com/questions/4576388/changing-a-specific-byte-in-a-file – nivla360 Jul 19 '20 at 03:08

How to encrypt & decrypt large video file

2 Answers2