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Is there any way to encrypt SQLite Database on External SD-Card?

I'm creating an app which has its predefined SQLite database on external SD-Card with some videos | images & PDFs in SD-Card folder.
I have heard of encrypting database using "PRAGMA". But I think this isn't safe.
Can I encrypt the file and database using a key and reuse this SD-Card in another phone having my App installed?
Is there any other alternative solution available for reference?
Encrypting Database :
class MyHelper extends SQLiteOpenHelper {
void onConfigure(SQLiteDatabase db){
db.execSQL("PRAGMA key = 'secretkey'");
}
}
Encryption Helper Functions :
public static byte[] generateKey(String password) throws Exception
{
byte[] keyStart = password.getBytes("UTF-8");
KeyGenerator kgen = KeyGenerator.getInstance("AES");
SecureRandom sr = SecureRandom.getInstance("SHA1PRNG", "Crypto");
sr.setSeed(keyStart);
kgen.init(128, sr);
SecretKey skey = kgen.generateKey();
return skey.getEncoded();
}
public static byte[] encodeFile(byte[] key, byte[] fileData) throws Exception
{
SecretKeySpec skeySpec = new SecretKeySpec(key, "AES");
Cipher cipher = Cipher.getInstance("AES");
cipher.init(Cipher.ENCRYPT_MODE, skeySpec);
byte[] encrypted = cipher.doFinal(fileData);
return encrypted;
}
public static byte[] decodeFile(byte[] key, byte[] fileData) throws Exception
{
SecretKeySpec skeySpec = new SecretKeySpec(key, "AES");
Cipher cipher = Cipher.getInstance("AES");
cipher.init(Cipher.DECRYPT_MODE, skeySpec);
byte[] decrypted = cipher.doFinal(fileData);
return decrypted;
}
To save encrypted file to SD-Card :
File file = new File(Environment.getExternalStorageDirectory() + File.separator + "your_folder_on_sd", "file_name");
BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(file));
byte[] yourKey = generateKey("password");
byte[] filesBytes = encodeFile(yourKey, yourByteArrayContainigDataToEncrypt);
bos.write(fileBytes);
bos.flush();
bos.close();
To Decode file :
byte[] yourKey = generateKey("password");
byte[] decodedData = decodeFile(yourKey, bytesOfYourFile);

Java Android - Encrypt/Decrypt file contents

So at the moment I'm trying to write some encrypted text to a file and then be able to read that back in, decrypt it and display it to the user. I'm currently using AES-256 with PBKDF2 password derivation as I'd like to be able to use a user's password to encrypt/decrypt the files. The files are simple text files. The code I am currently using to encrypt some text and save it to a file is below. As far as I can tell, from having a look using adb, this works correctly.
FileOutputStream out = new FileOutputStream(mypath);
String defaultMessage = "Empty File";
int iterationCount = 1000;
int keyLength = 256;
int saltLength = keyLength / 8;
SecureRandom randomGenerator = new SecureRandom();
byte[] salt = new byte[saltLength];
randomGenerator.nextBytes(salt);
KeySpec keySpec = new PBEKeySpec(submittedPassword.toCharArray(), salt, iterationCount, keyLength);
SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA1");
byte[] keyBytes = keyFactory.generateSecret(keySpec).getEncoded();
SecretKey key = new SecretKeySpec(keyBytes, "AES");
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
byte[] iv = new byte[cipher.getBlockSize()];
randomGenerator.nextBytes(iv);
IvParameterSpec ivParams = new IvParameterSpec(iv);
cipher.init(Cipher.ENCRYPT_MODE, key, ivParams);
byte[] ciphertext = cipher.doFinal(defaultMessage.getBytes("UTF-8"));
String finalMessage = ciphertext.toString() + "]" + iv.toString() + "]" + salt.toString();
out.write(finalMessage.getBytes());
out.close();
P.S The above is within a Try/Except.
The code below is what I'm currently trying to use to read in the file and then decrypt it, however, when I try to display the decrypted contents via the test view at the end, it does not show up.
FileInputStream fileInputStream = new FileInputStream(mypath);
InputStreamReader inputStreamReader = new InputStreamReader(fileInputStream);
BufferedReader bufferedReader = new BufferedReader(inputStreamReader);
StringBuffer stringBuffer = new StringBuffer();
while ((fileContents = bufferedReader.readLine()) != null) {
stringBuffer.append(fileContents + "\n");
}
String fileContentsString = stringBuffer.toString();
String[] fileContentsList = fileContentsString.split("]");
byte[] cipherText = fileContentsList[0].getBytes();
Toast.makeText(getApplicationContext(), fileContentsList[0], Toast.LENGTH_LONG).show();
byte[] iv = fileContentsList[1].getBytes();
byte[] salt = fileContentsList[2].getBytes();
KeySpec keySpec = new PBEKeySpec(submittedPassword.toCharArray(), salt, 1000, 256);
SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA1");
byte[] keyBytes = keyFactory.generateSecret(keySpec).getEncoded();
SecretKey key = new SecretKeySpec(keyBytes, "AES");
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
IvParameterSpec ivParams = new IvParameterSpec(iv);
cipher.init(Cipher.DECRYPT_MODE, key, ivParams);
byte[] plaintext = cipher.doFinal(cipherText);
String plainrStr = new String(plaintext , "UTF-8");
textEdit.setText(plainrStr);
Hopefully someone can provide me with some assistance here. Again, the second code segment is within a Try/Except statement.

You have multiple problems with your code.
Encryption
This code
String finalMessage = ciphertext.toString() + "]" + iv.toString() + "]" + salt.toString();
does not produce a ciphertext. See here: Java: Syntax and meaning behind "[B#1ef9157"? Binary/Address?
The IV and salt have fixed sizes, so they can be placed in front of the ciphertext. After you've written the whole ciphertext, you need to use something like Base64 or Hex in order to get a String. Modern ciphers like AES produce ciphertexts that can contain bytes of any value which don't always constitute valid character encodings such as UTF-8. Strings are no containers for arbitrary byte[] contents.
ByteArrayOutputStream baos = new ByteArrayOutputStream();
baos.write(iv);
baos.write(salt);
baos.write(ciphertext);
String finalMessage = Base64.encodeToString(baos.toByteArray(), Base64.DEFAULT);
But you don't need that at all, because you can directly write your ciphertext into the file:
out.write(iv);
out.write(salt);
out.write(ciphertext);
Decryption
Don't use InputStreamReader, a BufferedReader and a StringBuffer for binary data. Otherwise, you'll corrupt your binary ciphertext.
You only need this:
byte[] iv = new byte[16];
byte[] salt = new byte[32];
byte[] ctChunk = new byte[8192]; // not for whole ciphertext, just a buffer
if (16 != fileInputStream.read(iv) || 32 != fileInputStream.read(salt)) {
throw new Exception("IV or salt too short");
}
KeySpec keySpec = new PBEKeySpec(submittedPassword.toCharArray(), salt, 1000, 256);
SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA1");
byte[] keyBytes = keyFactory.generateSecret(keySpec).getEncoded();
SecretKey key = new SecretKeySpec(keyBytes, "AES");
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
IvParameterSpec ivParams = new IvParameterSpec(iv);
cipher.init(Cipher.DECRYPT_MODE, key, ivParams);
int read;
ByteArrayOutputStream ctBaos = new ByteArrayOutputStream();
while((read = fileInputStream.read(ctChunk)) > 0) {
ctBaos.write(cipher.update(cipherText, 0, read));
}
ctBaos.write(cipher.doFinal());
String plainrStr = new String(ctBaos.toByteArray(), "UTF-8");
textEdit.setText(plainrStr);
This handles randomization properly but doesn't provide integrity. If you want to detect (malicious) manipulations of your ciphertexts (and generally you'll want that to prevent some attacks), you'd need to use an authenticated mode like GCM or EAX, or employ an encrypt-then-MAC scheme with a strong MAC like HMAC-SHA256.
Use a library like tozny/java-aes-crypto in order to use good defaults.

How to write some encrypted text to a file and then be able to read that back in?
public static byte[] generateKey(String password) throws Exception
{
byte[] keyStart = password.getBytes("UTF-8");
KeyGenerator kgen = KeyGenerator.getInstance("AES");
SecureRandom sr = SecureRandom.getInstance("SHA1PRNG", "Crypto");
sr.setSeed(keyStart);
kgen.init(128, sr);
SecretKey skey = kgen.generateKey();
return skey.getEncoded();
}
public static byte[] encodeFile(byte[] key, byte[] fileData) throws Exception
{
SecretKeySpec skeySpec = new SecretKeySpec(key, "AES");
Cipher cipher = Cipher.getInstance("AES");
cipher.init(Cipher.ENCRYPT_MODE, skeySpec);
byte[] encrypted = cipher.doFinal(fileData);
return encrypted;
}
public static byte[] decodeFile(byte[] key, byte[] fileData) throws Exception
{
SecretKeySpec skeySpec = new SecretKeySpec(key, "AES");
Cipher cipher = Cipher.getInstance("AES");
cipher.init(Cipher.DECRYPT_MODE, skeySpec);
byte[] decrypted = cipher.doFinal(fileData);
return decrypted;
}
To save a encrypted file to sd do:
File file = new File(Environment.getExternalStorageDirectory() + File.separator + "your_folder_on_sd", "file_name");
BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(file));
byte[] yourKey = generateKey("password");
byte[] filesBytes = encodeFile(yourKey, yourByteArrayContainigDataToEncrypt);
bos.write(fileBytes);
bos.flush();
bos.close();
To decode a file use:
byte[] yourKey = generateKey("password");
byte[] decodedData = decodeFile(yourKey, bytesOfYourFile);
For reading in a file to a byte Array there a different way out there. A Example: http://examples.javacodegeeks.com/core-java/io/fileinputstream/read-file-in-byte-array-with-fileinputstream/

Trying to remove the last 16 bytes that I appended onto the byte[] (which is the IV) then decrypt

Here is my encryption class:
public static void encrypt(byte[] file, String password, String fileName, String dir) throws Exception {
SecureRandom r = new SecureRandom();
//128 bit IV generated for each file
byte[] iv = new byte[IV_LENGTH];
r.nextBytes(iv);
IvParameterSpec ivspec = new IvParameterSpec(iv);
SecretKeySpec keySpec = new SecretKeySpec(password.getBytes(), "AES");
Cipher cipher = Cipher.getInstance("AES/CBC/NoPadding");
cipher.init(Cipher.ENCRYPT_MODE, keySpec, ivspec);
FileOutputStream fos = new FileOutputStream(dir + fileName);
fos.write(iv);
CipherOutputStream cos = new CipherOutputStream(fos, cipher);
// Have to append IV --------
cos.write(file);
fos.flush();
cos.flush();
cos.close();
fos.close();
}
This is my Decryption method:
public static void decrypt(byte[] file, String password, String fileName, String dir) throws Exception
{
// gets the IV
int ivIndex = file.length - 16;
byte[] truncatedFile = Arrays.copyOfRange(file, 0, file.length - 16);
SecretKeySpec keySpec = new SecretKeySpec(password.getBytes(), "AES");
Cipher cipher = Cipher.getInstance("AES/CBC/NoPadding");
cipher.init(Cipher.DECRYPT_MODE, keySpec, new IvParameterSpec(truncatedFile, ivIndex, 16));
//IvParameterSpec ivspec = new IvParameterSpec(iv);
//
//cipher.init(Cipher.DECRYPT_MODE, keySpec, ivspec);
FileOutputStream fos = new FileOutputStream(dir + fileName);
CipherOutputStream cos = new CipherOutputStream(fos, cipher);
cos.write(file);
fos.flush();
cos.flush();
cos.close();
fos.close();
}
}
As you can see I generated a 16 byte long IV that I have appended to the end of the encrypted file. This is so that I pull off the IV for decryption as well as every filing have a unique IV. I am currently getting the error:
java.lang.IllegalArgumentException: IV buffer too short for given offset/length combination
Aside from the problem generating the error, is my logic correct? will this work?

I generated a 16 byte long IV that I have appended to the end of the encrypted file.
No you didn't. You pre-pended it. Which is a better idea anyway. So you have to read it first, and then construct your Cipher and CipherInputStream and decrypt the remainder of the file input stream. You don't need to read the entire file into memory to accomplish that:
public static void decrypt(File file, String password) throws Exception
{
byte[] iv = new byte[16];
DataInputStream dis = new DataInputStream(new FileInputStream(file));
dis.readFully(iv);
SecretKeySpec keySpec = new SecretKeySpec(password.getBytes(), "AES");
Cipher cipher = Cipher.getInstance("AES/CBC/NoPadding");
cipher.init(Cipher.DECRYPT_MODE, keySpec, new IvParameterSpec(iv));
CipherInputStream cis = new CipherInputStream(dis, cipher);
// Now just read plaintext from `cis` and do whatever you want with it.
cis.close();
}

Appending IV onto encrypted file for later decryption

I am trying to append a 16 byte securely generated IV onto each file after it is encrypted but before it is written. This is so that I can decrypt it later by pulling the IV off the file. This is my code so far:
public static void encrypt(byte[] file, String password, String fileName, String dir)
throws Exception {
SecureRandom r = new SecureRandom();
//128 bit IV generated for each file
byte[] iv = new byte[IV_LENGTH];
r.nextBytes(iv);
SecretKeySpec keySpec = new SecretKeySpec(password.getBytes(), "AES");
IvParameterSpec ivspec = new IvParameterSpec(iv);
Cipher cipher = Cipher.getInstance("AES/CBC/NoPadding");
cipher.init(Cipher.ENCRYPT_MODE, keySpec, ivspec);
FileOutputStream fos = new FileOutputStream(dir + fileName);
CipherOutputStream cos = new CipherOutputStream(fos, cipher);
// Have to append IV --------
cos.write(file);
fos.flush();
cos.flush();
cos.close();
fos.close();
Any suggestions on how to do this?

FileOutputStream fos = new FileOutputStream(dir + fileName);
fos.write(iv);
CipherOutputStream cos = new CipherOutputStream(fos, cipher);
should do the trick. The IV can be written to the file before the Cipher is even set up.

Android decryption: Error while finalizing cipher

I am using Android to encrypt and encrypt images sent between apps.
The encryption works well but when the file arrives at the destination it will not decrypt. Now I have copied the file at the destination app and decrypted it successfully using 3rd-party software.
The error I get is:"Error while finalizing cipher" at CipherInputStream (CipherInputStream.java:107) caused by IllegalBlockSizeException.
The encryption & decryption code is below:
public static String encrypt(String plainFile, String encryptedFile) throws IOException, NoSuchAlgorithmException,
NoSuchPaddingException, InvalidKeyException {
// Here you read the cleartext.
File extStore = Environment.getExternalStorageDirectory();
FileInputStream fis = new FileInputStream(plainFile);
// This stream write the encrypted text. This stream will be wrapped by
// another stream.
FileOutputStream fos = new FileOutputStream(encryptedFile);
// Length is 16 byte
SecretKeySpec sks = new SecretKeySpec("MyDifficultPassw".getBytes(), "AES");
// Create cipher
Cipher cipher = Cipher.getInstance("AES");
cipher.init(Cipher.ENCRYPT_MODE, sks);
// Wrap the output stream
CipherOutputStream cos = new CipherOutputStream(fos, cipher);
// Write bytes
int b;
byte[] d = new byte[8];
while ((b = fis.read(d)) != -1) {
cos.write(d, 0, b);
}
// Flush and close streams.
cos.flush();
cos.close();
fis.close();
return encryptedFile;
}
static String decrypt(String plainFile, String encryptedFile) throws IOException, NoSuchAlgorithmException,
NoSuchPaddingException, InvalidKeyException {
File encFile=new File(encryptedFile);
FileInputStream fis = new FileInputStream(encFile);
FileOutputStream fos = new FileOutputStream(plainFile);
SecretKeySpec sks = new SecretKeySpec("MyDifficultPassw".getBytes(),
"AES");
Cipher cipher = Cipher.getInstance("AES");
cipher.init(Cipher.DECRYPT_MODE, sks);
CipherInputStream cis = new CipherInputStream(fis, cipher);
int b;
byte[] d = new byte[8];
while ((b = cis.read(d)) != -1) {
fos.write(d, 0, b);
}
fos.flush();
fos.close();
cis.close();
return plainFile;
}
Any ideas? Thanks!
Ronan
Update:
The received encrypted file is consistently 1 byte smaller that the original file which seems to be generating the error. The error re block size is triggered at the code line
while ((b = fis.read(d)) != -1) { in the decrypt function.
Update:
Thanks for the feedback. The ultimate solution is as defined at last block incomplete with CipherInputStream/CipherOutputStream, even with padding AES/CBC/PKCS5Padding
Ronan