Using encryption to store data

Using all the methods discussed in the earlier sections, you can now encrypt any information in your application, as shown in the following code:

String myData = "My secret information";

SecretKeySpec sks = generateKey();
byte[] encoded = encrypt(myData, sks);
String decoded = decrypt(encoded, sks);

Log.d("MAIN - Encoded: ", 
Base64.encodeToString(encoded, Base64.DEFAULT));
Log.d("MAIN - Decoded: ", decoded);

The results generated in LogCat are shown in the following screenshot:

The previous example can be adapted to encrypt the content of a file on the internal storage of your application, as shown in the following code:

String myData = "My secret information in my internal file";
SecretKeySpec sks = generateKey();
byte[] encoded = encrypt(myData, sks);

FileOutputStream fos = 
openFileOutput("MyEncryptedFile.txt", Context.MODE_PRIVATE);
fos.write(encoded);
fos.close();

On executing the code in your main activity, the MyEncryptedFile.txt file will be created...