sveinungkb / encrypted-userprefs Goto Github PK

A slightly less insecure wrapper for SharedUserPreferences for Android. Keys and values encrypted using a symmetric cipher.

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encrypted-userprefs's Introduction

encrypted-userprefs

An encrypted and slightly less insecure wrapper for SharedPreferences for Android. SharedPreferences on Android stores all of your values in "plain text", simply protected by the user-restricted file system on Android. If you gain root access to an Android device you have full read/write access to the application preferences of all of the applications installed.

Many applications store some kind of application secret (e.g. a communication token, last used account number) using SharedPreferences.

By using this class you'll protect your preferences with a strong and proven symmetric cipher (AES) which will make it harder for anyone wishing to extract information from your application.

PS: This will not make your application bulletproof, just better :)

Example:

A regular shared preference file looks like this from adb shell:

cat /data/data/your.package.application/shared_prefs/prefs-test.xml
<?xml version='1.0' encoding='utf-8' standalone='yes' ?>
<map>
<string name="hemmelighet">dette er en hemmelighet</string>
</map>

With encryption you get a less obvious version:

cat /data/data/your.package.application/shared_prefs/prefs-test.xml
<?xml version='1.0' encoding='utf-8' standalone='yes' ?>
<map>
<string name="JopRH053b7Ogw17Yxmh7Og==">0AB7Y28XEvbQcnXpEZ4j9PtqzFLtm2V3KBXjTO1V704=</string>
</map>

The key is "hemmelighet" and the value is "dette er en hemmelighet".

Usage:

// Init
SecurePreferences preferences = new SecurePreferences(context, "my-preferences", "SometopSecretKey1235", true);
// Put (all puts are automatically committed)
preferences.put("userId", "User1234");
// Get
String user = preferences.getString("userId");

Requirements and limitation:

Android API Level 8 (for Base64 support). Only strings put/gets are supported for now, this should cover most usages.

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encrypted-userprefs's Issues

Regarding Issue

Hi,
I got the following error in your attached github code.
It worked fine for two days of rigorous testing but crashed the third day of testing.
"error:1e06b065:Cipher functions:EVP_DecryptFinal_ex:BAD_DECRYPT"
The only difference in the code is the creation of SecretKeySpec object.
I generated it in the following way
secretKey = new SecretKeySpec(hexStringToByteArray(), "AES");
private static byte[] hexStringToByteArray() {
int len = key.length();
byte[] data = new byte[len / 2];

    for (int i = 0; i < len; i += 2) {
        data[i / 2] = (byte) ((Character.digit(key.charAt(i), 16) << 4) + Character.digit(key.charAt(i + 1), 16));
    }
    return data;
}

Any tips/advice on this?
My usecase involves storing of Pojo objects as string for encryption.

how to use my own key for encryption ?

I cannot figure out where you have mentioned the encryption key in the code. Can you please tell me how to use my own key for encryption ? @sveinungkb

Seeing some of javax.crypto.BadPaddingException: pad block corrupted

com.app.utils.SecurePreferences$SecurePreferencesException: javax.crypto.BadPaddingException: pad block corrupted
at com.app.utils.SecurePreferences.convert(SecurePreferences.java:193)
at com.app.utils.SecurePreferences.decrypt(SecurePreferences.java:179)
at com.app.utils.SecurePreferences.getString(SecurePreferences.java:136)

Any idea why ?
Thanks
Shimi