com.securepreferences

Class SecurePreferences

java.lang.Object

com.securepreferences.SecurePreferences

All Implemented Interfaces:

android.content.SharedPreferences

public class SecurePreferences
extends java.lang.Object
implements android.content.SharedPreferences

Wrapper class for Android's SharedPreferences interface, which adds a layer of encryption to the persistent storage and retrieval of sensitive key-value pairs of primitive data types.

This class provides important - but nevertheless imperfect - protection against simple attacks by casual snoopers. It is crucial to remember that even encrypted data may still be susceptible to attacks, especially on rooted devices

Recommended to use with user password, in which case the key will be derived from the password and not stored in the file.

TODO: Handle OnSharedPreferenceChangeListener

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
class	SecurePreferences.Editor Wrapper for Android's SharedPreferences.Editor.

Nested classes/interfaces inherited from interface android.content.SharedPreferences

android.content.SharedPreferences.OnSharedPreferenceChangeListener

Constructor Summary

Constructors

Constructor and Description
SecurePreferences(android.content.Context context) User password defaults to app generated password that's stores obfucated with the other preference values.
SecurePreferences(android.content.Context context, AesCbcWithIntegrity.SecretKeys secretKey, java.lang.String sharedPrefFilename)
SecurePreferences(android.content.Context context, int iterationCount)
SecurePreferences(android.content.Context context, java.lang.String salt)
SecurePreferences(android.content.Context context, java.lang.String password, java.lang.String sharedPrefFilename)
SecurePreferences(android.content.Context context, java.lang.String password, java.lang.String sharedPrefFilename, int iterationCount)
SecurePreferences(android.content.Context context, java.lang.String password, java.lang.String salt, java.lang.String sharedPrefFilename, int iterationCount)

Method Summary

Modifier and Type	Method and Description
boolean	contains(java.lang.String key)
void	destroyKeys() nulls in memory keys
SecurePreferences.Editor	edit()
java.util.Map<java.lang.String,java.lang.String>	getAll()
boolean	getBoolean(java.lang.String key, boolean defaultValue)
java.lang.String	getEncryptedString(java.lang.String key, java.lang.String defaultValue) Added to get a values as as it can be useful to store values that are already encrypted and encoded
float	getFloat(java.lang.String key, float defaultValue)
int	getInt(java.lang.String key, int defaultValue)
long	getLong(java.lang.String key, long defaultValue)
java.lang.String	getString(java.lang.String key, java.lang.String defaultValue)
java.util.Set<java.lang.String>	getStringSet(java.lang.String key, java.util.Set<java.lang.String> defaultValues)
void	handlePasswordChange(java.lang.String newPassword, android.content.Context context)
void	handlePasswordChange(java.lang.String newPassword, android.content.Context context, int iterationCount) Cycle through the unencrypt all the current prefs to mem cache, clear, then encypt with key generated from new password.
static java.lang.String	hashPrefKey(java.lang.String prefKey) The Pref keys must be same each time so we're using a hash to obscure the stored value
static boolean	isLoggingEnabled()
void	registerOnSharedPreferenceChangeListener(android.content.SharedPreferences.OnSharedPreferenceChangeListener listener)
void	registerOnSharedPreferenceChangeListener(android.content.SharedPreferences.OnSharedPreferenceChangeListener listener, boolean decryptKeys)
static void	setLoggingEnabled(boolean loggingEnabled)
void	unregisterOnSharedPreferenceChangeListener(android.content.SharedPreferences.OnSharedPreferenceChangeListener listener)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

SecurePreferences

public SecurePreferences(android.content.Context context)

User password defaults to app generated password that's stores obfucated with the other preference values. Also this uses the Default shared pref file

Parameters:

context - should be ApplicationContext not Activity

SecurePreferences

public SecurePreferences(android.content.Context context,
                         java.lang.String salt)

Parameters:

context - should be ApplicationContext not Activity

salt - is custom salt you choose for encryption

SecurePreferences

public SecurePreferences(android.content.Context context,
                         int iterationCount)

Parameters:

context - should be ApplicationContext not Activity

iterationCount - The iteration count for the keys generation

SecurePreferences

public SecurePreferences(android.content.Context context,
                         java.lang.String password,
                         java.lang.String sharedPrefFilename)

Parameters:

context - should be ApplicationContext not Activity

password - user password/code used to generate encryption key.

sharedPrefFilename - name of the shared pref file. If null use the default shared prefs

SecurePreferences

public SecurePreferences(android.content.Context context,
                         java.lang.String password,
                         java.lang.String sharedPrefFilename,
                         int iterationCount)

Parameters:

context - should be ApplicationContext not Activity

iterationCount - The iteration count for the keys generation

SecurePreferences

public SecurePreferences(android.content.Context context,
                         AesCbcWithIntegrity.SecretKeys secretKey,
                         java.lang.String sharedPrefFilename)

Parameters:

context - should be ApplicationContext not Activity

secretKey - that you've generated

sharedPrefFilename - name of the shared pref file. If null use the default shared prefs

SecurePreferences

public SecurePreferences(android.content.Context context,
                         java.lang.String password,
                         java.lang.String salt,
                         java.lang.String sharedPrefFilename,
                         int iterationCount)

Parameters:

context - should be ApplicationContext not Activity

iterationCount - The iteration count for the keys generation

Method Detail

destroyKeys

public void destroyKeys()

nulls in memory keys

hashPrefKey

public static java.lang.String hashPrefKey(java.lang.String prefKey)

The Pref keys must be same each time so we're using a hash to obscure the stored value

Parameters:

prefKey -

Returns:

SHA-256 Hash of the preference key

getAll

public java.util.Map<java.lang.String,java.lang.String> getAll()

Specified by:

getAll in interface android.content.SharedPreferences

Returns:

map of with decrypted values (excluding the key if present)

getString

public java.lang.String getString(java.lang.String key,
                                  java.lang.String defaultValue)

Specified by:

getString in interface android.content.SharedPreferences

getEncryptedString

public java.lang.String getEncryptedString(java.lang.String key,
                                           java.lang.String defaultValue)

Added to get a values as as it can be useful to store values that are already encrypted and encoded

Parameters:

key - pref key

defaultValue -

Returns:

Encrypted value of the key or the defaultValue if no value exists

getStringSet

public java.util.Set<java.lang.String> getStringSet(java.lang.String key,
                                                    java.util.Set<java.lang.String> defaultValues)

Specified by:

getStringSet in interface android.content.SharedPreferences

getInt

public int getInt(java.lang.String key,
                  int defaultValue)

Specified by:

getInt in interface android.content.SharedPreferences

getLong

public long getLong(java.lang.String key,
                    long defaultValue)

Specified by:

getLong in interface android.content.SharedPreferences

getFloat

public float getFloat(java.lang.String key,
                      float defaultValue)

Specified by:

getFloat in interface android.content.SharedPreferences

getBoolean

public boolean getBoolean(java.lang.String key,
                          boolean defaultValue)

Specified by:

getBoolean in interface android.content.SharedPreferences

contains

public boolean contains(java.lang.String key)

Specified by:

contains in interface android.content.SharedPreferences

handlePasswordChange

public void handlePasswordChange(java.lang.String newPassword,
                                 android.content.Context context,
                                 int iterationCount)
                          throws java.security.GeneralSecurityException

Cycle through the unencrypt all the current prefs to mem cache, clear, then encypt with key generated from new password. This method can be used if switching from the generated key to a key derived from user password

Note: the pref keys will remain the same as they are SHA256 hashes.

Parameters:

newPassword -

context - should be ApplicationContext not Activity

iterationCount - The iteration count for the keys generation

Throws:

java.security.GeneralSecurityException

handlePasswordChange

public void handlePasswordChange(java.lang.String newPassword,
                                 android.content.Context context)
                          throws java.security.GeneralSecurityException

Throws:

java.security.GeneralSecurityException

edit

public SecurePreferences.Editor edit()

Specified by:

edit in interface android.content.SharedPreferences

isLoggingEnabled

public static boolean isLoggingEnabled()

setLoggingEnabled

public static void setLoggingEnabled(boolean loggingEnabled)

registerOnSharedPreferenceChangeListener

public void registerOnSharedPreferenceChangeListener(android.content.SharedPreferences.OnSharedPreferenceChangeListener listener)

Specified by:

registerOnSharedPreferenceChangeListener in interface android.content.SharedPreferences

registerOnSharedPreferenceChangeListener

public void registerOnSharedPreferenceChangeListener(android.content.SharedPreferences.OnSharedPreferenceChangeListener listener,
                                                     boolean decryptKeys)

Parameters:

listener - OnSharedPreferenceChangeListener

decryptKeys - Callbacks receive the "key" parameter decrypted

unregisterOnSharedPreferenceChangeListener

public void unregisterOnSharedPreferenceChangeListener(android.content.SharedPreferences.OnSharedPreferenceChangeListener listener)

Specified by:

unregisterOnSharedPreferenceChangeListener in interface android.content.SharedPreferences