com.linecorp.android.security.encryption

Class StringCipher

java.lang.Object

com.linecorp.android.security.encryption.StringCipher

@WorkerThread
public class StringCipher
extends java.lang.Object

Class to encrypt/decrypt string data. This has the following features. - derives a device-specific key - randomizes encrypted data (uses AES-CBS with a random IV) - provides integrity protection (applies HMAC to encrypted data)

This uses SharedPreferences to save the salt of encryption. Please specify a unique name as the constructor parameter that represents Shared Preference name.

Either first access of encrypt(Context, String), decrypt(Context, String) or initialize(Context) is very slow because there is secret key generation with PBKDF2. We recommend that you initialize an instance of this class beforehand and cache it.

Constructor Summary

Constructors

Constructor and Description
StringCipher(java.lang.String sharedPreferenceName)
StringCipher(java.lang.String sharedPreferenceName, int pbkdf2IterationCount, boolean isSerialIncludedInDevicePackageSpecificId)

Method Summary

Modifier and Type	Method and Description
java.lang.String	decrypt(Context context, java.lang.String b64CipherText)
java.lang.String	encrypt(Context context, java.lang.String plainText)
void	initialize(Context context)

Methods inherited from class java.lang.Object

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

Constructor Detail

StringCipher

public StringCipher(@NonNull
                    java.lang.String sharedPreferenceName)

StringCipher

public StringCipher(@NonNull
                    java.lang.String sharedPreferenceName,
                    int pbkdf2IterationCount,
                    boolean isSerialIncludedInDevicePackageSpecificId)

Parameters:

sharedPreferenceName - shared pref name used to save salt

pbkdf2IterationCount - number of iteration used for encryption

isSerialIncludedInDevicePackageSpecificId - Indicates if we should also include Build.Serial as an identifier to generate the device Id. Note : This field should always be false as it is deprecated and returns UNKNOWN in some cases from Android SDK >= 27

Method Detail

initialize

public void initialize(@NonNull
                       Context context)

encrypt

@NonNull
public java.lang.String encrypt(@NonNull
                                         Context context,
                                         @NonNull
                                         java.lang.String plainText)

decrypt

@NonNull
public java.lang.String decrypt(@NonNull
                                         Context context,
                                         @NonNull
                                         java.lang.String b64CipherText)