Fix automatic data reset on for users affected by encryption issues (EXPOSUREAPP-3313, EXPOSUREAPP-3335)

[d4rken]

The automatic data reset for users affected by #642 does unfortunately not match ☹️.
We overlooked that KeyException is a subclass of GeneralSecurityException.
This causes us to abort early and continue with KeyException which then fails the error message matching test.
As the underlying Tink code throws the GeneralSecurityException first and should have no further causes, I've changed the code to not iterate, but directly pick the last exception in the list of causes.

Test

This can't be easily tested on device.
Understand the original exception flow in the stracktrace provided by a user and confirm that this is now fixed and the unit test correctly covers this case.

time: 1603116265174
msg: java.security.GeneralSecurityException: decryption failed
stacktrace: java.lang.RuntimeException: Unable to create application de.rki.coronawarnapp.CoronaWarnApplication: de.rki.coronawarnapp.exception.CwaSecurityException: something went wrong during a critical part of the application ensuring security, please referto the details for more information
	at android.app.ActivityThread.handleBindApplication(ActivityThread.java:6465)
	at android.app.ActivityThread.access$1300(ActivityThread.java:219)
	at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1859)
	at android.os.Handler.dispatchMessage(Handler.java:107)
	at android.os.Looper.loop(Looper.java:214)
	at android.app.ActivityThread.main(ActivityThread.java:7356)
	at java.lang.reflect.Method.invoke(Native Method)
	at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:491)
	at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:925)
Caused by: de.rki.coronawarnapp.exception.CwaSecurityException: something went wrong during a critical part of the application ensuring security, please referto the details for more information
	at de.rki.coronawarnapp.util.security.SecurityHelper$encryptedPreferencesProvider$1.invoke(SecurityHelper.kt:9)
	at de.rki.coronawarnapp.util.security.SecurityHelper$globalEncryptedSharedPreferencesInstance$2.invoke(SecurityHelper.kt:3)
	at kotlin.SynchronizedLazyImpl.getValue(LazyJVM.kt:6)
	at de.rki.coronawarnapp.util.security.SecurityHelper.getGlobalEncryptedSharedPreferencesInstance(Unknown Source:2)
	at de.rki.coronawarnapp.storage.LocalData.getSharedPreferenceInstance(LocalData.kt:1)
	at de.rki.coronawarnapp.CoronaWarnApplication.onCreate(CoronaWarnApplication.kt:42)
	at android.app.Instrumentation.callApplicationOnCreate(Instrumentation.java:1190)
	at android.app.ActivityThread.handleBindApplication(ActivityThread.java:6460)
	... 8 more
Caused by: java.security.KeyException: Permantly failed to instantiate encrypted preferences
	at de.rki.coronawarnapp.util.security.EncryptedPreferencesFactory.create(EncryptedPreferencesFactory.kt:2)
	at de.rki.coronawarnapp.util.security.SecurityHelper$encryptedPreferencesProvider$1$1.invoke(SecurityHelper.kt:1)
	at de.rki.coronawarnapp.util.security.SecurityHelper$encryptedPreferencesProvider$1.invoke(SecurityHelper.kt:7)
	... 15 more
Caused by: java.lang.SecurityException: Could not decrypt key. decryption failed
	at androidx.security.crypto.EncryptedSharedPreferences.getAll(EncryptedSharedPreferences.java:13)
	at de.rki.coronawarnapp.util.security.EncryptedPreferencesFactory$create$1.invoke(EncryptedPreferencesFactory.kt:29)
	at de.rki.coronawarnapp.util.RetryMechanism.retryWithBackOff$default(RetryMechanism.kt:7)
	at de.rki.coronawarnapp.util.security.EncryptedPreferencesFactory.create(EncryptedPreferencesFactory.kt:1)
	... 17 more
Caused by: java.security.GeneralSecurityException: decryption failed
	at com.google.crypto.tink.daead.DeterministicAeadWrapper$WrappedDeterministicAead.decryptDeterministically(DeterministicAeadWrapper.java:16)
	at androidx.security.crypto.EncryptedSharedPreferences.getAll(EncryptedSharedPreferences.java:8)
	... 20 more

[d4rken]

Marked as DO NOT MERGE as I want to leave the option open to rebase this against release/1.5.x if we decide that there will be a hotfix.

[d4rken]

I rebased this against 1.5.x.

I added an additional test case case and changed the explanation dialog behavior slightly.
It will no longer dismiss the dialog when the user clicks details and visits the FAQ.
It's possible that the user clicks "details" before reading everything or wants to read it again.
The dialog will now only dismiss when pressing "OK".

Before doing on device tests, please review the code and test cases again.
To test on device you can start by adding an exception like this to SecurityHelper:

        withSecurityCatch {
            try {
                factory.create(ENCRYPTED_SHARED_PREFERENCES_FILE)
// ################
                throw KeyException(
                    "Permantly failed to instantiate encrypted preferences",
                    SecurityException(
                        "Could not decrypt key. decryption failed",
                        GeneralSecurityException("decryption failed")
                    )
                )
// ################
            } catch (e: Exception) {
                if (encryptionErrorResetTool.tryResetIfNecessary(e)) {
                    Timber.w("We could recovery from this error via reset. Now retrying.")
                    factory.create(ENCRYPTED_SHARED_PREFERENCES_FILE)
                } else {
                    throw e
                }
            }
        }

[sonarcloud]

Kudos, SonarCloud Quality Gate passed!

0 Bugs
0 Vulnerabilities (and 0 Security Hotspots to review)
0 Code Smells

29.4% Coverage
0.0% Duplication

[harambasicluka]

@BMItter will also review this PR, as it is not testable for our testers.

[BMItr]

LGTM, also toast handling i.o, exception handling i.o