private static @Nullable SecretKey loadSymmetricKey(Context context, KeyPair wrapperKey) throws NoSuchPaddingException,
	                                                                                                NoSuchAlgorithmException,
	                                                                                                InvalidKeyException {
		String encryptedSymmetricKey = getKeyPrefs(context).getString(PREFS_KEY_SYMMETRIC_KEY, null);
		if (StringUtils.isNullOrEmpty(encryptedSymmetricKey)) {
			return null;
		}

		return unwrapSymmetricKey(wrapperKey, encryptedSymmetricKey);
	}
private static @ Nullable SecretKey loadSymmetricKey ( Context context , KeyPair wrapperKey ) throws NoSuchPaddingException , NoSuchAlgorithmException , InvalidKeyException { String encryptedSymmetricKey = getKeyPrefs ( context ) . getString ( PREFS_KEY_SYMMETRIC_KEY , null ) ; if ( StringUtils . isNullOrEmpty ( encryptedSymmetricKey ) ) { return null ; } return unwrapSymmetricKey ( wrapperKey , encryptedSymmetricKey ) ; }
Attempts to load an existing symmetric key or return <code>null</code> if failed.
Multistep process:
1. Load and encrypted symmetric key data from the shared preferences.
2. Unwraps the key using <code>wrapperKey</code>