feat(app): implement Google Play App Licensing

Signed-off-by: YuutaW <17158086+Trumeet@users.noreply.github.com>

1 files changed, 32 insertions, 0 deletions

diff --git a/app/src/main/java/moe/yuuta/gplicense/Obfuscator.java b/app/src/main/java/moe/yuuta/gplicense/Obfuscator.java
new file mode 100644
index 0000000..e89030c
--- /dev/null
+++ b/app/src/main/java/moe/yuuta/gplicense/Obfuscator.java
@@ -0,0 +1,32 @@
+package moe.yuuta.gplicense;
+
+/**
+ * Interface used as part of a {@link Policy} to allow application authors to obfuscate
+ * licensing data that will be stored into a SharedPreferences file.
+ * <p>
+ * Any transformation scheme must be reversable. Implementing classes may optionally implement an
+ * integrity check to further prevent modification to preference data. Implementing classes
+ * should use device-specific information as a key in the obfuscation algorithm to prevent
+ * obfuscated preferences from being shared among devices.
+ */
+public interface Obfuscator {
+
+    /**
+     * Obfuscate a string that is being stored into shared preferences.
+     *
+     * @param original The data that is to be obfuscated.
+     * @param key The key for the data that is to be obfuscated.
+     * @return A transformed version of the original data.
+     */
+    String obfuscate(String original, String key);
+
+    /**
+     * Undo the transformation applied to data by the obfuscate() method.
+     *
+     * @param obfuscated The data that is to be un-obfuscated.
+     * @param key The key for the data that is to be un-obfuscated.
+     * @return The original data transformed by the obfuscate() method.
+     * @throws ValidationException Optionally thrown if a data integrity check fails.
+     */
+    String unobfuscate(String obfuscated, String key) throws ValidationException;
+}
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