Primer paso de la investigacion. Se aportan el .apk, las carpetas con el apk extraido y el apk descompilado. El archivo API_DOCUMENTATION.md es un archivo donde se anotaran los descubrimientos del funcionamiento de la API, y los .py son scripts para probar la funcionalidad de la API con los métodos que vayamos encontrando. Finalmente, los archivos .js son scripts de Frida para extraer informacion de la APP durante la ejecucion.

apk_decompiled/sources/kotlin/text/Charsets.java

@@ -0,0 +1,94 @@
+package kotlin.text;
+
+import java.nio.charset.Charset;
+import kotlin.Metadata;
+import kotlin.jvm.JvmField;
+import kotlin.jvm.JvmName;
+import kotlin.jvm.internal.Intrinsics;
+
+@Metadata(d1 = {"\u0000\u0014\n\u0002\u0018\u0002\n\u0002\u0010\u0000\n\u0002\b\u0002\n\u0002\u0018\u0002\n\u0002\b\u0010\bÆ\u0002\u0018\u00002\u00020\u0001B\u0007\b\u0002¢\u0006\u0002\u0010\u0002R\u0010\u0010\u0003\u001a\u00020\u00048\u0006X\u0087\u0004¢\u0006\u0002\n\u0000R\u0010\u0010\u0005\u001a\u00020\u00048\u0006X\u0087\u0004¢\u0006\u0002\n\u0000R\u0010\u0010\u0006\u001a\u00020\u00048\u0006X\u0087\u0004¢\u0006\u0002\n\u0000R\u0010\u0010\u0007\u001a\u00020\u00048\u0006X\u0087\u0004¢\u0006\u0002\n\u0000R\u0010\u0010\b\u001a\u00020\u00048\u0006X\u0087\u0004¢\u0006\u0002\n\u0000R\u0011\u0010\t\u001a\u00020\u00048G¢\u0006\u0006\u001a\u0004\b\n\u0010\u000bR\u0011\u0010\f\u001a\u00020\u00048G¢\u0006\u0006\u001a\u0004\b\r\u0010\u000bR\u0011\u0010\u000e\u001a\u00020\u00048G¢\u0006\u0006\u001a\u0004\b\u000f\u0010\u000bR\u0010\u0010\u0010\u001a\u00020\u00048\u0006X\u0087\u0004¢\u0006\u0002\n\u0000R\u0010\u0010\u0011\u001a\u0004\u0018\u00010\u0004X\u0082\u000e¢\u0006\u0002\n\u0000R\u0010\u0010\u0012\u001a\u0004\u0018\u00010\u0004X\u0082\u000e¢\u0006\u0002\n\u0000R\u0010\u0010\u0013\u001a\u0004\u0018\u00010\u0004X\u0082\u000e¢\u0006\u0002\n\u0000¨\u0006\u0014"}, d2 = {"Lkotlin/text/Charsets;", "", "()V", "ISO_8859_1", "Ljava/nio/charset/Charset;", "US_ASCII", "UTF_16", "UTF_16BE", "UTF_16LE", "UTF_32", "UTF32", "()Ljava/nio/charset/Charset;", "UTF_32BE", "UTF32_BE", "UTF_32LE", "UTF32_LE", "UTF_8", "utf_32", "utf_32be", "utf_32le", "kotlin-stdlib"}, k = 1, mv = {1, 9, 0}, xi = 48)
+/* loaded from: classes3.dex */
+public final class Charsets {
+    public static final Charsets INSTANCE = new Charsets();
+
+    @JvmField
+    public static final Charset ISO_8859_1;
+
+    @JvmField
+    public static final Charset US_ASCII;
+
+    @JvmField
+    public static final Charset UTF_16;
+
+    @JvmField
+    public static final Charset UTF_16BE;
+
+    @JvmField
+    public static final Charset UTF_16LE;
+
+    @JvmField
+    public static final Charset UTF_8;
+    private static volatile Charset utf_32;
+    private static volatile Charset utf_32be;
+    private static volatile Charset utf_32le;
+
+    static {
+        Charset forName = Charset.forName("UTF-8");
+        Intrinsics.checkNotNullExpressionValue(forName, "forName(...)");
+        UTF_8 = forName;
+        Charset forName2 = Charset.forName("UTF-16");
+        Intrinsics.checkNotNullExpressionValue(forName2, "forName(...)");
+        UTF_16 = forName2;
+        Charset forName3 = Charset.forName("UTF-16BE");
+        Intrinsics.checkNotNullExpressionValue(forName3, "forName(...)");
+        UTF_16BE = forName3;
+        Charset forName4 = Charset.forName("UTF-16LE");
+        Intrinsics.checkNotNullExpressionValue(forName4, "forName(...)");
+        UTF_16LE = forName4;
+        Charset forName5 = Charset.forName("US-ASCII");
+        Intrinsics.checkNotNullExpressionValue(forName5, "forName(...)");
+        US_ASCII = forName5;
+        Charset forName6 = Charset.forName("ISO-8859-1");
+        Intrinsics.checkNotNullExpressionValue(forName6, "forName(...)");
+        ISO_8859_1 = forName6;
+    }
+
+    private Charsets() {
+    }
+
+    @JvmName(name = "UTF32")
+    public final Charset UTF32() {
+        Charset charset = utf_32;
+        if (charset != null) {
+            return charset;
+        }
+        Charset forName = Charset.forName("UTF-32");
+        Intrinsics.checkNotNullExpressionValue(forName, "forName(...)");
+        utf_32 = forName;
+        return forName;
+    }
+
+    @JvmName(name = "UTF32_BE")
+    public final Charset UTF32_BE() {
+        Charset charset = utf_32be;
+        if (charset != null) {
+            return charset;
+        }
+        Charset forName = Charset.forName("UTF-32BE");
+        Intrinsics.checkNotNullExpressionValue(forName, "forName(...)");
+        utf_32be = forName;
+        return forName;
+    }
+
+    @JvmName(name = "UTF32_LE")
+    public final Charset UTF32_LE() {
+        Charset charset = utf_32le;
+        if (charset != null) {
+            return charset;
+        }
+        Charset forName = Charset.forName("UTF-32LE");
+        Intrinsics.checkNotNullExpressionValue(forName, "forName(...)");
+        utf_32le = forName;
+        return forName;
+    }
+}