+/**
+ * Gets the Daily Tracing Key for the device in binary format.
+ *
+ * For internal use. It generally makes more sense to use the
+ * contrac_get_daily_key() function instead.
+ *
+ * This allows the Daily Tracing Key to be extracted. The Daily Tracing Key
+ * should be kept secret (to maintain privacy) until a positive test is
+ * confirmed, at which point the user may choose to upload the key to a
+ * Diagnosis Server, so that others can be notified.
+ *
+ * The buffer returned will contain exactly DTK_SIZE (16) bytes of data in
+ * binary format. This may therefore contain null bytes, and the buffer will not
+ * necessarily be null terminated. Future operations may cause the data to
+ * change, so the caller should make a copy of the buffer rather than keeping
+ * a pointer to it.
+ *
+ * @param data The context object to work with.
+ * @return The Daily Tracing Key in binary format, not null terminated.
+ */
+unsigned char const * dtk_get_daily_key(Dtk const * data) {