fixed keygen encryption prompt

src/bin/duralumin-keygen.rs

@@ -77,7 +77,7 @@ fn main() -> OsshResult<()> {
         std::io::stdin().read_line(&mut line)?;
         fix_newline_ref(&mut line);
 
-        line.to_lowercase() == "y"
+        line.to_lowercase() != "n"
     };
 
     if encrypt {