Certdump handles DER certificates as well now.

lib/lib.go

@@ -11,6 +11,8 @@ var progname = filepath.Base(os.Args[0])
 
 // ProgName returns what lib thinks the program name is, namely the
 // basename of of argv0.
+//
+// It is similar to the Linux __progname.
 func ProgName() string {
 	return progname
 }