package main

import "encoding/asn1"

func main() {
    data := []byte("0\x05\f\x03a\xc9c")
    v := X{}
    _, err := asn1.Unmarshal(data, &v)
    if err != nil {
        panic("Unmarshal: " + err.Error())
    }
    _, err = asn1.Marshal(v)
    if err != nil {
        panic("Marshal: " + err.Error())
    }
}

type X struct {
    S string //`asn1:"utf8"`
}