I was very excited when I learned Go had standard library support for ASN.1 as I want to write a Go implementation of my companies ASN.1 protocol, but then I realized it was DER and not BER. I need a library that has good support for BER. That said there is a 3rd party BER 'asn1-ber' library that exists on Github, but I have not had time to explore it enough, and the description for the project says it is very basic; just enough for the LDAP protocol.