how to open ASN.1 coded hex file
Open as in "show structure" see "man asn1parse" from the OpenSSL toolkit.
how to decode it.
BER is a subformat of DER which is encoding for ASN.1.
Since OpenSSL generates PEM, to convert PEM to DER your route would be:
"openssl x509 -inform PEM -outform DER -in cert.pem -out cert.der"
so reversing the route should then be:
"openssl x509 -inform DER -outform PEM -in cert.der -out cert.pem".
"man x509" for more information.