On Thu, May 21, 2020 at 06:53:39PM -0400, paul h. roubekas wrote: > I have a requirement to convert all certs in a *.p12 file to a *.der file > for use in the curl command. Perhaps I can crystalise some of the replies for you. The basic issue is that **DER is not a file format**, rather: * DER is binary encoding for a single data structure (object, a.k.a. PDU or Protocol Data Unit), generally used only for objects with a standardised ASN.1 schema. One can of course write a DER serialied data structure to a file, transmit it in network packet, ... But, what one can't do (in contrast with PEM) is just concatenate multiple DER objects together to get a meaningful multi-object store. For that, you need a standardised container structure that can be written in DER form, that *internally* holds multiple objects. Ideally, something less bletcherous than PKCS#12 (inflicted on humanity by some sadistic deity as punishment for ancestral sins). -- Viktor.