Feature request: Extend PEM parsing to support additional formats

[wiedem]

The PEM parsing and generation implemented in PEMDocument doesn't fully support the PEM format as defined in RFC1421.

In particular, fields such as Proc-Type and DEK-INFO are not supported, which means that formats as defined in RFC5915 cannot be processed:

-----BEGIN EC PRIVATE KEY-----
Proc-Type: 4,ENCRYPTED
DEK-Info: AES-256-CBC,A4E9C3555C149C675E03B622A42500D2

<snip>
-----END EC PRIVATE KEY-----

It would be advantageous if the processing of these additional fields were supported by the PEMDocument, as otherwise some PEM files cannot be processed properly.

[Lukasa]

Yeah this is totally an existing limitation. I believe we designed the type such that extending it for this use-case was possible, but the core feature set didn’t require it. We’d welcome a PR to add the function.