handle PKCS#7 CompressedData

[dkg]

gmime currently has some commented out/unimplemented functions for handling PKCS#7 CompressedData messages. These should be implemented, so i'm just recording that as an open issue.

The functions in particular are:

• g_mime_application_pkcs7_mime_compress
• g_mime_application_pkcs7_mime_decompress

for specification reference, see § 3.6 of RFC 8551

[jstedfast]

Yea, I think I aborted my efforts on support for this because I wasn't sure how to do it using GpgME.

[dkg]

I don't think it should require gpgme at all -- compression and decompression are completely unrelated to cryptography, they just happen to use the same PKCS#7 framing.

[jstedfast]

Sure, but I was hoping gpgme supported it because otherwise I need to implement asn1 myself.

Maybe I can use libksba, but that looks like it's missing some API that might be needed. Hard to tell right now.

I'll also need to add new virtual methods for this (theoretically), so this may be best as a v4.0 API as well.

[sakwaa]

Are there any updates to the implementation for the compress/decompress? I ran into the same issue.. I have a multipart/signed part with a compressed message and I can't figure out how to decompress to get the message contents as readable text. Thanks!

[jstedfast]

No updates. I haven't had enough free time to look into this yet.