Add support for other e2e encryption types

[moparisthebest]

This adds support for OMEMO, XEP-27 PGP, and XEP-373 OX PGP. I made each configurable so you could set up a server that only allowed OMEMO for instance.

Arguably you'd rename this to mod_e2e or something, but I didn't go that far. :)

[herbsmn]

Hey @iNPUTmice, do you have any thoughts on this?

[micah]

this looks good!

[herbsmn]

thoughts @dgoulet?

[elijh]

This is awesome! Could you also allow messages for MUC to pass through if mandatory is enabled and the message is OMEMO or OpenPGP?

[elijh]

To be more clear, there appears to be a bug in this patch:

This patch will break the 'mixed' mode (require OTR except for MUC). In our test, this patch will make encryption required for MUC, even when running in 'mixed' mode.

[moparisthebest]

This doesn't break mixed mode, all it does is additionally allow messages through if they are OMEMO or PGP. You might want to re-think your mixed mode though, because OMEMO/PGP can work in MUCs as well.

[elijh]

We thought that it would allow mixed mode too. But when we installed this patch with mixed mode on, all the MUCs stopped working.

Yes, we would like to drop mixed mode in the future, once more people have transitioned to omemo, but for now we want to be able to require encryption for user to user chats and make it optional for muc. One problem is the omemo group chats only work under specific circumstances (private groups, everyone in the group subscribed to status updates from everyone else).

[moparisthebest]

You can see the change, I literally added allows for omemo/pgp, and didn't change any mixed mode logic. It works as it did before, are you sure you set it right?

[Neustradamus]

Any news?