Add PGP: WKD support& batch async

[noob6t5]

I had this running from long time so i don't miss any email's of target and surprisingly there is difference betn 100's of email with this and without this ,it collect's email from subdomains too if user want for certain domain they can grep for it .... and Since wkd is added i tried to add description user friendly too ..

I just remembered while checking todo by @TheTechromancer ,at last i have tried to polish and keep ir lightweight as possible , please do review and

Can we add this @liquidsec ?? Please let me know what can we do about this PR ...

[liquidsec]

Hey @noob6t5, i know this has been sitting a long time so wanted to make sure to get you some feedback. First i noticed a bug in the original (#2960) - just noting that here since that will be being fixed shortly.

here are some of the issues with your PR version of the module that would need to be addressed:

• it seems that the URL is wrong for WKD urls. Your lookup is:

https://{query}/.well-known/openpgpkey/hu/{query}

where query is a domain like example.com.

However, WKD lookups are based on an email address, not a domain. The path component must be a z-base-32 encoded SHA-1 hash of the local part of the email address.

For example:

https://example.com/.well-known/openpgpkey/hu/{hash}

where:

hash = zbase32(SHA1(lowercase(localpart)))

So, you can't look up a WKD by domain, WKD is for looking up keys by email address. Since this module receives DNS_NAME events (domains) and doesn't know specific email addresses, WKD doesn't seem to work here. You'd need known email addresses first. So there's a chicken-egg problem.

A couple other code quality / BBOT standards notes also:

• The PR uses raw asyncio.Semaphore and asyncio.gather instead of BBOT's built-in self.helpers.request_batch() or the module's _module_threads attribute. The existing request_batch already handles concurrent requests.
• The _cache dict seems to duplicate what BBOT's dedup system already does. A domain wont be scanned twice.
• We should never be super()'ing init in bbot, for a variety of reasons.
• You have a bare exception - we don't allow those in BBOT since they can swallow errors silently.
• Every module needs a test to go along with it, this is a requirement that is enforced by the our CI/CD pipeline.

[liquidsec]

For now - I'm going to close the PR. I think the only thing you'd really get from WKD endpoints is confirmation that an email is valid, which doens't fit with this module anyway.