Add DNSCrypt support to personal AdGuard DNS

[ameshkov]

Issue Details

We currently only support DoH / DoT / DoQ there. It would be logical to add DNSCrypt support as well.

Proposed solution

In order to make "personal" part work we can use "Provider Name" field to recognize the user that makes a query. This "provider name" will be sent to AdGuard DNS server when fetching the certificate. Once we receive such a query, we can return a personal certificate of that user and then use the "Client Magic" value of that cert to recognize user's encrypted queries.

Alternative solution

No response

[TPS]

@ameshkov Any progress on this? Maybe a "hacky" way to do this? It is a bit frustrating to see sdns:// addressing on https://adguard-dns.io/en/public-dns.html, but not for the paid subscription.

[ameshkov]

There's not enough demand to justify quite a lot of time we'll need to spend on the feature

[TPS]

@ameshkov Are wildcard certs a thing in sdns like for SSL/TLS?