Can I use different SSL certificates for each virtual host?

This is not possible if you are using Resin's virtual hosting capability to serve to multiple domain names using a single IP address.

The SSL connection (and certificate) are handled before the HTTP request is sent. Unless the domain name is mapped to a unique ip address, the server doesn't know which domain name the user is using until after SSL is set up. There is no way for Resin to determine which domain name the user has specified in the url.

It is possible if you have separate IP addresses for the hosts. You would start seperate http servers that only bind on that ip address. Each of these http servers can have seperate ssl configurations.

Why does Resin say I need OPENSSL_THREADS when I try to use OpenSSL?

Resin requires a threaded version of the OpenSSL libraries. Usually a threaded version is the default for OpenSSL, however on some systems it is necessary to explicitly request a thread version.

To recompile the openssl libraries with threading enabled:

$ cd openssl-0.9.7c
$ ./config threads
$ make
$ make install

The INSTALL document from the OpenSSL package contains more information on the threads option.

What is the sequence of handshakes for an SSL connection?

ClientHello-> 
<-ServerHello
<-CertificateChain
<-ServerHelloDone
ClientKeyExchange->
ChangeCipherSpec->
Finished->
<-ChangeCipherSpec
<-Finished