While working on #5865, you could also add generic SSL socket support to fsockopen, something like
fsockopen("ssl://example.com", ...)

don't forget to add support for client certificates/keys, including passing the password to unlock 'em (ok, this would probably require a completely new function).

for connecting to a single server, one solution is running a stunnel daemon:
stunnel -c -d 127.0.0.1:1000 -r example.com:123 -p /certs/blah.pem
and then fsockopen()ing to that port;
however, this is both a security problem (anyone on the machine can connect to that port) and useless, if one wishes to connect to a host that is not known in advance.

another option would be to allow php to talk to exec'd processes (hopefully stunnel works this way; it doesn't when piped), but this requires an extra process per request which is a resource hog. and, well, this is all in openssl already, so ...