Robots.txt might not be the solution here. I don't know your site configuration but in the past the people that have asked this question were mirroring their robots.txt file on https & http. In that situation blocking anything would block both. You also mention that you are interested in redirecting, you should look into using isapi rewrite. That could resolve both issues for you.
Msg#: 3699828 posted 1:18 pm on Aug 9, 2008 (gmt 0)
yes on appache servers it is best to use .htaccess.. but you can not restrict all url(s), robots.txt file may be the best option to restrict particular urls. I'm totally agreed with raheel that to check server before implementation.
Msg#: 3699828 posted 8:39 pm on Aug 12, 2008 (gmt 0)
I don't see any problem with Googlebot accessing your site via https. You probably have external or internal links to your homepage with 'https' prefix. Having second robots_ssl.txt looks best option if you really need to prevent https... Don't forget Mediapartners-Google. And... don't think that 'access rights' (robots.txt) are really associated with http/https; Google might have some bugs so that it won't crawl http if you restricted https...