On 12/20/2012 10:30 AM, Viktor Dukhovni wrote:
We could follow the herd and recommend 2048 bits, since SMTP servers rarely do enough RSA-ops for RSA performance to be a bottleneck. On the other-hand, for people wielding self-signed certs almost certainly 1024 is plenty strong at 2^80, and 1280 raises this a notch to 2^89 with a much lower performance penaly than RSA 2048 (whose GNFS factoring cost is ~2^112).
I did go back to look and in fact replacing a 1024 cert with a 2048 cert cured 'some' browser issues with self signed certs. I have not seen this make it to any email client yet, but expect it will. I agree that this is a resource waste in most situations, likely all where a self signed cert is used. My point is simply trying to get the future right, so I don't wake up to a morning of customer complaints when the next update to 'no insight' launches. I can't help but wonder if some of these products making it harder to use self signed certs are produced by companies looking at getting into the CA business? More than enough said.
For us, we use self signed certs with our hosting clients for one main reason. We set DNS for mailsystems on their domain name. They can then use something like mail.mydomain.com as their mailserver. We can move them to another server here and not have any affect on their email settings (other than accepting the new cert). We are mainly interested in passing login information using encryption.
-- John Hinton 877-777-1407 ext 502 http://www.ew3d.com Comprehensive Online Solutions
