https - Are there any disadvantages to using a 4096-bit encrypted SSL certificate?

Question

I was recently requesting a SSL cert via GoDaddy and noticed this message:

In the past I have always generated 2048-bit CSR requests, but this time it got me thinking that perhaps I should "step it up," and it seems like the next step would be a 4096-bit version.

There isn't much info available on 4096-bit SSL certs - but apparently many people have been using 1024-bit certificates until they absolutely had to upgrade and now some browsers won't support the 1024-bit certificates anymore.

How is browser support for 4096-bit certificates? If GoDaddy requires "at least" a 2048-bit certificate, is that enough, or should I try and do something more? If so, what are the advantages and disadvantages?

PS: the two links in GoDaddy's message are CSR Help and Learn more, neither of which I found very helpful.

Answer 1

Pretty much all* browsers will support 4096-bit keys. The issue you'll run into is that key exchange is slower with larger keys, which will increase load on the server and slow down page loading on the client.

2048-bit keys are generally considered safe for the time being. If you want an intermediate step, though, 3072-bit keys are right smack-dab in the middle.

*: Only exception might be a couple of weird, old mobile / embedded browsers.