Additional overhead of 256 bit vs 128 bit SSL

[AgentZap]

I've heard in the past that there is a performance cost associated with running a website with a 256 bit certificate vs a 128 bit one. Does anyone know of any good articles or whitepapers on the subject? Thanks

 

[Chiefcrowe]

I too am curious about this.....

 

[Zugzwang152]

Googling found this:
http://www.cs.ucr.edu/~bhuyan/papers/ssl.pdf

There's some nice tables starting on page 6 that gives you what you want. They do comparisons for 128-bit AES vs. 256-bit AES, DES (56-bit) vs. 3DES (168-bit), 512-bit RSA vs. 1024-bit RSA, and MD5 vs. SHA-1.

Interesting tidbit from their conclusion:
70% of the processing time of an HTTPS transaction is spent doing SSL processing.