If you can extract computing power out of IP checksums, you should be able to extract <i>a lot more</i> from cryptographic handshakes, like say SSL. Is this SHA1 valid? Let’s ask Amazon.com. (Actually I think they run an MD5 variant of SSL, but you get the point.)<p>However, you might get your IP blacklisted pretty quickly if you fail the SSL handshake too many times. SSL used to be pretty CPU heavy especially in the old days, so there are bound to be some DoS preventing load-balancers in front of the SSL ports.<p>The biggest problem here of course is that the marginal cost of CPU cycles is quite lower than bandwidth (which is why web servers support GZIP/Deflate for resources). This scheme mostly allows us to convert bandwidth to processing power. I wonder how this ties back to the age-old memory vs. processing trade-off.