Anyone with a moderate amount of skill can intercept Internet mail messages and private web pages to see what they say; can modify messages in transit, changing their content without any trace; and can send fake messages that are indistinguishable from legitimate messages. Cryptography responds to these threats by scrambling and unscrambling packets to protect against forgery and against espionage. An attacker who forges a message can't scramble it in the right way; when legitimate users' computers unscramble the message, they see that it's a forgery and that it should be thrown away. An attacker who intercepts a scrambled credit-card number can't figure out the original number.
Unfortunately, cryptography is often too slow to deploy on busy network servers. Widely used web sites such as google.com and livejournal.com have installed all the necessary cryptographic software but use it for only a small fraction of their web pages.
When a user tells his web browser to make a cryptographically protected connection to https://www.google.com, Google redirects the browser to http://www.google.com, turning off the cryptography!
Similar comments apply to SMTP (mail), DNS (name lookup), and other Internet protocols: even when the necessary cryptographic software has been written and installed, users are often forced to disable or limit the software so that their computers are not overloaded. This research responds by producing new speed records for the cryptographic operations needed to protect the Internet. These speedups allow cryptography to handle a larger fraction of the total volume of Internet communication, reducing the Internet's overall exposure to attack.
CT-ISG: High-Speed Cryptography