Schmidt-Nielsen is one of more than 60 entrants in what's expected to be a four-year to pick a new hashing algorithm that will help lock down the cryptography used by everything from Web-based payment systems to secure e-mail to source-code management tools.

The contest, sponsored by the National Institute of Standards and Technology (NIST), hopes to find a new cryptographic hash algorithm to replace the SHA-2 (Secure Hash Algorithm - 2) algorithm that NIST published eight years ago. The deadline for SHA-3 submissions was Oct. 31, and NIST hopes to cut the field down to 15 or 20 contestants by next August. That's when the hard work of hammering away at the submissions and knocking loose any flaws will really begin.

Schmidt-Nielsen and others are doing their work unpaid, competing mainly for prestige and the thrill of seeing their work analyzed by their peers. "I think it's a ton of fun," said Schmidt-Nielsen, who first got into cryptography at the tender age of 13. "It will be really fascinating to watch my algorithm get completely torn apart."

Also in the running are famous cryptographers such as Bruce Schneier, BT's chief security officer, and Ron Rivest, who invented the widely used MD5 hash algorithm.

But what is a hash algorithm anyway?