The NSA's public relations office led the revamping of CryptoKids, says Don Weber, a representative for the agency. But in creating it, PR specialists turned to “subject matter experts, both military and civilian, throughout the Agency,” says Jane Hudgins, another NSA spokesperson. (The agency declined to make any such experts available for interviews.) To ensure that children with varying backgrounds and levels of education would be interested in the site, Hudgins says, the NSA held focus groups with hundreds of children, teachers, and parents.

Traffic at CryptoKids fluctuates depending on “heightened public awareness [of NSA] or announcements of new initiatives, events, or releases of previously declassified information,” Hudgins says. Still, CryptoKids is consistently the second-most-visited section of the NSA's website, surpassed only by the careers section.

There are several other online destinations as well for children interested in sending and reading secret messages. Cryptoclub was designed by mathematicians at the University of Illinois at Chicago to teach kids about ciphers. The site is a companion to an upcoming children's book, Cryptography: the Mathematics of Secret Codes. Janet Beissinger, a mathematician at the Institute for Mathematics and Science Education at the university, wrote the book with colleague Vera Pless. Beissinger says kids are naturally drawn to secret messages, and since techniques for making and breaking ciphers are mathematical in nature, cryptology is an excellent way to incorporate some math lessons.

“What we realized is that there are a lot of interesting things you can do with ciphers that are too tedious to do by hand,” such as counting the frequencies of letters in a long cipher message, says Beissinger. “The main goal is to use the computer as a tool...the computer does the tedious work and the kids do the thinking.”

Cryptoclub helps its visitors create their own ciphers or crack an old one, called Vigenère, once thought to be unbreakable by Civil War military officers. “You can actually break it using middle-grade mathematics,” Beissinger explains. She says the method entails looking for repeating letter patterns, figuring out how far apart those occurrences are, and finding the common factors between distances of these recurrences.

Beissinger believes that the NSA kids’ site has a good user interface, but that its cipher activities could be more rigorous. “The computer is a powerful tool,” she says, adding that CryptoKids doesn’t fully exploit the computer's ability to help make and break more complicated ciphers.

Perhaps the NSA is wary of inadvertently spawning a new generation of computer criminals as it attempts to heighten children's interest in cryptography. Certainly, given the recent spate of headlines about the agency’s controversial domestic wiretapping activities, its recruiting appeal to children will attract more public attention.