DNA Technique Protects Against ‘Evil’ Emails
A technique originally designed to analyze DNA sequences is the latest weapon in the war against spam. An algorithm named Chung-Kwei (after a feng-shui talisman that protects the home against evil spirits) can catch nearly 97 per cent of spam.
Chung-Kwei is based on the Teiresias algorithm, developed by the bioinformatics research group at IBM’s Thomas J Watson Research Center in New York, US. Teiresias was designed to search different DNA and amino acid sequences for recurring patterns, which often indicate genetic structures that have an important role.
Instead of chains of characters representing DNA sequences, the research group fed the algorithm 65,000 examples of known spam. Each email was treated as a long, DNA-like chain of characters. Teiresias identified six million recurring patterns in this collection, such as “Viagra”.
Each pattern represented a common sequence of letters and numbers that had appeared in more than one unsolicited message. The researchers then ran a collection of known non-spam (dubbed “ham”) through the same process, and removed the patterns that occurred in both groups.
Incoming email was given a score based on how many spam patterns it had. A long email that only had a few spammy sentences would get a relatively low score; but one with many patterns spread across the length of the message would score much higher. The Chung-Kwei correctly identified 64,665 of 66,697 test messages as being spam or 96.56 per cent.
Chung-Kwei deals with common spammer strategies to dodge pattern-recognition schemes, such as replacing the s with a $, as in “increa$e your $ex power” using its built-in tolerance for different, but functionally equivalent, DNA sequences.
Just as in genetic analysis, Teiresias could be taught that CCC and CCU codons both produce the same amino acid, proline, the anti-spam system can be trained to accept $ and s as identical.
IBM intends to include Chung-Kwei in its commercial product, SpamGuru. Justin Mason, who developed SpamAssassin, one of the most popular open-source anti-spam filters, says that Chung-Kwei looks promising.
“I think there is still a lot of work to be done. But what is exciting is not the particular algorithm, but the fact that IBM has shown there is the entire field of bioinformatics techniques to explore in the fight against spam.