The intent of the spammer is to disguise that content in such a way that it cannot be detected and flagged by spam filtering programs.
In this case, the intended recipient of the secret content (names and prices of drugs) is the recipient of the email message. (If you view the raw HTML source text, you see that the characters spell out random words and sentences and the name of the drugs don’t appear anywhere in the text.) In particular, the images of the letters and numbers that appear on the screen are constructed by carefully arranging the positions of very large numbers of very small characters. I have recently been receiving spam messages where the names and the prices of certain drugs are made to appear on the screen using steganographic techniques in conjunction with the rendering of HTML text. The name comes from Johannes Trithemius‘s Steganographia: a treatise on cryptography and steganography disguised as a book on black magic, and is Greek for “hidden writing.”īecause my email address is plastered all over the Internet, I receive an average of about 10,000 spam messages each month. Steganography is the art and science of writing hidden messages in such a way that no one apart from the intended recipient knows of the existence of the message this is in contrast to cryptography, where the existence of the message is clear, but the meaning is obscured. This lesson is about steganography, (hidden writing) which should not be confused with stenography (shorthand).
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