An ancient sorcerer's recipe for potions and cures, straight out of a Harry Potter adventure? An unbreakable secret code? Some message from a lost civilization -- or another planet?

Those tantalizing explanations for the fabled Voynich manuscript -- sometimes termed "the world's most mysterious book" -- may give way to a more humdrum scenario.

British computer scientists have concluded that the so-called VM, which has stumped generations of scientists, is a scam concocted 400 years ago by an Elizabethan con artist to bilk a king.

In a new study, they describe how secret coding, or cryptographic, techniques available in the late 1500s could produce the VM's strange text. Although invented to change text into secret code, the methods also can be used to generate gibberish for a hoax.

"The hoax hypothesis is now a plausible explanation for the Voynich manuscript," Dr. Gordon Rugg said in an interview from Keele University in England. He headed the study and provided an advance copy of the report, which will be published in the January 2004 edition of "Cryptologia." Cyrptology researchers often announce new discoveries in the noted journal.

International experts on the VM both praised and criticized Rugg's conclusions. Some cited the need for follow-up studies to rule out other explanations for the VM's unique script, text, and images.

Now a prized holding in Yale University's Beinecke Rare Book and Manuscript Library (beinecke.library.yale.edu/dl_crosscollex/), the VM reads like a book from Mars.

About 6-inches by 9-inches, it contains more than 230 pages written in neat, clear script in an unknown language. There's no punctuation or indication of sentences. Its parchment leaves and foldouts are richly illustrated with individually captioned watercolor images of apparent medicinal plants not found on Earth. Other images show apparent astrological signs or constellations of stars unknown to science; oddly proportioned naked women; and complex systems of plumbing-like tubes carrying liquids.

"We have no clear idea of its date, its author, its provenance, the meaning of its script, or even the meaning of its drawings," said Jim Gillogly, a former RAND Corporation researcher who administers a Web site (www.voynich.net) devoted to VM research.

The Holy Roman Emperor Rudolf II, who reigned from 1576-1612, was the VM's first known owner. He bought it from an unknown seller for coins that contained more than 7 pounds of pure gold. Rare book dealer Wilfrid M. Voynich bought it in Italy around 1912, and it later passed to another book dealer, Hans P. Kraus, who valued it at $160,000. Unable to find a buyer, Kraus donated the VM to Yale's rare book collection in 1969.

Yale describes the VM as a "scientific or magical text in an unidentified language." One hypothesis suggests that it was the coded personal notebook of a medieval alchemist. Those forebearers of the modern chemist tried to make a powder, called the "philosopher's stone," that would cure all illnesses, prolong life, and change lead into gold.

Others suggest that it was written in some lost language or secret code developed by 13th century scholar Roger Bacon.

The world's best code-breakers, however, have been unable to verifiably decipher a single word of the text. The VM's content likewise has befuddled linguists, botanists, mathematicians, astronomers, historians, astrologers, and crackpots for more than a century.

Rugg began research on the VM because he thought it could be the key to a more secure code.

"Codes are at the heart of modern security systems," he explained. "When I started work on this project, there was a real possibility that some Renaissance genius had invented a type of code which our best code breakers couldn't crack. That was too tantalizing a possibility to ignore."

Modern researchers have cracked every other early coding system within a few days, he noted.

David Kahn considered and rejected the hoax alternative in his 1976 book ("The Codebreakers") on secret communications.

"Is it, then, just a gigantic hoax, like the Cardiff giant or the Piltdown man?" Kahn asked of the VM. "The work is too well organized, too extensive, too homogeneous. Moreover, the words in the text recur, but in different combinations, just as in ordinary writing. Even if it was a hoax, there seems to be no point to having made it so long."

Rugg said most VM researches abandoned the hoax hypothesis years ago for exactly those reasons.

"The manuscript exhibits so much linguistic structure that a hoax appears to require almost as much sophistication as an unbreakable code," he explained. "It has been generally assumed that a hoax showing these features would take an enormous amount of time to generate, and would not be economically viable for a hoax perpetrated for financial gain, even if it was technically possible."

Rugg's study details how one person could have used 16th coding technology to generate the VM's entire text within two to three months. The illustrations could have been inserted quickly, as well. And the point may have been a swindle.

"It would have brought him a lot of money," Rugg said, noting the small fortune that Rudolph II shelled out. "There also may have been an element of vanity involved -- tricking the leading scholars of the day."

Rugg thinks the con artist probably was Edward Kelley, an Elizabethan adventurer involved in many dubious activities, who once worked with an associate to invent a language called Enochian. Kelley allegedly produced gold using alchemy, claimed to be clairvoyant, and once was imprisoned for fraud.

Gillogly, like several other VM researchers, described the hoax hypothesis as sound.

"I applaud his work," he said, noting that Rugg's coding approach did produce text similar to the VM. But Gillogly said it would take more evidence to clinch the case, such as using Rugg's technique to produce a specific page of the VM.

Others disagreed.

"To me, it is evident that Gordon Rugg has made his conclusions according to his beliefs and not on substantiated facts," said John Stojko, a New Jersey engineer who claims to have deciphered the VM almost 30 years ago.

Stojko's research concluded that the VM is not gibberish or secret code, but ancient writing in a script that marked humanity's transition from the picture writing of hieroglyphics to modern alphabets. His 1978 book ("Letters to God's Eye") offered a translation into English, depicting the VM as the saga of a religious or civil war in what now is the Ukraine.