The author said she was targeted by “fake emails” from “cyber criminals”, who were trying to obtain the unpublished book.
Atwood told the BBC the attempts were a “phishing exercise” that could have resulted in blackmail or identity theft.
“It was a commercial venture of a robbery kind,” she said.
Atwood added: “People were trying to steal it. Really, they were trying to steal it and we had to use a lot of code words and passwords.
“What would they have done with it if they had succeeded? They might have said, ‘We’ve got the manuscript, and we’re putting it up online [unless you] give us your credit card details.’ Or they might have said, ‘Read this excerpt and download it. And if you downloaded it, a virus would have stolen your information.’
“Think of how terrible we all would have felt had that happened.”
In order to protect the manuscript, reports the BBC, early review copies were issued under a different title and Booker Prize judges were required to sign a non-disclosure agreement before they could read watermarked manuscripts that were locked in drawers overnight.
Despite all of these precautions being taken, Amazon accidentally sent out pre-ordered copies of The Testaments a week early.
The online retail giant said a “technical error” had caused some US customers to be “inadvertently sent copies”.
The Testaments is out on 10 September
Join our new commenting forum
Join thought-provoking conversations, follow other Independent readers and see their replies