Typically, an attacker will know he's guessed wrong because the decrypted results will be unintelligible. If Honey Encryption has been used, however, the wrong guess will generate phony results that appear to be genuine. Because each incorrect guess generates a plausible result, it will be difficult for the attacker to know when he has guessed correctly.
Honey Encryption was created by Ari Juels, former chief scientist of the RSA, and Thomas Ristenpart from the University of Wisconsin. At the time of this writing, Honey Encryption is best-suited for constructions in which encrypted data is derived from passwords.