The
Sybil attack in computer security is an attack wherein a
reputation system is subverted by forging identities in
peer-to-peer networks. It is named after the subject of the book
Sybil, a case study of a woman diagnosed with
dissociative identity disorder. The name was suggested in or before 2002 by Brian Zill at
Microsoft Research. The term "pseudospoofing" had previously been coined by L. Detweiler on the Cypherpunks mailing list and used in the literature on peer-to-peer systems for the same class of attacks prior to 2002, but this term did not gain as much influence as "Sybil attack".