Trunkfield passed on details about one of James Bulger's killers, Jon Venables. He admitted misconduct in a public office earlier this month.
Trunkfield has since resigned from Woodhill prison and Venables is no longer being held there, the court heard. He was jailed for 16 months,.
A prison officer who worked at a jail near Milton Keynes has been jailed for selling information to the Sun newspaper.
Richard Trunkfield, who worked at high security Woodhill prison was sentenced at the Old Bailey.
An inquest jury has ruled that an alleged double killer who was found hanged in a Milton Keynes prison took his own life.