A communications device for implementing an electronic payment process, the communications device including a receiver unit operable to receive a secure limited use key (SLUK) from a financial institution that is generated by the financial institution using a first limited use key (LUK) generated using a first key associated with the financial institution, an identifier which identifies a user of the communications device, and a variable code, and a subset of the characters of a passcode associated with the user of the communications device, each character in the subset being identified by its character position in the passcode, and the character position in the passcode of each of the characters in the subset being determined by a predetermined algorithm on the basis of a second key associated with the user of the communications device, the identifier which identifies the user of the communications device and the variable code.