The invention provides an authentication method and system. It is particularly suited for verifying the identity of an individual prior to permitting access to a controlled resource. This may or may not be a financial resource. The invention uses biometric data relating to a user to encode and decode an identifier associated with a user. Thus the user's biometric data becomes the key for encoding and subsequently decoding the identifier. In one embodiment, the biometric data is used to generate a keypad configuration. The keypad configuration specifies the order and/or position of a plurality of keypad keys. An operable keypad and/or image of a keypad is then generated using the configuration. Thus, the individual's biometric data can be used to generate a customised keypad and/or image which can then be used to encode or decode the identifier associated with the user. A keypad or image generated from the biometric data can be used to generate a mapping between different keypad configurations. The biometric data may be captured at or on a device associated with the individual, such as a computer, mobile phone, tablet computer etc.