Anti-fraud measures in relation to cheques

A cheque 10 carries visible markings 12-30 representing cheque data in natural language comprising details of a payment to be made to a payee, and a computer readable marking 34 representing validation data comprising selected cheque data. The validation data is encrypted by a key constructed from key generation data comprising cheque data represented in the visible markings. The key may be a hashed version of the key generation data. The validation data may comprise a sum payable 30, a payee name 24, and a cheque serial number 18. The computer-readable marking may be in the form of a response code or a QR code (RTM). The cheque may be analysed by digitally imaging the cheque, machine reading the visible markings from the image to obtain cheque data from which the key generation data is selected, and determining the key from the key generation data. The computer-readable marking may then be read and its content decrypted by use of the key to obtain the validation data, which is then compared with the cheque data to detect mismatches between them. Except for the payee name, the validation data may be truncated if it exceeds a predetermined length.