A method for proof of the time and content of transactions in a digital network is described. A digital form is requested by a customer's computer (1) and is transmitted from a bid server (3) to the customer's computer (1) and such contains the network address of a transaction proof server (4). Form data in the form, includes the data required for acceptance of the bid, and are sent to an order acceptance server. The form data are sent from the customer's computer (1) to the transaction proof server (4), and are provided with a digital time specification. A check digit code is generated for the form data and the digital time specification, and this check digit code is encoded with a key to form a time signature. The form data are transmitted from the transaction proof server (4) with the digital time specification and the time signature to the order acceptance server.