A method for a secure electronic signature of information of a payment or online banking transaction originating from a server, with a mobile personal signature device, wherein the signature device is comprising: - at least one display to display information, - an integrated smart card or a connecting means for a smart card that is designed in such a way that the smart card is permanently integrated, wherein the personal mobile device, smart card and display form a small, compact, portable modular unit which the user has under his control; - an input unit for interaction; - an interface, which allows a detachable connection at different locations, which can be used for the signature of information in different places, over which the information to be signed are received, and over which the signed information is returned; - with a controller, being configured and adapted to display only information on the displays that are decrypted by the smart card and thus intended for a specific user ID, which is determined by the smart card, a signature action referring to the displayed information obligatory requests an input by the input unit; - a power supply which is provided via the interface or a built-in battery; comprising the steps of: - connecting the mobile personal signature device via the interface with a PC or a cash register, which in turn are connected to a server, so that the mobile personal signature device can receive information from the server; - inputting the information to be signed of the payment or online banking transaction on the PC or the cash register; - transmitting of the information to the server, that changes the information in a way so that they can be decrypted by the smart card with the specific user ID; - sending the encrypted information by the server to the mobile personal signature device; - receiving of the encrypted information of the PC or the cash register when the information is encrypted correctly; - displaying the information on the display and waiting for an approval by the user; - after an input by the user on the input unit signing the information for release by the mobile personal signature device and sending the information to the server that is executing the transaction if the signature is correct. - at least one display to display information, - an integrated smart card or a connecting means for a smart card that is designed in such a way that the smart card is permanently integrated, wherein the personal mobile device, smart card and display form a small, compact, portable modular unit which the user has under his control; - an input unit for interaction; - an interface, which allows a detachable connection at different locations, which can be used for the signature of information in different places, over which the information to be signed are received, and over which the signed information is returned; - with a controller, being configured and adapted to display only information on the displays that are decrypted by the smart card and thus intended for a specific user ID, which is determined by the smart card, a signature action referring to the displayed information obligatory requests an input by the input unit; - a power supply which is provided via the interface or a built-in battery; comprising the steps of: - connecting the mobile personal signature device via the interface with a PC or a cash register, which in turn are connected to a server, so that the mobile personal signature device can receive information from the server; - inputting the information to be signed of the payment or online banking transaction on the PC or the cash register; - transmitting of the information to the server, that changes the information in a way so that they can be decrypted by the smart card with the specific user ID; - sending the encrypted information by the server to the mobile personal signature device; - receiving of the encrypted information of the PC or the cash register when the information is encrypted correctly; - displaying the information on the display and waiting for an approval by the user; - after an input by the user on the input unit signing the information for release by the mobile personal signature device and sending the information to the server that is executing the transaction if the signature is correct.