Signing messages with digital signature

摘要

The method involves transmitting a message to be signed via a telephone network to a signing device. The signing device is a mobile radiotelephone. The message is signed, and transmitted back to a receiver as a signed messaged. A public key procedure is used for the signing. The messages are transmitted using the Short Message Service (SMS). A secret key may be entered via the telephone key-pad. - DETAILED DESCRIPTION - DETAILED DISCRIPTION - Also claimed are a mobile telephone and a chip card.