Patent ID: 7000114

Claim:
A signature creating apparatus which creates and connects a digital signature, said signature creating apparatus comprising: a clock in which time information is set only by an external time authentication authority; an ID storing unit which stores an apparatus ID for specifying the creating apparatus using a form capable of preventing interpolation; a personal identification storing unit which stores personal identification information for specifying a person who has a proper right to update stored contents; a first connecting unit which creates connection data by connecting plain-text, the time information, the apparatus ID, and the personal identification information that identifies a person using the creating apparatus in a predetermined order; a signature creating unit which creates the digital signature using the connection data created by said first connecting unit and a key used only for creating a digital signature; a second connecting unit which creates signed data by connecting the digital signature with the connection data, and a confirming unit which confirms a working state of said clock, wherein the personal identification information is stored within the signature creating apparatus using a form capable of preventing interpolation, the signature creating unit encrypts the connection data to create the digital signature, the second connecting unit outputs the signal data to be transmitted to an external network, said signature creating unit creates the digital signature only when said confirming unit confirms that said clock works normally, stops using the key used only for creating the signature when said confirming unit confirms that said clock does not work normally, and creates an alternate digital signature using connected information which does not include the time information and using a key other than the key used only for creating the signature.