Electronic sealed envelope

摘要

Restricted data is stored on a smart card having a memory and a processor. Preferably the restricted data is stored in groups. The smart card may store a record of users authorized to access certain groups of restricted data. An owner of the smart card must authorize registration of new users by entering their password, the new users are then given their own passwords in order to retrieve certain groups of restricted data. When a registered user uses their password to retrieve restricted data the smart card irretrievably modifies a codeword in a codeword section of the restricted data group, each codeword corresponding to an authorized user. The owner of the smart card is then able to determine if the restricted data has been accessed by checking for modified codewords.