Digital content encryption and decryption method and workflow system using digital content

摘要

Disclosure of information is controlled selectively depending on users such that a plurality of users having different roles bearing no inclusive relation with one another can access the same area. Content is divided into a plurality of areas. For each of the areas obtained by division, secret keys (encryption/decryption keys in symmetric-key cryptography) are generated. The generated keys are encrypted using public keys in public-key cryptography, which are set in advance for the users depending on their respective roles. In the case where the content is to be disclosed to a plurality of users having different roles, the encryption of secret keys is performed separately for each user. These encrypted contents and encrypted secret keys are used to generate encrypted text.