Method for securely using digital signatures in a commercial cryptographic system

(57) System encoded by being a system for in a summary business ciphering system] using a digital signature safely, and using the attribute proof for carrying out the requirements for a measure and permission of the security countermeasures and permit information covering the industrial world during a signature and proof. The check of the requirements for a measure and permission is carried out in a system by restricting access to a public key to the user who agrees to perform the digital signature and to follow the rule of a system. These rules can also guarantee that payment for use of a public key and a secret key is made. Furthermore, the user can impose his own rule and the requirements for a measure on the transaction in a system.