User CSK for the realization of personal key management mechanisms and public key certificates CCC members, as well as the formation of electronic signature and encryption of user data and performs the following functions:- Management of user keys (key generation, recording the private key on the NCI and the formation of a request for certificate creation, check the generated certificate, back up the private key, change to protect the private key password, the destruction of the private key to the NCI, the formation and transfer of CSK request blocking certificate forming and transmitting the request for the new certificate);- Access certificates CSK, servers, CSC, other users certificates and CRL (Certificate viewing and SOS of file storage, search for certificates in the file repository and using the protocol the OCSP, certificate status determination by SOS and the protocol the OCSP, checking the validity and integrity of the certificates and etc.);- Protection of user files: signature files, check the file signature, encryption and decryption of files.