Telecommunication Security (Telesec) is a value-added service for the encryption offiles
. Telesec works with a personal chip card with which the user can electronically sign his documents or files according to the asymmetric cryptographic encryption method, the RSA method
, and encrypt them with theDES algorithm
. In 1991, the development projects Telesec-Fax, for protected fax file transfer, and Telesec-Voice, for confidential telephoning, were introduced in ISDN. Telesec is a trademark of Deutsche Telekom.