Computer software security system
Cryptographic decoder for computer programs
Software protection system
Solid state key for controlling access to computer software
Method and device for protecting software delivered to a user by a supplier
Software protection system with trial period usage code and unlimited use unlocking code both recorded on program storage media Patent #: 4740890
ApplicationNo. 855169 filed on 03/20/1992
US Classes:713/187, COMPUTER PROGRAM MODIFICATION DETECTION BY CRYPTOGRAPHY380/28PARTICULAR ALGORITHMIC FUNCTION ENCODING
ExaminersPrimary: Buczinski, Stephen C.
Attorney, Agent or Firm
Foreign Patent References
International ClassesH04L 009/00
Foreign Application Priority Data1987-02-23 DE
AbstractFor securing programs contained in a system storage and for checking their integrity, the programs are in each case coded by a symmetric cryptographic algorithm with the application of a readback secured, secret key, and a check number for each program is simultaneously formed and stored in the storage of the system. For checking the integrity, the programs are then coded again in the same manner and the check number thus obtained in each case is compared with the check number stored at the first coding. It is possible to derive from the result of comparison a criteria for activation or locking the following programs.
Field of SearchPARTICULAR ALGORITHMIC FUNCTION ENCODING