Security system protecting data with an encryption key

Details Security system protecting data with an encryption key Security system protecting data with an encryption key

1999-10-07

2001-08-28

Swann, Tod (Department: 2132)

Electrical computers and digital processing systems: support

Data processing protection using cryptography

By stored data protection

C713S185000, C380S281000, C380S283000

Reexamination Certificate

active

06282651

ABSTRACT:

BACKGROUND OF THE INVENTION
This invention relates to a method of protecting information stored in a memory device such as an EPROM.
The manufacturers of Digital Signal Processors (DSPs), as a service to their customers, will manufacture the DSP to operate with the customer's own proprietary programs. As a part of that service, the manufacturers attempt to protect the customer's proprietary information. In some cases, the proprietary information is stored external to the DSP in memories such as EPROMs, masked ROMs, CDs and even floppy discs. The DSPs are mass produced and are not unique to any particular customer. Any customer may develop a program to run on the DSP by using the DSP's unique OP-Codes. The concern that a customer has is that, after a substantial investment in time and money developing a proprietary program, a competitor or even a program pirate may obtain his program by purchasing a copy of it and a DSP and then extracting the program.
One way of protecting proprietary programs is to encrypt them prior to their being read. U.S. Pat. No. 4,764,959 disclosed a single-chip microcomputer with an encryption function that encrypts the contents of the memory for secrecy protection when the programs stored in a Read Only Memory (ROM) are read to the outside. However, it is quite simple to reverse engineer the ROM and determine the program by observing the state of each memory cell of the ROM.
Smart Card manufacturers also have developed many techniques for authenticating (a form of encryption) the validity of data stored in a smart card's memory. For example, U.S. Pat. No. 5,343,530 disclosed one method.
SUMMARY OF THE INVENTION
Proprietary information such as programs and/or data are protected using a secure processing system that includes a memory, such as an EPROM, in which the proprietary information is stored in a first portion of the memory. The stored information is encrypted by an encryption algorithm unique to the proprietor of the information. The stored information is assigned an unique key that will enable the information to be decrypted if the unique algorithm is known. A second portion of the memory has the unique key stored therein. The unique key is encrypted with a master encryption algorithm and can only be obtained by using a master key with the master algorithm. A processing unit such as a Digital Signal Processor (DSP) has both the proprietor's unique algorithm, master algorithm and master key available to it. The processing unit can retrieve the information from the memory and execute it after decrypting the unique key using the master algorithm and the master key and then decrypting the information using the unique algorithm and the unique key.
The processing unit has an access port for accessing the information stored in the memory unit. A second processing unit, such as a personal computer, can be connected to the access port and an operator can enter the unique key. The second processing unit can then retrieve the encrypted information by providing the DSP with the unique key. The DSP will decipher the encrypted information using the proprietary algorithm and the unique key and then passes the decrypted programs and/or data to the second processing unit.
For security purposes, the master program is very complex but the unique algorithm is less complex than the master algorithm.
The security system may also be used for smart cards. A smart card provider will have its own proprietary algorithm and key and each card holder will have their own unique key and algorithm such as a Personal Identification Number (PIN). The card holder will enter his card into a DSP device such as a cash machine and enter his PIN in the machine. The smart card has the PIN that has been encrypted by a master algorithm stored in a portion of the memory of the smart card. The DSP retrieves and deciphers the encrypted PIN and compares it to the PIN that the card holder had entered. If the comparison is correct, then the data stored in the smart card is transferred and deciphered in the manner discussed above. The card holder can then carry out the desired transaction.


REFERENCES:
patent: 5142578 (1992-08-01), Matyas et al.
patent: 5894516 (1999-04-01), Brandenburg
patent: 5999629 (1999-12-01), Heer et al.
patent: 6014745 (2000-01-01), Ashe
patent: 6069957 (2000-05-01), Richards

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