Crypto microprocessor that executes enciphered programs

• US 4,465,901 A
• Filed: 07/02/1981
• Issued: 08/14/1984
• Est. Priority Date: 06/04/1979
• Status: Expired due to Fees

• Current Assignee: Dallas Semiconductor Corporation (Analog Devices, Inc.)
• Original Assignee: Robert M. Best
• Inventors: Best, Robert M.
• Primary Examiner(s): Buczinski, S. C.
• Application Number:
  US06/279,833
• Time in Patent Office: 1,139 Days
• Field of Search: 200/61.08, 364/200, 178/22.08, 178/22.09
• US Class Current: 713/190
• CPC Class Codes: G06F 12/1408 by using cryptography for digital transmission H04L9/00
• CPC Class Codes: G06F 21/123 by using dedicated hardware, e.g. dongles, smart cards, cryptographic processors, global positioning systems [GPS] devices
• CPC Class Codes: G06F 21/72 in cryptographic circuits
• CPC Class Codes: G06F 21/75 by inhibiting the analysis of circuitry or operation

Abstract

A microprocessor for executing computer programs which are stored in cipher to prevent software piracy. Such a crypto-microprocessor deciphers the enciphered program piecemeal as it executes it, so that a large enciphered program can be securely executed without disclosing the deciphered program or associated data to persons who have access to the wiring of the computer in which the crypto-microprocessor is a component. Such a device may process valuable proprietary programs and data files which are distributed in cipher on videodiscs, semiconductor memory, or other media without risk of software piracy. Various methods of encryption may be used including methods which result in the cipher of a byte being a complicated function of the byte'"'"'s address in memory. Each crypto-microprocessor chip may use a unique cipher key or tables for deciphering the program, so that a program that can be executed in one chip cannot be run in any other microprocessor.

Claims

1. A method of protecting a program of executable instructions during execution, comprising the steps of:

storing said program in enciphered form as a plurality of addressable portions;

generating a digital address for addressing a portion of said enciphered program;

cryptographically scrambling together said addressed portion and said digital address to produce an executable portion of an instruction in said program;

executing said instruction; and

addressing a subsequent portion of said enciphered program in accordance with said executed instruction.

2. A cryptographic microprocessor apparatus constructed as an integrated circuit chip for executing a computer program of instructions received from a digital radio broadcast in enciphered form as a plurality of portions of enciphered information, the apparatus comprising:

means for addressably storing a plurality of portions of said enciphered information received from a digital radio broadcast;

means in said chip for storing a cipher key;

deciphering means in said chip for cryptographically transforming a portion of said enciphered information under control of said cipher key to produce a portion of deciphered information;

means in said chip for executing an instruction from a portion of said deciphered information; and

means in said chip for addressing a successor portion of said enciphered information in said storing means for deciphering by said deciphering means.

3. A cryptographic microprocessor system for executing computer programs of instructions stored in enciphered form on a record carrier means as a plurality of portions of enciphered information, the system comprising:

means for initiating reading of a portion of said enciphered information from said record carrier means;

memory means for storing a portion of said enciphered information at a storage means location specified by a digital address;

means for deciphering a portion of said enciphered information as a cryptographic function of its digital address to produce a portion of deciphered information;

means for executing an instruction from said portion of deciphered information; and

means for addressing a successor portion of said enciphered information for deciphering by said deciphering means.

4. The system of claim 3, wherein said record carrier means is a disc-shaped body having an information bearing structure arranged in concentric tracks.

5. A cryptographic microprocessor system for executing computer programs of instructions stored in enciphered form on a record carrier means as a plurality of portions of enciphered information, the system comprising:

means for initiating reading of a portion of said enciphered information from said record carrier means;

memory means for addressably storing said portion of enciphered information;

means for storing a cipher key;

means for deciphering a portion of said enciphered information under control of said cipher key to produce a portion of deciphered information;

means for executing an instruction from said portion of deciphered information; and

means for addressing a successor portion of said enciphered information in said storing means for deciphering by said deciphering means.

6. The system of claim 5, wherein said record carrier means is a disc-shaped body having an information bearing structure arranged in concentric tracks.

7. The system of claim 6, further comprising said disc-shaped body.

8. A cryptographic microprocessor system for executing computer programs of instructions stored in enciphered form on a record carrier means as a plurality of portions of enciphered information, the system comprising:

means for initiating reading of a portion of said enciphered information from said record carrier means;

memory means for storing said portion of enciphered information at a storage means location specified by a digital address; and

cryptographic microprocessor means for deciphering a portion of said enciphered information as a cryptographic function of its digital address to produce a portion of deciphered information, and for executing an instruction from said portion of deciphered information, and for addressing a successor portion of said enciphered information for deciphering.

9. A cryptographic microprocessor system for executing computer programs of instructions stored in enciphered form as addressable portions of enciphered program information, the system comprising:

means for specifying the digital address of a portion of said enciphered program information;

means for deciphering said addressed portion of enciphered program information as a cryptographic function of said digital address to produce a portion of deciphered information containing an executable portion of an instruction; and

microprocessor means for executing said instruction and for addressing a success portion of said enciphered program information for deciphering by said deciphering means.

10. A cryptographic microprocessor system for executing computer programs of instructions stored in enciphered form as addressable portions of enciphered program information, the system comprising:

means for specifying the digital address of a portion of said enciphered program information;

means for storing a cipher key;

means for deciphering said addressed portion of enciphered program information as a function of said digital address and under control of said cipher key to produce a portion of deciphered information containing an executable portion of an instruction; and

microprocessor means for executing said instruction and for addressing a successor portion of said enciphered program information for deciphering by said deciphering means.

11. A cryptographic microprocessor system for executing computer programs of instructions stored in enciphered form on a record carrier means as a plurality of portions of enciphered information, the system comprising:

memory means for addressably storing a plurality of portions of said enciphered information, the location of each portion being specified by a digital address;

means for storing a cipher key;

means for deciphering a portion of said enciphered program information as a function of its digital address and under control of said cipher key to produce a portion of deciphered information containing an executable portion of an instruction; and

microprocessor means for executing said instruction and for addressing a successor portion of said enciphered program information for deciphering by said deciphering means.

12. A cryptographic system of at least two microprocessors for executing computer programs of instructions stored in enciphered form as a plurality of portions of enciphered program information, the system comprising:

memory means for addressably storing a plurality of portions of said enciphered program information;

first microprocessor comprising;

a. means for deciphering a portion of said enciphered program information to produce a portion of deciphered information containing an executable portion of an instruction, and

b. means for executing said instruction and for addressing a successor portion of said enciphered program information for deciphering by said deciphering means;

second microprocessor connected to receive and process information from said first microprocessor; and

bus means connecting said first and second microprocessors for conveying a portion of information between said microprocessors.

13. A cryptographic system of at least two microprocessors for executing computer programs of instructions stored in enciphered form as a plurality of portions of enciphered program information, the system comprising:

memory means for addressably storing a plurality of portions of said enciphered program information;

first microprocessor comprising;

a. means for storing a cipher key,

b. means for deciphering a portion of said enciphered program information under control of said cipher key to produce a portion of deciphered information containing an executable portion of an instruction, and

c. means for executing said instruction and for addressing a successor portion of said enciphered program information for deciphering by said deciphering means;

second microprocessor means connected to receive and process information from said first microprocessor; and

bus means connecting said first and second microprocessors for conveying a portion of information between said microprocessors.

14. A cryptographic system of at least two microprocessors for executing computer programs of instructions stored in enciphered form on a record carrier means as a plurality of portions of enciphered program information, the system comprising:

means of initiating reading of a portion of said enciphered program information from said record carrier means;

memory means for addressably storing a plurality of portions of said enciphered program information read from said record carrier means;

first microprocessor comprising;

a. means for storing a cipher key,

b. means for deciphering a portion of said enciphered program information under control of said cipher key to produce a portion of deciphered information containing an executable portion of an instruction, and

c. means for executing said instruction and for addressing a successor portion of said enciphered program information for deciphering by said deciphering means;

second microprocessor means connected to receive and process information from said first microprocessor; and

bus means connecting said first and second microprocessors for conveying a portion of information between said microprocessors.

15. The system of claim 14, wherein said record carrier means is a disc-shaped body having an information bearing structure arranged in concentric tracks.

16. A cryptographic microprocessor apparatus for executing computer programs of instructions stored in enciphered form as addressable portions of enciphered information, the sytem comprising:

means for storing a plurality of cipher keys;

means for selecting a deciphering key from said plurality of cipher keys;

means for deciphering a portion of said enriched information under control of said deciphering key to produce a portion of deciphered program information;

means for executing an instruction from said portion of deciphered program information; and

means for addressing a successor portion of said enciphered information for deciphering by said deciphering means.

17. A cryptographic microprocessor apparatus for executing computer programs of instructions stored in enciphered form as addressable portions of enciphered information, the system comprising:

means for specifying the digital address of a portion of said enciphered information;

means for storing a plurality of cipher keys;

means for selecting a deciphering key from said plurality of cipher keys;

means for deciphering said addressed portion of enciphered information as a function of said digital address under control of said deciphering key to produce a portion of deciphered program information;

means for executing an instruction from said portion of deciphered program information; and

means for addressing a successor portion of said enciphered information for deciphering by said deciphering means.

18. A cryptographic microprocessor system for executing computer programs of instructions stored in enciphered form on a record carrier means as a plurality of portions of enciphered information, the system comprising:

means for initiating reading of a portion of said enciphered information from said record carrier means;

memory means for addressably storing said portion of enciphered information;

means for storing a plurality of cipher keys;

means for selecting a deciphering key from said plurality of cipher keys;

means for deciphering a portion of said enciphered information under control of said deciphering key to produce a portion of deciphered information;

means for executing an instruction from said portion of deciphered information; and

means for addressing a successor portion of said enciphered information in said memory means for deciphering by said deciphering means.

19. A method of protecting a computer program of executable instructions, comprising the steps of:

storing said program in enciphered form as a plurality of addressable bytes;

generating an address for addressing a byte in said program;

cryptographically combining said addressed byte with said address to produce a deciphered operation code;

executing an instruction in said program which includes said deciphered operation code; and

addressing a subsequent byte in said program in accordance with said executed instruction.

20. A cryptographic microprocessor for executing a computer program of instructions stored in enciphered form as a plurality of addressable portions of enciphered program information, each addressable portion having a digital address, the apparatus comprising:

means for addressing a portion of said enciphered program information;

deciphering means for cryptographically combining said addressed portion of information with the digital address of the addressed portion and for cryptographically transforming the addressed portion to produce a deciphered operation code in said program;

processing means for decoding said deciphered operation code, and for executing the decoded operation code, and for addressing a subsequent portion of said enciphered program information for transforming by said deciphering means.

21. The apparatus of claim 20, wherein every bit in said deciphered operation code is a function of at least four bits in said digital address.

22. A cryptographic microprocessor apparatus for executing computer programs of instructions addressably stored in enciphered form as portions of enciphered program information, the apparatus comprising:

deciphering means for cryptographically transforming a portion of said enciphered program information to produce a deciphered instruction in a program;

processing means for executing said deciphered instruction to produce an address of a successor instruction; and

means for addressing a portion of said addressably stored enciphered information which contains said successor instruction in enciphered form and which said deciphering means transforms to deciphered form.

23. The apparatus of claim 22, wherein said portions of enciphered program information are received from a digital broadcast of electro-magnetic radiation such as a radio broadcast.

24. The apparatus of claim 22 further comprising means for reading portions of said enciphered information from a disc-shaped record carrier means.

25. A cryptographic microprocessor apparatus for executing computer programs of instructions stored in enciphered form as addressable portions of enciphered program information, each portion being stored at a memory location specified by a digital address, the apparatus comprising:

addressing means for specifying the digital address of a portion of said enciphered program information;

deciphering means for cryptographically transforming said addressed portion of information as a function of said specified digital address to produce a deciphered instruction in a program; and

processing means for executing said deciphered instruction to produce an address of a successor instruction, said addressing means further addressing a portion of said enciphered program information which contains said successor instruction in enciphered form.

26. In an improved microprocessor apparatus fabricated as an integrated circuit chip having an electrically alterable memory for storing a plurality of executable program instructions and processing circuitry for fetching program instructions from said memory and for executing the fetched instructions and for addressing in said memory successor instructions, and an external conductor for controlling loading of a predetermined number of integers into electrically alterable memory means in said chip, the improvement for protecting program instructions in said chip comprising:

storing means in said chip for storing an indication of a set or reset condition, one condition enabling reading from said memory means and the other condition disabling reading from said memory means;

means in said chip for setting said storing means after said integers are loaded into said memory means;

means in said chip for disabling loading of additional integers into said memory means in response to said storing means storing an indication of a set condition; and

means in said chip for disabling external access to said memory means in response to said storing means storing an indication of a set condition.

27. The apparatus of claim 26, wherein said storing means is set in response to a signal on said external conductor.

28. The apparatus of claim 26, wherein said storing means is set in response to a sequence of codes communicated to said chip.

29. The apparatus of claim 26, further comprising an internal program for loading said electrically alterable memory means.

30. In an improved microprocessor apparatus fabricated as an integrated circuit chip having an electrically alterable memory for storing a plurality of executable program instructions and processing circuitry for fetching program instructions from said memory and for executing the fetched instructions and for addressing successor instructions in said memory, and an external conductor for controlling loading of a predetermined number of integers into electrically alterable memory means in said chip, the improvement for protecting program instructions in said chip comprising:

setable means in said chip having either a set state or a reset state, one state enabling reading from said memory means;

means in said chip for setting said setable means after said integers are loaded into said memory means and in response to bits input on said external conductor;

means in said chip for disabling subsequent commands in response to the state of said setable means; and

means in said chip for disabling external access to said memory means in response to the state of said setable means.