|Publication number||USRE40694 E1|
|Application number||US 11/016,685|
|Publication date||Mar 31, 2009|
|Filing date||Dec 20, 2004|
|Priority date||May 31, 1994|
|Also published as||CN1100419C, CN1222274A, DE19781707B4, DE19781707T0, DE19781707T1, US5805706, WO1997039552A1|
|Publication number||016685, 11016685, US RE40694 E1, US RE40694E1, US-E1-RE40694, USRE40694 E1, USRE40694E1|
|Inventors||Derek L. Davis|
|Original Assignee||Intel Corporation|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (8), Non-Patent Citations (2), Referenced by (4), Classifications (9)|
|External Links: USPTO, USPTO Assignment, Espacenet|
The named inventor of the present application has filed two is a continuation of pending U.S. patent application Ser. No. 10/974,956 filed Oct. 28, 2004, now abandoned, which is a reissue application of U.S. Pat. No. 5,805,706. U.S. Pat. No. 5,805,706 matured from application Ser. No. 08/633,581, which is a continuation-in-part of co-pending United States Patent Applications entitled (i) “Apparatus and Method for Providing Secured Communications” (application Ser. No. 08/251,486 filed May 31, 1994) now U.S. Pat. No. 5,539,828 “Secured Method for Providing Secured Communications” (application Ser. No. 08/538,869), pending and A (ii) “Method For Providing A Roving Software License In A Hardware Agent-Based System From One Node to Another Node” (application Ser. No. 08/472,951 filed Jun. 1995), now U.S. Pat. No. 5,568,522 and a recently issued patent entitled 5,568,552 which is a division of “Roving Software License For A for a Hardware Agent” (application Ser. No. 08/303,084 filed Sep. 7, 1994) now U.S. Pat. No. 5,473,692) . The present Application is also related to “Apparatus and Method for Providing Secured Communications” (application Ser. No. 08/538,869 ) now U.S. Pat. No. 5,796,840 which is a division of the 08/251,486 application. These applications and patent are owned by the same assignee of the present Application—i.e., by Intel Corp.
1. Field of the Invention
The present invention relates to the field of cryptography. More particularly, the present invention relates to a cryptographic device which translates encrypted information from one encrypted format to another without unsecured exposure of its non-encrypted format.
2. Description of Art Related to the Invention
In today's society, it is becoming more and more desirable to transmit digital information (i.e., data, control or address) from one location to another in a manner which is clear and unambiguous to a targeted recipient, but incomprehensible to any illegitimate interlopers. Accordingly, before transmission, the digital information is typically encrypted by a host processor executing an encryption algorithm stored in main memory. A communication key specific to a targeted recipient is used for such encryption. Thereafter, the targeted recipient decrypts the encrypted information for his or her own use. This conventional cryptographic transmission technique is commonly used in governmental applications as well as for commercial applications where sensitive information (e.g., confidential, proprietary, etc.) is being transmitted.
Likewise, it is further becoming desirable to store digital information in an encrypted format within main memory or a mass storage device associated with a computer. This is done to prevent an unauthorized person from downloading sensitive information in a non-encrypted format (i.e., plain text) from main memory or a mass storage device onto a floppy disk. However, neither the storage of information in an encrypted format nor the conventional cryptographic transmission technique fully protects plain text from unsecured exposure (i.e., outside the confines of the element executing the cryptographic algorithm). For example, in order to transfer an encrypted document from one computer to another, the encrypted document would be decrypted to plain text and re-encrypted with a communication key specific to the targeted recipient. Thus, the plain text will be exposed at least on the system bus and, in those cases where the document is greater in size than main memory, the plain text might be temporarily stored on the computer's mass storage device (e.g., internal hard disk). This exposure problem poses a number of disadvantages associated with security.
One clear disadvantage is that plain text may be readable by an unauthorized person in those situations where it is not immediately removed from the internal hard disk or the hard disk is accessible to other computers through a local area network. Even if the sender diligently removes the plain text from the hard disk or the document as plain text is never stored on the hard disk, there is a possibility that an interloper may gain access to the plain text by simply monitoring the system bus of the computer through software (e.g., computer-virus) or hardware means (e.g., logic analyzer).
Another disadvantage is that there is no mechanism to guarantee that only the intended recipient can read the contents of a message when the message is sent in an encrypted format to a third party (e.g., system administrator) who is responsible for re-encrypting the message with a different encrypted format.
Yet another disadvantage is that there is no mechanism to protect against unauthorized use of data provided through content distribution or by software packages (i.e., copy protection).
Hence, it would be desirable to create a cryptographic device that sufficiently mitigates access to information in a non-encrypted format (i.e., plain text) originally contained within one source in one encrypted format and needs to be transferred to another source through another or even the same encrypted format. The cryptographic device would virtually eliminate any interlopers from stealing secure information because the interloper would have to obtain that information from integrated circuits inside the chip package which is clearly more difficult than obtaining information from bus lines.
The present invention relates to a cryptographic device that decrypts information having a first encrypted format that is input into the cryptographic device producing information in a non-encrypted format. The non-encrypted information is subsequently re-encrypted according to a second encrypted format. The information having the second encrypted format is output from the cryptographic device. The decryption and re-encryption operations are accomplished entirely within the cryptographic device.
The features and advantages of the present invention will become apparent from the following detailed description of the present invention in which:
The present invention relates to an apparatus and method for translating information from one encrypted format to the same or another encrypted format without exposing the intermediary plain text to an unsecured environment. In the following description, numerous detailed are set forth in order to provide a thorough understating of the present invention. However, it is apparent to one skilled in the art that the present invention may be practiced through many different embodiments than that illustrated without deviating from the spirit and scope of the present invention. In other instances, well-known circuits, elements and the like are not set forth in detail in order to avoid unnecessarily obscuring the present invention.
In the detailed description, a number of cryptography-related terms are frequently used to describe certain characteristics or qualities which is define herein. A “communication key” is an encoding and/or decoding parameter used by cryptographic algorithms such as Rivest, Shamir and Adleman (“RSA”) which uses public and private key pairs and Data Encryption Standard (“DES”) which uses a select key shared in confidence between two parties. Normally, the communication key is a sequential distribution (“string”) of binary data being “n” bits in length, where “n” is an arbitrary number. A “document” is generally defined as information (e.g., data, address, keys, etc.) being transferred in a sequence of bus cycles. “Plain text” is defined as non-encrypted information which may include, but is not limited to digital date representing text, video audio and other mediums.
The processor subsystem 110 includes the host processor 111 which executes instructions from the memory subsystem 120 and processes information from the computer system 100. While only one host processor 111 is shown, it is contemplated that more than one processor could be employed within the computer system 100. Moreover, the memory subsystem 120 may include a memory controller 121 controlling access to one or more memory device(s) 122 such as dynamic random access memory (“DRAM”), read only memory (“ROM”), video random access memory (“VRAM”) and the like. The memory device(s) 122 store(s) information for use by the host processor 111.
The I/O subsystem 130 includes an I/O controller 131 which acts as an interface between an I/O bus 160 and the system bus 150. This provides a communication path for transferring information between devices coupled to different buses. The I/O bus 160 transfers information into and from at least one peripheral device in the computer system 100. Examples of the peripheral devices may include, but are not limited to a display device 132 (e.g., cathode ray tube, liquid crystal display, flat panel display, etc.); an alphanumeric input device 133 (e.g., keyboard, key pad, etc.); a cursor control device 134 (e.g., a mouse, trackball, touchpad, joystick, etc.); a mass data storage device 135 (e.g., magnetic tapes, hard disk drive, floppy disk drive, etc.); an information transceiver device 136 (fax machine, modem, scanner etc.) allowing information to be transferring from the computer system 100 to a remotely located system and vice versa; and a hard copy device 137 (e.g., plotter, printer, etc.). It is contemplated that the computer system 100 shown in
Besides a computer system, it is further contemplated that the cryptographic device 140 may be implemented in any electronic system that relies on encrypted communications. For example, these electronic systems may include cable television control boxes, bank ATM machines and perhaps networked peripheral nodes that could be configured to receive information in one encrypted format and transmit or store the information in another encrypted format. These examples are illustrative and should not be construed as a limitation to the present invention.
Referring now to
The decryption unit 143 receives information in a first encrypted format (“encrypted data in”) and decrypts that information. Thus, the decryption unit 143 is configured with the necessary communication key “KEYin” to decrypt the information thereby producing the information as plain text. Thereafter, the decryption unit 143 may be hardware or firmware implemented to function accordingly. The encryption unit 144 receives the plain text and re-encrypts it according to a selected communication key “KEYout” to produce re-encrypted information (“encrypted data out”). The encrypted information is output from the cryptographic device 140 to the memory subsystem or mass storage device for storage or to the transceiver unit for transmission to another remotely located system.
The decryption unit 143 and encryption unit 144 may be hardware or firmware implemented to function as described above. Clearly, the decryption unit 143 and encryption unit 144 may be a general purpose microprocessor with cryptographic algorithms executed and plain text maintained within a secure environment or any intelligent electronic device capable of performing this decryption or encryption.
It is contemplated that other implementations may be used. For example, in
In the event that the encrypted information propagates into the first cryptographic unit 240, the first cryptographic unit 240 decrypts the encrypted information into a plain text format and transfers the decrypted information via communication line(s) 241 into the memory unit 230. Alteratively, in the event that the encrypted information propagates into the processor 200, the processor 200 executes a particular cryptographic algorithm to decrypt the encrypted information and transmits the decrypted information in its plain text form into the memory unit 230 via communication line(s) 203.
In order to encrypt the plain text into a second encrypted format, three alternative data paths could be followed. A first data path is where the plain text is to be encrypted with the same format upon which the information was received. In this case, the plain text propagates through communication line(s) 242 into the first cryptographic unit 240 which, this time, encrypts the plain text into the first encrypted format and outputs that information into an output buffer 220 via communication line(s) 221. The second data path is where the plain text needs to be encrypted with an encrypted format not provided by either the first or second cryptographic units 240 and 250. In this situation, the plain text is transferred to the processor 200 via communication line(s) 204. The processor 200 receives the plain text and encrypts that information upon executing an associated cryptographic algorithm. Thereafter, the processor 200 transfers the encrypted information to the output buffer 220 via communication line(s) 222. A third alternative data path is where the plain text is to be encrypted with a format provided by a second cryptographic unit 250. The plain text is provided to the second cryptographic unit 250 via communication line(s) 251. The second cryptographic unit 250 encrypts the plain text into the second encrypted format and transmits that information to the output buffer 220 via communication line(s) 223. Thereafter, the output buffer 220 transfers the encrypted information to the system bus for storage in the memory device or mass storage device or for transmission to a remote system via the information transceiver device.
It is contemplated that copy protection may be provided by merely encrypting at least a portion of the context distributed data and that data being decrypted, processed and later encrypted for storage within the cryptographic device.
Referring now to
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|U.S. Classification||713/189, 380/28, 713/172, 713/153|
|International Classification||H04L9/14, H04L9/00|
|European Classification||H04L9/00, H04L9/08|