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METHODS, SYSTEMS AND COMPUTER
PROGRAM PRODUCTS FOR MULTI-LEVEL
ENCRYPTION
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FIELD OF THE INVENTION
The present invention relates to cryptography and more particularly to the encryption where multiple access rights are provided.
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BACKGROUND OF THE INVENTION
With electronic documents, security is often a concern. One conventional way to protect a document is by associating a password or a key with the document and then encrypting the document content with the password or key. 15 Thus, only users with the password or key may decrypt the document contents to view the contents.
However, the conventional encryption of a document typically only provides for a single level of protection. Thus, for example, if portions of a document are only to be viewed 20 by certain authorized users and other portions are to be accessible by a different user or group of users, then it may be necessary, with conventional encryption techniques, to create multiple versions of the document. Each version would then be encrypted with different keys or passwords. Such an approach may be inefficient, time consuming and may, in some cases, compromise security as multiple versions of a secure document may make location and access of the document by an unauthorized party more likely. ^
One approach to providing different levels of security for a document is described in commonly assigned U.S. patent application Ser. No. 09/240,387 to Fletcher et al, entitled "METHOD, SYSTEM AND APPARATUS FOR SELECTING ENCRYPTION LEVELS BASED ON POLICY 3J PROFILING," the disclosure of which is incorporated herein as if set forth in its entirety. In Fletcher et al. documents are stored in an unencrypted database and different parts of a document are annotated with different security levels. When a request for the document is received 4Q a server looks up the requestor and determines which level(s) of information the requester is permitted to access. The server then inspects the document and niters out the content that the requestor is not allowed to access. The content which is not filtered out is then encrypted and 4J provided to the user.
While the approach of Fletcher et al. provides differentiated levels of security for a document without requiring the storage of multiple versions of the document, this approach may be processor intensive as it utilizes a centralized 50 resource to control the dissemination of information in documents. Furthermore, such an approach may be limiting in the event that a document is to be widely distributed, as distribution would involve subsequent interaction with the server to obtain the appropriate version of the document for 55 each recipient in the distribution list.
In light of the above discussion, a need exists for improvements in the encryption of documents which allows for different levels of access to the documents.
SUMMARY OF THE INVENTION 60
In view of the above discussion, it is an object of the present invention to provide different levels of access to a document.
A further object of the present invention is to provide 65 different levels of access to a document utilizing information contained in the document itself.
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Still another object of the present invention is to provide multiple levels of access to a document which may be provided at the time of document generation or upon document access.
These and other objects of the present invention may be provided by methods, systems, and computer program products which encrypt a document by dividing the document into at least a first portion having a first security level and a second portion having a second security level. The document is then encrypted utilizing at least two encryption keys so as to encrypt the first portion of the document with a first of the at least two encryption keys and so as to encrypt the second portion of the document with a second of the at least two encryption keys. Although each portion of the document may be separately encrypted, preferably, the document is sequentially encrypted utilizing at least two encryption keys so as to encrypt the first portion of the document with a first of the at least two encryption keys and so as to encrypt the first and the second portion of the document with a second of the at least two encryption keys.
By separately encrypting portions of a document, the document may be later selectively decrypted to provide different levels of access to the document. Furthermore, by sequentially encrypting a document with separate encryption keys, the document may be decrypted to provide differing levels of access to the document without separately providing information about which portions of the document are encrypted with which encryption keys. Also, because the encryption process is independent of when the document is created, the encryption may be performed at the time of generation of the document or at a later time.
In a further embodiment of the present invention, a set of encryption keys corresponding to the portions of the document to be decrypted by an intended recipient of the document is incorporated into the document. The incorporated set of encryption keys may be encrypted utilizing an encryption key associated with the intended recipient to provide further security. Also, a plurality of sets of encryption keys may be incorporated for different intended recipients. By incorporating the encryption keys into the document, the document may be selectively decrypted without requiring further information about the document. Furthermore, the intended recipients and their respective levels of access may be controlled by controlling the sets of encryption keys that are incorporated into the document. Thus, the document may provide a self-contained mechanism for providing controlled access to the contents of the document.
In a still further embodiment of the present invention, the first portion of the document is decrypted utilizing the first encryption key and the second portion of the document is decrypted utilizing the second encryption key. Preferably, the first and the second portions of the document are decrypted utilizing the second encryption key and the first portion of the document is decrypted utilizing the first encryption key. If the encryption keys are incorporated into the document as a set of encryption keys, then the document may be decrypted utilizing the set of encryption keys incorporated into the document. Furthermore, the set of encryption keys may be decrypted utilizing the encryption key associated with the intended recipient after which the document may be decrypted utilizing the decrypted encryption keys contained within the set of encryption keys.
If a document is sequentially encrypted utilizing encryption keys contained within the set of encryption keys, then the document may be decrypted by sequentially decrypting the document utilizing the decrypted encryption keys in the
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set of encryption keys. The sequential decryption may be provided in a sequential order in reverse to the sequential order in which the document was encrypted.
In a still further embodiment of the present invention, an encrypted document is provided having a first portion of the document encrypted with a first encryption key and a second portion of the document, different from the first portion, encrypted with both the first encryption key and a second encryption key. The document may also include a third portion of the document which is unencrypted. The document may further include a key area containing at least one of the first encryption key and the second encryption key. If such is the case, then, preferably, the key area is encrypted with a third encryption key. The encrypted document may be a video clip, a word processing document, an audio clip, a spreadsheet, a database and/or a multimedia presentation.
As will further be appreciated by those of skill in the art, the present invention may be embodied as methods, apparatus/systems and/or computer program products.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is diagram of a data processing system incorporating an embodiment of the present invention;
FIG. 2 is a detailed view of a data processing system incorporating an embodiment of the present invention;
FIG. 3 is an illustration of a document encrypted according to an embodiment of the present invention;
FIG. 4 is a flowchart illustrating operations according to one embodiment of the present invention;
FIG. 5 is a flowchart illustrating operations according to a further aspect of the present invention; and
FIG. 6 is a flowchart illustrating operations according to a still further aspect of the present invention.
DETAILED DESCRIPTION OF THE
INVENTION
The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout.
The present invention can be embodied as systems, methods, or computer program products for multiple level encryption and/or decryption of documents. As used herein, the term "document" includes a computer file or other stored information which may be partitioned and encrypted. Thus, while the present invention is described with reference to a text document, as will be appreciated by those of skill in the art, other documents may be encrypted or decrypted utilizing the teachings of the present invention. Thus, for example, a video or audio clip may be a document according to the present invention as well as a presentation, graphic, image or other such information sources which may be partitioned into portions associated with a particular security level or access group.
As will be further appreciated by those of skill in the art, the present invention can take the form of an entirely hardware embodiment, an entirely software (including firmware, resident software, micro-code, etc.) embodiment, or an embodiment containing both software and hardware
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aspects. Furthermore, the present invention can take the form of a computer program product on a computer-usable or computer-readable storage medium having computerusable or computer-readable program code means embodied
5 in the medium for use by or in connection with an instruction execution system. In the context of this document, a computer-usable or computer-readable medium can be any means that can contain, store, communicate, propagate, or transport the program for use by or in connection with the instruction execution system, apparatus, or device.
The computer-usable or computer-readable medium can be, for example, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, device, or propagation medium. More
15 specific examples (a nonexhaustive list) of the computerreadable medium would include the following: an electrical connection having one or more wires, a removable computer diskette, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only
20 memory (EPROM or Flash memory), an optical fiber, and a portable compact disc read-only memory (CD-ROM). Note that the computer-usable or computer-readable medium could even be paper or another suitable medium upon which the program is printed, as the program can be electronically
25 captured, via, for instance, optical scanning of the paper or other medium, then compiled, interpreted, or otherwise processed in a suitable manner if necessary, and then stored in a computer memory.
Referring now to FIG. 1, an exemplary embodiment of a
30 computer system 30 in accordance with the present invention typically includes input devices 32, such as a keyboard or keypad 31 and/or a microphone 42. The computer system 30 also preferably includes a display 34 and a memory 36 that communicate with a processor 38. The computer system
35 30 may further include a speaker 44 and an I/O data port(s) 46 that also communicate with the processor 38. The I/O data ports 46 can be used to transfer information between the computer system 30 and another computer system or a network (e.g., the Internet). FIG. 1 also illustrates that
40 computer system 30 may include a storage device 40 which communicates with memory 36 and processor 38. Such a storage device may be any type of data storage device as described above.
Furthermore, while the present invention is described
45 with respect to the computer system 30, as will be appreciated by those of skill in the art, the present invention may be incorporated into other types of devices where document encryption/decryption may be performed. For example, the present invention may comprise an embedded function in
50 many other devices. Thus, the present invention should not be construed as limited to use in computer systems such as illustrated in FIG. 1 but may be incorporated in any device having sufficient processing capabilities to carry out the operations described below.
55 FIG. 2 is a more detailed block diagram of the computer system 30 that illustrates one application of the teachings of the present invention. The processor 38 communicates with the memory 36 via an address/data bus 48. The processor 38 can be any commercially available or custom microproces
60 sor or other processing system capable of carrying out the operations of the present invention. The memory 36 is representative of the overall hierarchy of memory devices containing the software and data used to implement the functionality of the computer system 30. The memory 36
65 can include, but is not limited to, the following types of devices: cache, ROM, PROM, EPROM, EEPROM, flash, SRAM, and DRAM.
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