Complex document security
First Claim
1. A method of handling a document for transmission external of a secure computer environment, comprising the steps of:
- (a) applying a document to at least one filter to eliminate or corrupt the content or form of covert information contained within said document;
(b) displaying to a viewer said filtered document or a predetermined portion thereof in a trusted manner; and
(c) communicating said filtered document in a secure manner, external of said secure computer environment, if said filtered and displayed document appears to be acceptable to said viewer.
1 Assignment
0 Petitions
Accused Products
Abstract
A method and means to control the degree to which the presence of covert information may be reduced, eliminated or corrupted in documents created on a computer device (particularly complex documents) before the document is transmitted outside a secure environment in which the document is created. The process of handling a document in a secure environment comprises the preferred step of displaying the document or a predetermined portion thereof in a manner which conforms to the rule that no pixel of the display is written to more than once for the current portion of the document being displayed. Preferably the method includes the steps of creating a document, transforming the document into an intermediate form by defining the content and structure of the document using a predetermined set of document describers, applying the intermediate form of the document to at least one filter adapted to eliminate or corrupt the content and form of any covert information contained within the intermediate form of the document followed by the previously described step of displaying the document in the manner described above.
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Citations
31 Claims
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1. A method of handling a document for transmission external of a secure computer environment, comprising the steps of:
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(a) applying a document to at least one filter to eliminate or corrupt the content or form of covert information contained within said document; (b) displaying to a viewer said filtered document or a predetermined portion thereof in a trusted manner; and (c) communicating said filtered document in a secure manner, external of said secure computer environment, if said filtered and displayed document appears to be acceptable to said viewer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 16, 17)
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13. A method of handling a document for transmission external of a secure computer environment, comprising the steps of:
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(a) applying a document to at least one filter to eliminate or corrupt the content or form of covert information contained with said document; (b) displaying to a viewer said filtered document or a predetermined portion thereof in a trusted manner; (c) communicating said filtered document, in a secure manner, if said filtered and displayed document appears acceptable to said viewer, by associating with said filtered document a seal which indicates that said document can be communicated external of said secure computer environment; (d) receiving with a trusted gateway device located within said secure computer environment said document with its associated seal; (e) checking the validity of said seal with a trusted verification means, and if and only if said seal is validly associated with said document; and (f) communicating said document external of said secure computer environment. - View Dependent Claims (14, 15)
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18. A method of handling a document for transmission external of a secure computer environment, comprising the steps of:
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(a) applying a document to at least one filter to eliminate or corrupt the content or form of covert information contained within said document, wherein if not already a digital image, at least one of said filters converts said document or a portion thereof into a first digital image; (b) converting said document or said first digital image into an analog form; (c) converting said analog form into a second digital image, which comprises the filtered document or a portion thereof; (d) displaying to a viewer said filtered document or a predetermined portion thereof in a trusted manner; and (e) communicating said filtered document in a secure manner, external of said secure computer environment, if said filtered and displayed document appears to be acceptable to said viewer. - View Dependent Claims (19, 20, 21)
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22. A method of handling a document for transmission external of a secure computer environment, comprising the steps of:
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(a) applying a document to at least one filter to eliminate or corrupt the content or form of covert information contained within said document, wherein if not already a digital image, at least one of said filters converts said document or a portion thereof into a first digital image; (b) converting said document or said first digital image into a second digital image such that one or more pixel values from said first digital image is combined with itself or a predetermined value to produce one or more pixel values in said second digital image wherein said second digital image comprises said filtered document or a portion thereof; (c) displaying to a viewer said filtered document or a predetermined portion thereof in a trusted manner; and (d) communicating said filtered document in a secure manner, external of said secure computer environment, if said filtered and displayed document appears to be acceptable to said viewer. - View Dependent Claims (23, 24, 25, 26, 27, 31)
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28. A method of a handling a document for transmission external of a secure computer environment, comprising the steps of:
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(a) displaying said document or a predetermined portion thereof in a trusted manner; (b) applying said document or a predetermined portion thereof to at least one filter to eliminate or corrupt the content or form of covert information contained within said document or portion thereof wherein at least one of said filters is trusted; and (c) communicating said filtered and displayed document in a secure manner external of said secure computer environment, if said displayed document appears acceptable to the viewer of the document. - View Dependent Claims (29, 30)
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Specification