1

A document integrity verification method comprising:receiving an image format document representing a printed document, wherein the image format document represents a printed document containing a first original integrity verification code (IVC);

generating a first verification data sequence from the image format document, wherein generating a first verification data sequence comprises performing an optical character recognition (OCR) process on the image format document;

generating a first modified verification data sequence from the first verification data sequence in accordance with a set of modification rules, wherein at least one element of the first verification data sequence, between the first and final elements of the first verification data sequence, is modified in the first modified verification data sequence;

generating a first verification IVC, wherein generating a first verification IVC comprises performing a one-way operation on the first modified verification data sequence;

comparing the first verification IVC with the first original IVC; and

reporting an indication of tampering to the printed document, responsive to the comparison of the first verification IVC with the first original IVC.

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2

The method of Claim 1 wherein the image format document comprises a portable document format (PDF) document.

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3

The method of Claim 1 wherein the image format document comprises an image of the first original IVC.

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4

The method of Claim 3 wherein generating a first verification data sequence further comprises:identifying the image of the first original IVC in the image format document; and

excluding the first original IVC from the first modified verification data sequence.

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5

The method of Claim 3 wherein a separate OCR process is performed on a portion of the image format document containing the image of the first original IVC.

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6

The method of Claim 1 wherein the first modified verification data sequence is shorter than the first verification data sequence.

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7

The method of Claim 1 wherein modifying an element of the first modified verification data sequence comprises omitting the element from the first modified verification data sequence.

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8

The method of Claim 1 wherein modifying an element of the first modified verification data sequence comprises substituting the element with a different element in the first modified verification data sequence.

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9

The method of Claim 1 wherein the modification rules require modification of at least one element which does not correspond to a printed element in the printed document.

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10

The method of Claim 1 wherein the modification rules require that at least one element, which does correspond to a printed element in the printed document, appear in the first modified verification data sequence without modification.

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