| 摘要 |
A system and method are disclosed for rendering published documents tamper evident. Embodiments render classes of documents tamper evident with cryptographic level security or detect tampering, where such security was previously unavailable, for example, documents printed using common printers without special paper or ink. Embodiments enable proving the date of document content without the need for expensive third party archival, including documents held, since their creation, entirely in secrecy or in untrustworthy environments, such as on easily-altered, publicly-accessible internet sites. Embodiments can extend, by many years, the useful life of currently-trusted integrity verification algorithms, such as hash functions, even when applied to binary executable files. Embodiments can efficiently identify whether multiple document versions are substantially similar, even if they are not identical, thus potentially reducing storage space requirements. |
| 主权项 |
1. A computer-implemented document integrity verification method, executable by a processor, the method comprising:
receiving a digital document in a word processing format into a non-transitory computer readable medium; generating a first baseline data sequence from the digital document, the first baseline data sequence having a first printable element and a second printable element following the first printable element of the first baseline data sequence; generating a first modified data sequence from the first baseline data sequence in accordance with a set of modification rules, the first modified data sequence having a first printable element and a second printable element following the first printable element of the first modified data sequence,
wherein the first printable element of the first modified data sequence is identical to the first printable element of the first baseline data sequence,wherein the second printable element of the first modified data sequence is identical to the second element of the first baseline data sequence,wherein at least one unprintable element of the first baseline data sequence, between the first and final printable elements of the first baseline data sequence, is not in the first modified data sequence, so that the first modified data sequence is shorter than the first baseline data sequence,and wherein an integrity verification code (IVC) generated for the first modified data sequence will differ from an IVC generated for the first baseline data sequence; generating a first original IVC, wherein generating a first original IVC comprises performing a one-way operation on the first modified data sequence, and wherein the modification rules render tampering of the digital document undetectable for the at least one unprintable element within the first baseline data sequence; generating a second baseline data sequence from the digital document, the second baseline data sequence having a first printable element and a second printable element following the first printable element of the second baseline data sequence;
wherein the second baseline data sequence is different than the first baseline data sequence, generating a second modified data sequence from the second baseline data sequence in accordance with the set of modification rules, the second modified data sequence having a first printable element and a second printable element following the first printable element of the second modified data sequence,
wherein the first printable element of the second modified data sequence is identical to the first printable element of the second baseline data sequence,wherein the second printable element of the second modified data sequence is identical to the second element of the second baseline data sequence,wherein at least one unprintable element of the second baseline data sequence, between the first and final printable elements of the second baseline data sequence, is not in the second modified data sequence, so that the second modified data sequence is shorter than the second baseline data sequence,and wherein an IVC generated for the second modified data sequence will differ from an IVC generated for the second baseline data sequence; generating a second original IVC, wherein generating a second original IVC comprises performing a one-way operation on the second modified data sequence, and wherein the modification rules render tampering of the digital document undetectable for the at least one unprintable element within the second baseline data sequence; and publishing the digital document with at least a portion of the first original IVC and the second original IVC rendered on a face of the published document. |
