System and method for ISO image update and ISO image deconstruction into modular components
AssigneeLenovo (Singapore) Pte. Ltd.
InventorsRod David Waltermann, Mark Charles Davis, Seiichi Kawano
Life of this patent
Estimating the term…
Abstract
A method for updating an ISO file, e.g., to add a digital signature to the ISO file, includes adding a supplemental file composed of, e.g., all zeroes to the ISO file before recording, and then recording the ISO file with supplemental file to an optical disk using ISO format. A digital signature is computed after recording. The zeroes in the supplemental file are replaced by the values of the digital signature and the file is re-saved. Also, an ISO file that might have a common part and several unique parts, e.g., for respective languages, is deconstructed such that only a single copy of the common part is recorded to disk, avoiding multiple recordations of the same data.
Claims6
A method for adding a digital signature to an ISO file, comprising:
- adding a supplemental data structure composed of substantially all place holder values to the ISO file before recording the ISO file to an optical disk;
- saving the ISO file with supplemental data structure, a table of contents (TOC) being associated with the ISO file and including information related to a location of the supplemental data structure;
- computing a digital signature for the ISO file with supplemental data structure after saving;
- using the TOC to locate the supplemental data structure;
- replacing at least some place holder values in the supplemental data structure with values of the digital signature to render a signed ISO file;
- and
- recording the signed ISO file to the optical disk.
A reading computer for reading at least one ISO file from an optical disk, the ISO file having a digital signature recorded with it on the disk, comprising:
- logic reading the digital signature from the disk;
- logic maintaining a copy of the digital signature in a memory of the reading computer;
- logic reading the ISO file from the disk;
- logic computing a test signature from the ISO file;
- logic comparing the test signature with the digital signature to determine whether the signatures match;
- logic maintaining an offset of the digital signature in memory and logic reading the ISO file to the offset;
- and
- logic replacing the values of the digital signature with place holder values and computing the test signature based on the file read to the offset and the digital signature with place holder values.
Dependencies are inferred from the claim text.