Enabling random access within objects in ZIP archives

Objects stored in a zip archive may be extracted in random-access fashion (without involving other objects stored in the zip archive) using the addresses of the objects stored in the central directory of the zip archive. However, zip archives often provide insufficient information to enable random access to the data within an object. This capability may be provided by segmenting the object into sections of a section size, and including in the zip archive a block table specifying, for respective sections, the block size of the corresponding block. A zip archive extractor may achieve random access to the object by using the block table to computing the addresses of blocks comprising the selected portion and extracting only those blocks. Backwards compatibility of the zip archive with other zip archive extractors may be preserved by including the block table within a zip extension of the central directory of the zip archive.