Tools that correctly read ZIP archives must scan for the signatures of the various fields, in the ZIP central directory. ZIP tools are required by the specification to ignore Extra fields they do not recognize. Other extensions are possible via the “Extra” field. “Extra” fields are exploited to support the ZIP-64 format, WinZip-compatible AES encryption, file attributes, and higher-resolution NTFS or Unix file timestamps. The “Extra” data fields are the key to the extensibility of the ZIP format.

Each entry is introduced by a local header with information about the file such as the comment, file size, and file name, followed by optional “Extra” data fields, and then the possibly compressed, possibly encrypted file data. The order of the file entries in the directory need not coincide with the order of file entries in the archive. The entries in the ZIP file also include this information for redundancy. This allows a file listing of the archive to be performed relatively quickly, as the entire archive does not have to be read to see the list of files. The central directory stores a list of the names of the entries (files or directories) stored in the ZIP file, along with other Metadata about the entry, and an offset into the ZIP file, pointing to the actual entry data. You can see below, what a ZIP file looks like and it will give you a clear picture of the ZIP file structure Meaning of Zip File in Simple WordsĪ ZIP file is identified by the presence of a central directory which is located at the end of the structure in order to allow the appending of new files. Structure of a ZIP File and How does it Work How to Compress & Uncompress a Zip Files.

Structure of a ZIP File and How does it Work.

How to convert a file into a zip file