Recommendations on a free library to be used for zipping files [closed]

Question

I need to zip and password-protect a file. Is there a good (free) library for this?

This needs to be opened by a third party, so the password protection needs to work with standard tools.

Answer 1

You can try Zip4j, a pure java library to handle zip file. It supports encryption/ decryption of PKWare and AES encryption methods.

Key features:

• Create, Add, Extract, Update, Remove files from a Zip file
• Read/Write password protected Zip files
• Supports AES 128/256 Encryption
• Supports Standard Zip Encryption
• Supports Zip64 format
• Supports Store (No Compression) and Deflate compression method
• Create or extract files from Split Zip files (Ex: z01, z02,...zip)
• Supports Unicode file names
• Progress Monitor

License:

• Zip4j is released under Apache License, Version 2.0.

Answer 2

UPDATE 2020: There are other choices now, notably Zip4J.

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After much searching, I've found three approaches:

A freely available set of source code, suitable for a single file zip. However, there is no license. Usage is AesZipOutputStream.zipAndEcrypt(...). http://merkert.de/de/info/zipaes/src.zip (https://forums.oracle.com/forums/thread.jspa?threadID=1526137)

UPDATE: This code is now Apache licensed and released at https://github.com/mobsandgeeks/winzipaes (exported from original home at Google code) . It worked for me (one file in the zip), and fills a hole in Java's opens source libraries nicely.

A commercial product ($500 at the time of writing). I can't verify if this works, as their trial license approach is complex. Its also a ported .NET app: http://www.nsoftware.com/ipworks/zip/default.aspx

A commercial product ($290 at the time of writing). Suitable only for Wnidows as it uses a dll: http://www.example-code.com/java/zip.asp