PoC for JDK-4347142: Need method to set Password protection to Zip entries

[KUBOTA Yuji]

Hi all,

Our customers have to handle password-protected zip files. However,
Java SE does not provide the APIs to handle it yet, so we must use
third party library so far.

Recently, we found JDK-4347142: "Need method to set Password
protection to Zip entries", and we tried to implement it.

The current zlib in JDK is completely unaffected by this proposal. The
traditional zip encryption encrypts a data after it is has been
compressed by zlib.[1] So we do NOT need to change existing zlib
implementation.

We've created PoC and uploaded it as webrev:

    http://cr.openjdk.java.net/~ysuenaga/JDK-4347142/webrev.00/

    Test code is as below. This code will let you know how this PoC works.
    http://cr.openjdk.java.net/~ysuenaga/JDK-4347142/webrev.00/Test.java

In NTT, a Japanese telecommunications company, we are providing many
enterprise systems to customers. Some of them, we need to implement to
handle password-protected zip file. I guess that this proposal is
desired for many developers and users.

I'm working together with Yasumasa Suenaga, jdk9 committer (ysuenaga).
We want to implement it if this proposal accepted.

[1]: https://pkware.cachefly.net/webdocs/APPNOTE/APPNOTE-6.3.3.TXT
(6.0  Traditional PKWARE Encryption)


Thanks,
Yuji