Yuji,
I'm not convinced that the ZipCryption is a public interface we'd like to
expose,
at least for now, given the proprietary nature of the "strong encryption"
defined
by PKWARE.
As I said in my previous email, it might be desired to hide the
"passwd/encryption"
support for the "traditional zip encryption" as an implementation detail.
Looking at the existing methods that deal with "entry" in ZipFile,
ZipInputStream
and ZipOutputStream,
ZipFile.getInputStream(ZipEntry e);
ZipOutputStream.putNextEntry(ZipEntry e);
ZipInputStream.getNextEntry();
it appears that instead of adding "password" specific method to these classes
directly, it might be more appropriate to extend the ZipEntry class for such
"password" functionality. For example, with a pair of new methods
boolean ZipEntry.isTraditionalEncryption().
void ZipEntry.setTraditionalEncryption(String password);
The encryption support should/can be added naturally/smoothly with
ZipFile.getInputStream(e), ZipInputstream and ZipOutputStream.putNextEntry(e),
with no extra new method in these two classes. The implementation checks
the flag (bit0, no bit 6) first and then verifies the password, as an
implementation
details.
For ZipFile and ZipInputStream, we can add note to the api doc to force the
invoker to check if the returned ZipEntry indicates it's an encrypted entry. If
yes,
it must to set the appropriate password to the returned ZipEntry via
ZipEntry.setTraditionalEncryption(password); before reading any byte from the
input stream.
Again, we should not have any "encryption" related public field/method in
DeflaterOutputStream/InflaterInputStream. Ideally these two classes really
should
not be aware of "encryption" at all.
-Sherman
On 01/04/2016 06:26 AM, KUBOTA Yuji wrote:
Hi Sherman and all,
Happy new year to everyone!
Please let know your feedback about this proposal. :-)
Thanks,
Yuji
2015-12-21 22:38 GMT+09:00 KUBOTA Yuji<[email protected]>:
Hi Sherman,
2015-12-20 16:35 GMT+09:00 Xueming Shen<[email protected]>:
It is no longer necessary to touch the native code (zip_util.c/h) after the
native ZipFile implementation has been moved up to the java level. Those
native code are for vm access only now, which I dont think care about the
password support at all.
Thanks for your information. We do not take care the native.
I discussed with Yasumasa, and our thought is as below.
(1) what's the benefit of exposing the public interface ZipCryption? the real
question is whether or not this interface is good enough for other encryption
implementation to plugin their implementation to support the ZipFile/Input/
OutputStream to their encryption spec.
We aimed that the public interface ZipCryption supports the
extensibillity for other encrypt engine. The JDK core libs developers
have to implementation ZipyCryption only. If not provide, the JDK
developers must implement ZipStream/Entry by JDK API to design the
data structure of entry.
If you want to use binary key data such as PKI, you can implement new
encrypt/decrypt engine by ZipCryption interface.
So we think we should provide this interface to be clearly how to
implement a new engine, e.g., cipher algorithm, cipher strength and
converting the header, etc.
(2) it seems like it might be possible to hide most of the implementation
and only expose the "String password" (instead of the ZipCryption) as the
public interface to support the "traditional" encryption. This depends on the
result of (1) though.
Thanks for your clues. We think the string password at first. However,
we should also create a new binary interface given we support PKI in
the future.
(3) I'm concerned of pushing ZipCryption into
InflaterInputStream/DeflaterOutputStream.
It might be worth considering to replace the ZipCryption implementation with
a pair of FilterOutput/InputStream. It would be easy and reasonable to use
the FilterOutputStream for the ZipOutputStream and the FilterInputStream for the
ZipFile. The PushbackInputStream in ZipInputStream might be an issue ...
Thanks for your clues, too. Honestly speaking, we think the current
zip implementation may break the data when used PushbackInputStream
for the following reasons.
* PushbackInputStream uses an unique internal buffer for re-read operation.
* But, InflaterInputStream provide date to Inflater per reads and
buffer by JNI (zlib).
* So we think PushbackInputStream is poor compatibility with
InflaterInputStream.
We generally use InputStream through ZipEntry#getInputStream(). We do
not touch FileInputStream for reading ZIP data. If we call unread()
when we use PushbackInputStream as reading ZIP archive, we guess that
it will break the reading data.
So, our approach do not affect the PushbackInputStream.
What do you think about this?
(4) It seems the ZipOutputStream only supports the "stream based" password,
while
the ZipInputStream supports the "entry based" password. Do we really need
"entry based" support here?
As your suggestion, we should support "entry based". We will start to
implement "entry based" after this discussion is closed.
Thanks,
Yuji
On 12/17/15, 9:45 PM, Yasumasa Suenaga wrote:
Hi Jason,
Thank you for your comment.
I've fixed it in new webrev:
http://cr.openjdk.java.net/~ysuenaga/JDK-4347142/webrev.03/
Thanks,
Yasumasa
On 2015/12/17 0:33, Jason Mehrens wrote:
The null check of 'entry' at line 351 of ZipFile.getInputStream is in
conflict with line 350 and 348.
________________________________________
From: core-libs-dev<[email protected]> on behalf of
Yasumasa Suenaga<[email protected]>
Sent: Wednesday, December 16, 2015 8:47 AM
To: Sergey Bylokhov; Xueming Shen
Cc: [email protected]
Subject: Re: [PING] PoC for JDK-4347142: Need method to set Password
protection to Zip entries
Hi Sergey,
Thank you for your comment.
I added that description in new webrev:
http://cr.openjdk.java.net/~ysuenaga/JDK-4347142/webrev.02/
Thanks,
Yasumasa
On 2015/12/16 22:19, Sergey Bylokhov wrote:
Should the new methods describe how they will work in case of null
params?
On 16/12/15 16:04, Yasumasa Suenaga wrote:
I adapted this enhancement after JDK-8145260:
http://cr.openjdk.java.net/~ysuenaga/JDK-4347142/webrev.01/
Could you review it?
Thanks,
Yasumasa
On 2015/12/12 21:23, Yasumasa Suenaga wrote:
Hi Sherman,
Our proposal is affected by JDK-8142508.
We have to change ZipFile.java and and ZipFile.c .
Thus we will create a new webrev for current (after 8142508) jdk9/dev
repos.
Do you have any comments about current webrev?
http://cr.openjdk.java.net/~ysuenaga/JDK-4347142/webrev.00/
If you have comments, we will fix them in new webrev.
Thanks,
Yasumasa
On 2015/12/03 16:51, KUBOTA Yuji wrote:
Hi Sherman,
Thanks for your quick response :)
I aimed to implement the "traditional" at this proposal by the below
reasons.
* We want to prepare API for encrypted zip files at first.
* Many people use the "traditional" in problem-free scope like a
temporary file.
* We do not know which implementation of the "stronger" is best
for
openjdk.
* PKWare claims that they have patents about the "stronger" on
Zip[1].
* OTOH, WinZip have the alternative implementation of the
"stronger" [2][3].
* Instead, we prepared the extensibility by ZipCryption interface
to
implement other encrypt engine, such as the AES based.
Thus, I think this PoC should support the "traditional" only.
In the future, anyone who want to implement the "stronger" can easily
add their code by virtue of this proposal.
[1] https://pkware.cachefly.net/webdocs/APPNOTE/APPNOTE-6.3.3.TXT
(1.4 Permitted Use& 7.0 Strong Encryption Specification)
[2]
https://en.wikipedia.org/wiki/Zip_(file_format)#Strong_encryption_controversy
[3] http://www.winzip.com/aes_info.htm
Thanks,
Yuji
2015-12-03 12:29 GMT+09:00 Xueming Shen<[email protected]>:
Hi Yuji,
I will take a look at your PoC. Might need some time and even bring
in the
security guy
to evaluate the proposal. It seems like you are only interested in
the
"traditional PKWare
decryption", which is, based on the wiki, "known to be seriously
flawed, and
in particular
is vulnerable to known-plaintext attacks":-) Any request to support
"stronger" encryption
mechanism, such as the AES based?
Regards,
Sherman
On 12/2/15 6:48 PM, KUBOTA Yuji wrote:
Hi all,
We need reviewer(s) for this PoC.
Could you please review this proposal and PoC ?
Thanks,
Yuji
2015-11-26 13:22 GMT+09:00 KUBOTA Yuji<[email protected]>:
Hi all,
* Sorry for my mistake. I re-post this mail because I sent before
get
a response of subscription confirmation of core-libs-dev.
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
