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NetEase NPK (EXPK) Archive Decryptor

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Bigchillghost
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NetEase NPK (EXPK) Archive Decryptor

Post by Bigchillghost » Sun Jul 07, 2019 4:05 pm

- Feature:
Decrypt encrypted NPK archives with "EXPK" signature and write the data back into the source archive.

- Usage:
The tool requires an encryption key in order to perform the decryption. You can get the up-to-date key from here. Copy all the files (including the key) into your working directory and run the batch file.

- Supported Games:
Marvel Super War
Onmyoji Arena

- Note:
The key provided above is compatible for both Onmyoji Arena (OA) and Marvel Super War (MSW) below v2.6.0. MSW above v2.6.0 has switched to a different key which can be downloaded here.

- About Encryption Key:
The two games above use simple xor for encryption, but with an infinite fixed sequence as key. Now thanks to BlueEffie the method to compute the key is made public. But for the sake of the continuity of this tool and its performance, I decided to not change the old routine but simply update the xorkey for both games.

Below is the historic info of the xor key just for record:
1. The original key (871 KB) mostly was taken from this page (credit to zhouhang95).
2. The previous key described in this post has been extended by 980% in length (9414 KB) compared with the original one, making it possible to decrypt larger data. It's sufficient to handle the largest asset of OA and MSW (up to v2.6.0).
3. Current xor keys for both games are extended to 16 mega bytes using the method posted by BlueEffie.

EXPKDec.zip
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Last edited by Bigchillghost on Fri Feb 21, 2020 7:59 am, edited 10 times in total.
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Re: NetEase NPK (EXPK) Archive Decryptor

Post by TakeAaron » Sun Jul 07, 2019 4:42 pm

thank you
Last edited by TakeAaron on Thu Jul 11, 2019 6:49 am, edited 1 time in total.

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Re: NetEase NPK (EXPK) Archive Decryptor

Post by huitbgoiouythy » Mon Jul 08, 2019 9:32 am

Thank you! Gonna test this out for Marvel Super War.

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Re: NetEase NPK (EXPK) Archive Decryptor

Post by wansf » Mon Jul 08, 2019 11:03 am

epic :eek:
will u keep adding more key in the future?

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Re: NetEase NPK (EXPK) Archive Decryptor

Post by Bigchillghost » Tue Jul 09, 2019 10:01 am

Update:
Fixed a stupid bug that cause the decryption failed with Onmyoji Arena. Added support for Win XP.
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Re: NetEase NPK (EXPK) Archive Decryptor

Post by Bigchillghost » Tue Jul 16, 2019 12:24 pm

Update:
Fixed another bug that introduced by previous fix. Sorry about that. :lol:
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Re: NetEase NPK (EXPK) Archive Decryptor

Post by Bigchillghost » Sat Aug 10, 2019 4:42 am

Update:
1. Changed the detecting method to adjust with different version games;
2. Fixed an issue for decrypting MARVEL Super War.
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Re: NetEase NPK (EXPK) Archive Decryptor

Post by Bigchillghost » Wed Jan 15, 2020 10:43 am

Update:
Added a longer xor key. Check the first post for details.
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Re: NetEase NPK (EXPK) Archive Decryptor

Post by Bigchillghost » Fri Jan 17, 2020 5:23 am

Update:
1. Another update to the long key: now approximately 1155 KB;
2. Updated decryptor to v0.4.1 for better perfomance;
3. Added encryption key for Marvel Super War above v2.6.0.

Check the main post for details.
Last edited by Bigchillghost on Wed Jan 22, 2020 7:44 am, edited 1 time in total.
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Re: NetEase NPK (EXPK) Archive Decryptor

Post by Bigchillghost » Tue Jan 21, 2020 6:47 pm

Update:
1. Ultimate update to the long key for Onmyoji Arena and Marvel Super War (below v2.6.0): now approximately 9414 KB;
2. Updated decryptor to v0.4.2: added real-time status message during decryption.

The key for MSW above v2.6.0 hasn't been updated yet.
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Re: NetEase NPK (EXPK) Archive Decryptor

Post by Bigchillghost » Thu Jan 23, 2020 2:36 pm

Update:
Added longer key for MSW above v2.6.0: 1915 KB approximately. Sufficient for every high res character package.
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Re: NetEase NPK (EXPK) Archive Decryptor

Post by BlueEffie » Thu Feb 20, 2020 3:02 pm

I found the decryption method and key of [Forever 7 Day's Capital] [Onmyoji Arena] [Marvel Super War] in IDA Pro :D

This is the decryption code fragment written by C#. Just decryption without extraction
NPKDecrypt.rar
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Re: NetEase NPK (EXPK) Archive Decryptor

Post by Bigchillghost » Fri Feb 21, 2020 7:59 am

BlueEffie wrote:
Thu Feb 20, 2020 3:02 pm
I found the decryption method and key of [Forever 7 Day's Capital] [Onmyoji Arena] [Marvel Super War] in IDA Pro :D
Congratulations!

I've updated the xorkeys generated with the method you posted. :D
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Re: NetEase NPK (EXPK) Archive Decryptor

Post by Untily » Thu Jun 11, 2020 10:08 am

Thank you [roll]

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Re: NetEase NPK (EXPK) Archive Decryptor

Post by m545891031 » Sat Jun 13, 2020 10:37 am

Bigchillghost wrote:
Fri Feb 21, 2020 7:59 am
BlueEffie wrote:
Thu Feb 20, 2020 3:02 pm
I found the decryption method and key of [Forever 7 Day's Capital] [Onmyoji Arena] [Marvel Super War] in IDA Pro :D
Congratulations!

I've updated the xorkeys generated with the method you posted. :D
Unable to get the file name when decompressing using QuickBMS script, does it mean that using this tool can get the correct name when decompressing NPK? :o

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