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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. There's also a long version key where the first 0x146277 bytes (1304 KB) of it are definitely correct and the results of those larger than that do seem OK though. So use it on your own risk.

- About Encryption Key:
The two games above use simple xor for encryption, but with an infinite fixed sequence as key. The original key (871 KB) mostly was taken from this page (credit to zhouhang95). The key provided 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). Without knowing the method of how the key is computed, this might be the easiest solution.

EXPKDec.zip
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Last edited by Bigchillghost on Thu Jan 23, 2020 2:29 pm, edited 9 times in total.
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Re: NetEase NPK (EXPK) Archive Decryptor

Post by heyongqing19980227 » Sun Jul 07, 2019 4:42 pm

thank you
Last edited by heyongqing19980227 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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