Emulation HTTPS Decryption through Cemu

Ep8Script

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Hey there!

I was just wondering, is it possible to use Fiddler to decrypt https traffic from games such as Mario Maker running through Cemu? I'm just wondering if there's any way to get it to go through Fiddler's proxy, and which certificates to trust. Thanks!
 

Hiccup

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Note: You have to have cemu configured for online play. There are other tutorials for this.
  • In Fiddler, open Tools > Options
  • In the HTTPS tab turn on HTTPS Connects
  • Enable HTTPS decrypting
  • Ignore server certificate errors
  • Back in the HTTPS tab click Actions > Export Root Certificate to Desktop
  • Rename the just exported FiddlerRoot.cer to CACERT_NINTENDO_CA_G3.der
  • Replace cemu/mlc_01/vol/storage_mlc01/sys/title/0005001b/10054000/content/scerts/CACERT_NINTENDO_CA_G3.der with the just renamed file. Backup the original for convenience, but you can download it from NUS or get it from an unmodified Wii U.
  • Copy cemu/mlc_01/vol/storage_mlc01/sys/title/0005001b/10054000/content/ccerts/WIIU_COMMON_1_CERT.der to %USERPROFILE%\[My ]Documents\Fiddler2\ and rename it to ClientCertificate.cer
(source: RedDucks)
 
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RedDucks

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Yes it is more than possible, we have been sniffing the traffic from both Cemu and physical WiiU's for a long time now while working with Nintendo's servers. Just follow the steps above by @Hiccup and you should be fine.

Side note, since you specifically mentioned Super Mario Maker you might find this interesting https://github.com/RedDuckss/csms which is a repo where we dumped our research on SMM.

Out of curiosity, why do you want to sniff traffic?
 
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GRAnimated

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What Hiccup replied with will work, but me, Hiccup, RedDucks, and mrjvs have already gone through all of SMM and documented all of the URLs and generating methods. You can see the documentation here: https://github.com/RedDuckss/csms
The only issue we have is generating the URL signature without a key to generate URLs.
 
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Ep8Script

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Oh okay, very cool everybody. Thanks for the help!

I'm just generally interested in it. For some reason I could never get it to work but this was very helpful! I'll definitely check out your research too.
 

Ep8Script

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I folllowed the instructions and unfortunately I couldn't get it to work. :(

It's alright I guess. It's not super important, but thanks for the help!
 

RedDucks

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I folllowed the instructions and unfortunately I couldn't get it to work. :(

It's alright I guess. It's not super important, but thanks for the help!
What exactly was the error. We have been using those steps above for our research for a while now, we can confirm they work.
 

Ep8Script

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What exactly was the error. We have been using those steps above for our research for a while now, we can confirm they work.
I honestly don't know. I first tried Mario Maker and I just got infinite loading, and then I tried Mario Kart 8 just as a test and I got error code 106-0502.
 
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Ep8Script

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Are you able to go online normally, without the proxy stuff?
Yeah it works fine without the Fiddler certificate in there.

I noticed I get the same error code in SMM as well. I might try a remote PC and see if that makes any difference (which maybe I was meant to do in the first place?).

--------------------- MERGED ---------------------------

Unfortunately using a remote PC and it's certificates didn't work either... not sure what's wrong but thanks for your help anyway.
 
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