MITM faking certificates

I am looking at the theory behind MITM attacks in order to see some unencrypted packets from the 3DS. From research here is what I understand so far:

3DS > Proxy > Nintendo server

I am going to try and force the 3DS to use a forged certificate. The 3DS will then communicate with the proxy and the proxy will decrypt the packets, see whats there, re-encrypt them and then send it out to the Nintendo server. I see an issue though, the Nintendo server is expecting to see the original 3DS public certificate from the proxy server but it wont as I do not have it. Is it possible for me to get the original certificate from the 3DS before giving it the forged one?

Here is my idea:

1. start send packets from 3ds, original cert is sent from 3ds to proxy, which is stored


2. insert forged cert to 3ds


3. connection is reset

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1. using forged cert, start communication, fake cert speaks with proxy server


2. proxy decrypts packets from 3ds, logs them, re-encrypts them


3. uses the old certificate to communicate with the Nintendo server then forward packets

Is this feasible. Is there an easier way? I know some of them are hard (insert forged cert to 3DS). Which tools can help me accomplish this?