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[476793556]

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[LexNastin]

If I were to guess, I’d say that the problem is more than likely in your implementation. Specifically, the car is unable to decrypt your message. Perhaps you sent something wrong somewhere? Or maybe you encrypted with the wrong nonce? Perhaps you incremented the nonce integer but in are still using the original nonce array for encryption?

There isn’t enough context for me to help you much further, unless you send some code or something. Hope this helps.

[LexNastin]

Also, no your ephemeral key didn’t change. I was testing for the past 2 years and am yet to see it change from the original value.

[476793556]

Thank you very much for your answer, which is enlightening to me. I also suspect that there is an error in the nonce recorded by myself. I will read your document again and test whether there is any instruction that can synchronize the nonce, so as to ensure that the nonce stored locally is consistent with that of the vehicle.

[LexNastin]

What the problem here probably is if it’s the nonce isn’t that you’re sending a used nonce. No - the car would notify you of that. The problem is that you might be encrypting the message with a different nonce than you’re telling the car you’re encrypting with.

[476793556]

Hi, My encryption method was initially working fine, I could control the vehicle. However, after using it for some time, it would become ineffective. Previously, you suspected a problem with the counter, so I added a logic that when it becomes ineffective, it would request the counter from the vehicle and increment it by 1 for the next command. When the app starts, I obtain the counter from the vehicle and send the following command:

<ToVCSECMessage 0x282961800>: {
unsignedMessage {
InformationRequest {
informationRequestType: INFORMATION_REQUEST_TYPE_GET_COUNTER
keyId {
publicKeySHA1: "\340\247MO"
}
}
}
}

Upon successful execution, the vehicle responds with:

<FromVCSECMessage 0x13f6072d0>: {
sessionInfo {
counter: 255
}
}

At the same time, I also request the vehicle's status by sending:

<ToVCSECMessage 0x2829476c0>: {
unsignedMessage {
InformationRequest {
keyId {
publicKeySHA1: "\340\247MO"
}
}
}
}

The vehicle responds with:

<FromVCSECMessage 0x13f304080>: {
vehicleStatus {
vehicleSleepStatus: VEHICLE_SLEEP_STATUS_AWAKE
}
}

The problem arises when I send a command, such as opening the trunk:

<ToVCSECMessage 0x282948ba0>: {
signedMessage {
protobufMessageAsBytes: "\253_\206\260"
signature: "\216J\270\205v:\251(\254/H\332\242\2747;"
keyId: "\340\247MO"
counter: 256
}
}

At this point, I receive the following response:

<FromVCSECMessage 0x13f40b560>: {
commandStatus {
operationStatus: OPERATIONSTATUS_ERROR
signedMessageStatus {
counter: 256
signedMessageInformation: SIGNEDMESSAGE_INFORMATION_FAULT_AES_DECRYPT_AUTH
}
}
}

I also receive:

<FromVCSECMessage 0x13f304080>: {
sessionInfo {
publicKey: "\004#\315\0230\374\3657\371\241Ju\367\320\346\020\266z\303p'\322\206PS\267\304\027m\203\236\023\332\364\307\p0\320W\370\260\254\202Y\\026`r\261\346\223s(\356\256\005\264kH\320\335\033{y"
}
}

In other words, even though I synchronize the vehicle's counter, it does not solve the issue of ineffectiveness. Currently, I am at a loss, can you identify any problems from the provided information? I look forward to your response.

[476793556]

I found the problem and have fixed the bug now, thank you