It could mean somebody else can, because of key escrow and partial key escrow. Even if the key is generated on the device and stays on the device, you have to look at how the key is generated. With key escrow, the messages can be secure against attacks by everyone except those who have the escrowed portion of the key.
And to do that you mustalso transmit the escrowed part of the key in the protocol -- which is 100% detectable as a blob of "extra but seemingly unnecessary data".
Do you see that? Does anybody see that? Has anybody seen that?