[sandeepkd]

You are already doing a MITM, so some one is placing the trust in you as a intermediary. In reality the content distribution networks fronting any of the API operations have already muddied the water at this point. You are well into your rights to recalculate the signature for the payload and replace it with the secret key.

[neo2006]

yes I agree and we actually already do that for TLS when rewriting secrets after encryption but my point is about the fact in our threat model we consider the app as an adversary so we don't want to use any of its buffers to rewrite secrets because it would be trivial for an adversary to reread the buffer after rewrite and get the secret. The way we overcome this is by listening to the user buffer recording all the data we need to rewrite the secret without writing anything. We go back later in the kernel buffer meant to be sent to the network and not accessible to the user app and perform the rewrite. For API keys used to sign the request we need to do something similar which could be challenging within ebpf (maybe doable I'm not sure)