[TLS] draft-rescorla-tls-renegotiate and MITM resistance

[Yair Elharrar <Yair.Elharrar at audiocodes.com>]

The proposed draft is intended to resolve an MITM attack scenario, but is the new extension tamper-resistant?

Since the MITM handles all traffic between the real client and real server, it could add a fake extension to the 2nd ClientHello with its original verify_data, and empty the returned extension in the ServerHello.

In addition, until such time that all clients in the world start supporting this extension (e.g. kiosks in airports), servers will have to support backward compatibility. The MITM can downgrade every client by simply removing the extension from the ClientHello.

        Yair


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