20.9 Summary
In this chapter, we covered attacks on TLS Handshake protocol. Since Alice and Bob use the handshake to establish the shared MasterSecret for their current TLS session, any successful attack on the handshake completely breaks the security of that TLS session.
While we looked into the attacks’ details, there are also some general lessons to be learned from these attacks. Downgrade attacks provide a practical example on how the presence of insecure configuration options and, on a more general level, legacy options kept for backward compatibility, can easily undermine security.
SLOTH illustrates that outdated cryptographic primitives are dangerous not only in theory, but also in practice. Intuitively, one might be tempted to think that theoretical weaknesses are difficult – or even impossible – to exploit in practice. SLOTH shows that a clever attacker is able to get around these difficulties.
Padding oracle attacks such as Bleichenbacher and its numerous...
