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How mandatory STARTTLS (on Google servers' side) would help you against MitM downgrade attack? The only way to avoid it is for your MUA to require STARTTLS.
by drdaeman 11y ago
How mandatory STARTTLS (on Google servers' side) would help you against MitM downgrade attack?
The only way to avoid it is for your MUA to require STARTTLS.
- cm2187 11y agoOr for the server to terminate the connection if STARTTLS is not requested
- drdaeman 11y agoYes, but how that'd prevent the attack? The active attacker may tell your MUA to use the plain text, but this doesn't mean the whole connection must be unencrypted end-to-end. I don't see why the connection past the attacker can't still use STARTTLS (or even "classic" port-based TLS). Google servers won't even know the connection is not secured end-to-end. That said, requiring TLS/STARTTLS on the server side is a good idea. But it doesn't protect from downgrade attacks.