How is a DH key used in TLS-ECDHE-RSA?
In the “server key exchange” packet for TLS-ECDHE-RSA, there is a DH key with RSA signature. The RSA signature for the “dh key” and “certificate” is used for authentication purposes / digital signature for the server to prove it is who it claims to be. “RSA public key” in the certificate, for TLS-RSA, is used by the client to encrypt the PMS.
What’s the difference between a DH certificate and a RSA signature?
The RSA signature for the “dh key” and “certificate” is used for authentication purposes / digital signature for the server to prove it is who it claims to be. “RSA public key” in the certificate, for TLS-RSA, is used by the client to encrypt the PMS.
Can a DHE key be used on a permanent server?
That’s one of the points of DHE: the actual key exchange uses newly generated DH key pairs, which neither client or server stores anywhere except in its own RAM. Having a copy of the permanent server’s key would give you nothing, as a passive attacker with Wireshark, since it is used only for signatures.
What does RSA stand for in cipher suite?
“RSA” in the cipher suite refers to the random DH public key signature, but not the certificate signature “RSA” refers to both DH key signature and server certificate’s public key. The keys used to sign/verify the DH public key come from certificate exchange, or we can’t make sure we’re using the actual public key of the server.
How big can a RSA key be without dhe?
In practice, RSA and DH keys which are way too small (smaller than 512 bits) will be rejected by many implementations (and when using RSA key exchange without DHE, there is an absolute minimum of 465 bits for the RSA modulus, otherwise the key exchange cannot take place at all).
What is the pubkey length of dhe-RSA with sha384?
Successful and failed connections all settle upon Cipher Suite TLS_DHE_RSA_WITH_AES_256_GCM_SHA384 (0x009f) in the Server Hello. All connection attempts reach Server Hello Done and failed connections are FINned by the client immediately following that.