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More specific is server public key exchange is encrypted? If yes how can client decrypt server's public key?

maddy10
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You seem very confused.

  • The premaster secret is not exchanged. It is sent by the client.
  • The server public key is not exchanged. It is sent by the server, in the certificate contained in the Certificate message.
  • Unless there has been a prior handshake, nothing is encrypted until the ChangeCipherSpec message has been issued.
  • That message is issued several steps after the premaster secret is sent.
  • The server public key is not a secret and does not need to be encrypted.
  • Unless the cipher suite is a DSA one, the client doesn't need the server's public key at all.
user207421
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    Thanks for quick response. – maddy10 Aug 12 '16 at 12:43
  • 1,2 correct for plain-RSA, but DHE and ECDHE (aka PFS) are now at least as common; 4 client CCS is immediately after ClientKX unless client-auth which is rare and server CCS is first in its response unless ticket which is also rare; 6 I don't know what you mean but client needs at least one server publickey (often two) for anything but pure SRP, pure PSK, or Kerberos, all of which are rare. – dave_thompson_085 Aug 13 '16 at 13:45