SSL - Different procedures to authenticate Server and Client

[pwilbert () uninet com br]

Hi,

Why SSL use different procedures to authenticate the Client
(see 
below) and the Server (see below)? Why the Server do not
need to digitally sign a msg to prove it is whom is claiming
to be? 

Client Authentication: "Does the user's public key 
validate the user's digital signature? The server checks 
whether the user's digital signature can be validated with 
the public key in the certificate. If so, the server has 
established that the public key asserted to belong to the 
user matches the private key that is used to create the 
signature and that the data has not been tampered with 
since it was signed"

Server Authentication: "Does the domain name in the 
server's certificate match the domain name of the server 
itself? This step confirms that the server is actually 
located at the same network address that is specified by 
the domain name in the server certificate. Although step 4 
is not technically part of the SSL protocol, it provides 
the only protection against a form of security attack 
known as a "Man-in-the-Middle Attack." Clients must 
perform this step and must refuse to authenticate the 
server or establish a connection if the domain names do 
not match. If the server's actual domain name matches the 
domain name in the server certificate, the client goes on 
to step 5."

Thanks,

Paulo.


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