Hi,

Few questions on OpenSSL.

1. Cipher Selection:
If the Client sends a weaker cipher (export), followed
by a stronger cipher, then openssl selects the first
(weaker) cipher as preferred by the client (as per the
RFC). 

Note in the above case, an attacker can influence the
order of client's cipher preference, thereby causing
the peers to decide on weaker ciphers.

Shouldn't there be logic to protect from such attacks?
Given a set of ciphers, the server should be able to
decide on the most strongest one, need not be the
first one always.

2. In s3_servr.c, after server sending the
hello-request (SSL3_ST_SW_HELLO_REQ_A) we change state
to "SSL_ST_OK" in SSL3_ST_SW_HELLO_REQ_C. 

Isn't the hello-request message followed by Client
sending "Client-Hello" message. In that case the state
should be changed to SSL3_ST_SR_CLNT_HELLO_A. 

3. What should be ideal response (RFC) of server in
this situation:
"Server has only SSLv2 support and Client comes with
SSLv3 Client-hello."

Currently openssl terminates such connections. 

4. session->peer cert refers to client certificate
used in Client-Authentication. Is it required to store
this cert once the session is establish?

The main purpose of this cert is to authenticate
client and verify the client's Certificate-Verify
message.

Once this is done, is it okay to free the cert. In
session re-use there is no exchange of client's cert
or cert-verify message.

Eventually too many peer certs may hog-on server
resources.

Pl. comment on this.

5. For SSLv2 is it mandatory for server to send a
valid session-Id even if server is not willing to do
session-reuse?

For SSLv3/TLSv1 server can inform this by sending a
NULL session-ID. But sending NULL session-id for SSLv2
doesn't seem to work.

Thanks,

Tushar.





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