[users@httpd] Alternative for Apache webserver Diffie-Hellman encryption to permit SSL decryption

[sunhux G <su...@gmail.com>]

I'm newbie to encryption & beginner to Apache.


Length: 81
Handshake Protocol: Server Hello
  Handshake Type: Server Hello (2)
  Length: 77
  Version: TLS 1.0 (0x0301)
  Random
     gmt_unix_time: May 23, 2011 11:01:51.0000000000
     random_bytes: C0C48BA2.....
   Session ID Length: 32
   Session ID: 53283989...
   Cipher Suite: TLS_DHE_RSA_WITH_AES_256_CBC_SHA (0X0039)    <==

Above is an extract of a data traffic sniffed using a product which
I'm evaluating.

I have a requirement to use a sniffing product (which I connect to our
internal LAN) to capture users access to our website portal to check
which pages the user access & the time a user login / logout &  SSL
https encryption is involved.  However, to do this, I'll need to do
decryption.

My Apache web servers appear to be configured to use "Diffie-Hellman"  key
exchange.  This can be verified by looking at the Server Hello packets and
viewing the Cipher Suite (as shown in above traffic capture).  "DHE" means
Diffie-Hellman key exchange.

I suppose this means the shared private key from the web server is not used.
In Diffie-Hellman key exchange, the private key for each session is created
dynamically between the client and server, and is therefore technically
impossible to decrypt : correct me if I'm wrong.  Refer to links / urls below
 on why DH key exchange makes SSL decryption impossible:
 - http://www.unleashnetworks.com/blog/?p=28
 - http://wirewatcher.wordpress.com/2010/07/20/decrypting-ssl-traffic-with-wireshark-and-ways-to-prevent-it/

In my Apache config file, there's a line below:
SSLCipherSuite HIGH:MEDIUM:!aNULL:+SHA1:+MD5:+HIGH:+MEDIUM


Question:
Which alternative cipher provides the same encryption/key strength -
just doesn't use Diffie-Hellman for key exchange?

How should I amend my Apache config file so that it replaces Diffie-Hellman
with this new encryption?  Pls provide as precise the instruction as possible
& whether I need to do "service httpd restart" or "service httpd reload"?

Any alternative proposed should not flag out as vulnerability during a
vulnerability scan.


Then I would be able to use the promiscuous mode sniffing device to see a
user logins & the slow pages that he accessed etc


Thanks

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[users@httpd] Re: Alternative for Apache webserver Diffie-Hellman encryption to permit SSL decryption

[sunhux G <su...@gmail.com>]

Note that in my current Apache config file, there's a line below which does not
mention anything on Diffie-Hellman, so my guess is Apache must have selected
/enabled DH by default.  How can I explicitly turn it off?
    SSLCipherSuite HIGH:MEDIUM:!aNULL:+SHA1:+MD5:+HIGH:+MEDIUM

I'm thinking of using TLS_RSA_WITH_AES_256_CBC_SHA
encryption.  Kindly advise what's the syntax to put into the
Apache .conf file.

Any security consequence or network performance impact
from using this new encryption?

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