Login credentials and session id security

Hi All,

Can someone please tell what is the most secure way of sending login 
credentials to the server. The possible ways that I am familiar with are:

- get method
- post method
- hidden form fields

By using an encrypted connection we cannot sniff the credentials, but 
still it is very easy to capture or manipulate these credentials 
using a web proxy from any of these methods. So I am looking to find 
a method to transport the credentials to the server so that the 
security of these credentials can't be compromised even by deploying 
a web proxy.

Also once a session id is generated, what is the best way to maintain 
the security of a session id.

Any help would be much appreciated.

Regards
Vishal


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