No secure communication in Symmetric Key cryptography

[Shiva$m]

Hello friends, I wanted to know how I can secure a communication in symmetric key cryptography. I think that it is not possible in symmetric key cryptography but still I am not sure. I want to know whether it is possible or not. If it is then how can I achieve it? Will it be using the same key in encryption and decryption process or different key? If anybody having any information about this question then please let me know as soon as possible.

[Sabastiaan]

As in case of symmetric key cryptography, the key that has to be used for both encryption and decryption should be the 'same' this leads to a problem that how the two parties requiring secure communication can 'agree' or 'decide' upon a common key, without letting any third person know about it? There can be many ways in which the two parties will try to communicate assuming it is secure, but it may not be so. e.g. even if they exchange letters, seal envelopes into locked boxes, talk over open media for the common key, or send the key along with the locked boxes, whatever may be the means used, it turns out to be practically non-viable or difficult to implement.

[teenQ]

That is to say, there are very much chances of intercepting the communication between two parties if any of these methods are used. Then you can call it as a problem of key distribution. I think that the main solution to this problem is that it should use another key exchange algorithm which is also popularly known as diffie- hellman key exchange algorithm. This is the best solution to secure communication in a symmetric key cryptography.

[Pabloa]

I also completely agree with this point that you need to use a diffie hellman algorithm in order to secure a key exchange in symmetric key cryptography. One should know that key which we are using must be used in both the process which are encryption and decryption. If one key is used in both the process then how can you assume that it is secured. In order to obtain a secured communication in symmetric hey cryptography, I think that diffie hellman key algorithm is the best option.