As we know that Cryptography is based upon the encryption of the message at the sender side followed by its decryption at receiver side. This encryption and decryption is done by using a key. There are two keys, one at the sender side and one at the receiver side. In the key exchange Cryptography technique some information is exchanged between the source and the destination from time to time and ultimately the sender side key is exchanged with the receiver side key. So, we can say that the key exchange algorithms follow the symmetric key Cryptography approach as the keys used on both sender and the receiver sides are same.
One such example of key exchange Cryptography technique is the Diffie-hellman (DH) algorithm which was developed in 1976 by Diffie and Hellman. It soon reached new heights in the field of Cryptography. This method allows for the sharing of key between two users without any prior communication. The users do not have to meet to agree on the key, it can be achieved through a medium like internet. This shared key is kept secret from the outside world. The Diffie-hellman algorithm uses the discrete logarithm problem for providing the security. As this algorithm involves logarithmic calculations, so it is quite hard to crack, contributing towards its huge success.
The methodology involved in this algorithm is that, if two parties A and B want to communicate, then the firstly they will have to choose their private numbers. After that they have to calculate their public keys by using their private values and applying some logarithmic calculations, then these public keys are exchanged between A and B. Finally both A and B generate their secret keys. These secret keys of both A and B are found to be the same. So, that’s how communication is done in shared key environment.
Usually the Diffie-hellman algorithm is very good but sometimes it becomes vulnerable to the man in the middle attack. The cause of this attack is due to the fact that Diffie-hellman method does not checks the authenticity of the users. One of the probable solutions of this problem can be the use of Digital Signatures. Later on in the year 1992, the authenticated Diffie-Hellman model came which used the concepts of Digital Signatures and public key certificates. This new algorithm was completely immune from the man in the middle attack problem.
by Camila 1 year ago
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