Question

Critical Thinking 3-7: Diffie-Hellman Research

How does Diffie-Hellman work? Use the Internet to research this this key-sharing function. Then visit the website dkerr.home.mindspring.com/diffie_hellman_calc.html to see how values are created. Write a one-page paper on Diffie-Hellman.

Answer 1

Diffie-Hellman

Diffie-Hellman , it is also called the exponential key exchange this basically a method of the digital encryption .It is a method in which the two computer users generate a shared private key with that they can exchange the information across an insecure channel.In other word we can also define it as a method by which a secure cryptographic keys are exchanged over a public communications channel.In this basically keys are not exchanged they are basically jointly derived.It is mostly uses for the key exchange.

Advantages of the Diffie Hellman :

• In this the sender and receiver not need any prior knowledge of each other.
• In this the sharing of the secret key is safe.
• When the keys are exchanged once, the communication of the data not done through insecure channel.

The main purpose of the Diffie-Hellman protocol is that it enable the two users to exchange a secret key securely and that key are used for the subsequent encryption of messages. This key exchange protocol is the earliest practical example of the public key exchange , that are implemented in to the field of cryptography.This key exchange protocol are Published by the Diffie and Hellman in 1976.In this key exchange protocol if the two parties that have not any prior knowledge bout each other they can establish a shared secret key over an insecure channel jointly.Then after this key can be used to encrypt the subsequent communications by the using of a symmetric key cipher.By the help of the Diffie–Hellman key exchange we can secure a variety of Internet services. By this we can secure our system by remotely access from another computer, and also for ending encrypted emails.

How does Diffie-Hellman work?

As we know that the Diffie-Hellman algorithm used to establish a shared secret between two parties. This is basically uses a method of cryptography keys exchange for the use of the symmetric encryption algorithms.This algorithm are little bit complex , So Let's understand the working by an example:Suppose Ram and Ramesh are two person that Ram want to establish a shared secret with Ramesh:

1. In advance , Ram and Ramesh are agree on a prime number, p, and a base, g.In this example, let's assume that p=23 and g=5.
2. Now , Ram choose a secret key a, that the value of a is 6, and after computing A = g^a mod p.In this example we get the value of A=8.
3. Let's suppose Ramesh choose b secret integer whose value is 15 , and after computing B = g^b mod p we gat B value as 19.
4. Ram sends A to Ramesh and Ramesh send B to Ram.
5. To get the shared secret, Ram computed the s = B^a mod p.In our example the Ram obtain the value s=2.
6. To get the shared secret , Ramesh computes the s = A^b mod p. In our example the Ramesh obtain the value s=2.

By all this steps we see that to obtain the value of the  the values of a and b, we required to derive the value of s , But the value of s not transmitted at all.

THANKS, i think this will give you a better intuition about your question. If you have any doubt feel free to ask in the comment section.