Two users wish to establish a secure communication channel and exchange a session key after mutual authentication. Show how this can be done with the hclp of a $\mathrm{KDC}$ .

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Two users wish to establish a secure communication channel and exchange a session key after mutual authentication. Show how this can be done with the hclp of a $\mathrm{KDC}$ .

written 4.8 years ago by

teamques10 ★ 64k

• modified 4.8 years ago

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written 4.8 years ago by

teamques10 ★ 64k

Key Distribution Center (KDC) is a central authority dealing with keys for individual computer ( nodes) in a computer network.
- It is similar to the concept of the authentication Services (AS) & Tichel Granting Service (TGS) in Kerheros.
- The basic idea is that every node shares an unique secret key with the KDC. Whenever user wants to communicate securely with user B , the following action take place.
- The background is that A has a secured secret key KA with KDC . Similarly B is assumed to share a secret key KB with the KDC.
- A sends a request to KDC encrypted with KA , which includes:
- Identifies of A & B
- A random number R , called as names.
- KDC responds with a message encrypted with KA , continuing :
a. One - time symmetric key KS.

b. Original request that was sent by A, for verification

c. Plus, KS encrypted with KB & ID of A encrypted with KB.
- A & B can now communicate by using KS for encryption

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