question archive Imagine a peer-to-peer network where 1000 users want to communicate in an authenticated and confidential way without a central Trusted Third Party (TTP)

Imagine a peer-to-peer network where 1000 users want to communicate in an authenticated and confidential way without a central Trusted Third Party (TTP)

Subject:Computer SciencePrice:3.87 Bought7

Imagine a peer-to-peer network where 1000 users want to communicate in an authenticated and confidential way without a central Trusted Third Party (TTP).

1. How many keys are collectively needed, if symmetric algorithms are deployed?

2. How are these numbers changed, if we bring in a central instance (Key Distribution Center, KDC)?

3. What is the main advantage of a KDC against the scenario without a KDC?

4. How many keys are necessary if we make use of asymmetric algorithms? Also differentiate between keys which every user has to store and keys which are collectively necessary.

pur-new-sol

Purchase A New Answer

Custom new solution created by our subject matter experts

GET A QUOTE

Answer Preview

Answer:

1) If symmetric algorithms are deployed then number of keys needed=(n*(n-1))/2 =((1000*999)/2)=499500.
where n is number of users.
2) A secret key is established between KDC and each user.
   If KDC is not used then number of keys is of O(n^2).
   If KDC is used then number of keys is of O(n).
3) The main advantage of KDC : number of keys generated are greatly reduced and also reduce the risks inherent in exchanging keys.

4) If we use assymetric algorithms number of keys required are 2*n=2*1000=2000 keys.
2 for each user.
one is a public key which is know to other users and a secret key which only user knows about it.