Suppose that everyone in a group of N people wants to communicate

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Suppose that everyone in a group of N people wants to communicate secretly with the N-1 others using symmetric key cryptographic system. The communication between any two persons should not be decodable by the others in the group. The number of keys required in the system as a whole to satisfy the confidentiality requirement is

1. 2N
2. N(N - 1)
3. N(N - 1)/2
4. (N - 1)2

Correct Option: C

In Symmetric Key Cryptography, if 'N' number of users is keen to partake, then N (N - 1) / 2 number of keys is required to satisfy the confidentiality requirements of any users.