How many keys are needed for encrypted communication among 16 persons using…

2025

How many keys are needed for encrypted communication among 16 persons using AES encryption assuming unique key is used between any two persons:

  1. A.

    120 keys

  2. B.

    256 keys

  3. C.

    53 keys

  4. D.

    216 keys

Attempted by 6 students.

Show answer & explanation

Correct answer: A

To find the number of keys needed for encrypted communication among 16 persons using symmetric encryption (AES), we calculate the number of unique pairs. Each pair requires a distinct shared key. Using the combination formula n(n-1)/2 where n=16: (16 * 15) / 2 = 120. Therefore, 120 unique keys are needed.

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