Explanation : Kruskal’s algorithm follows greedy approach in order to find MST of a connected graph. Quick sort follows divide and conquer strategy. Floyd Warshal algorithm is used to find the shortest path between every pair of vertices and it follows dynamic programming strategy.
Explanation : First you know what is Birthday attack :
by Using Birthday Attack, some fraudulent message can be generated which has same hash value and digital signature as the original message.
I. Instead of intended message, Sender can take some fraudulent message and encrypt it with own private key and then receiver’s public key. This is POSSIBLE. II. Third party don’t have that Private Key to encrypt the message. So this is NOT possible. III. And the same way R also don’t have that Private key to encrypt the message.
So, the only possibility is – (I) S can launch a birthday attack to replace m with a fraudulent message.
Option (B) is correct.