A sender S sends a message m to receiver R. which is digitally

Home » Computer Networks » Computer networks miscellaneous » Question

A sender S sends a message m to receiver R. which is digitally signed by S with its private key. In this scenario, one or more of the following security violations can take place.
(I) S can launch a birthday attack to replace m with a fraudulent message.
(II) A third party attacker can launch a birthday attack to replace m with a fraudulent message.
(III) R can launch a birthday attack to replace m with a fraudulent message.
Which of the following are possible security violations?

1. (I) and (II) only
2. (I) only
3. (II) only
4. (II) and (III) only

Correct Option: B

For security violations, sender S can launch a birthday attack to replace message (m) with a fraudulent message because he has the signature and he can decrypt the signature by his own public key and get’s the hash value, with that same hash value, he can create another message and can be sent instead of original. Hence option (b) is correct.