The actual question is:
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 mm 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?
A. (I) and (II) only
B. (I) only
C. (II) only
D. (II) and (III) only
so if a sender sends a message m to reciever.. I know that an attacker can perform a birthday attack and send fraudulent message to receiver
But these statements confuse me!
Sender can perform birthday attack and send fraudulent message to Receiver
Receiver can perform birthday attack and create fraudulent message.
I searched upon this but this is too confusing can someone explain? They both seem to be true but the answer i saw states only one is? Can someone explain birthday attack! Thanks