An eavesdropper always faces a locked box, and a key point is that the locking m

Question

An eavesdropper always faces a locked box, and a key point is that the locking mechanisms of Alice and Bob commute—Alice can remove her padlock, even though Bob put on his padlock later. Let us try to implement this protocol over a network using encryption with one-time pads that are XORed with the plaintext message m (which we represent as a bitstring of some fixed length k):

Alice takes the message and forms a cipher with a random bit stream and sends cipered message to Bob.

Bob recieves the message, picks a random sequence, encrypts, and sends it back to Alice.

Alice computes cipher and sends this value to Bob.

Bob computes the message.

Explain why this protocol is insecure, even if the adversary only eavesdrops passively and never sends or deletes messages

Explanation / Answer

This network is not safe because here Bob picks up his private key randomly Alice needs Bob's private key to decrypt the message sent by Bob. But any intruder can randomly try to find out the private key of Bob or Alice and can manuplte the message.

the Xored message can be decrypted using Xand the message. and can be easily decrypted.

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.