Alice and Bob shared an n-bit secret key some time ago. Now they are no longer...

 

 

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Alice and Bob shared an n-bit secret key some time ago. Now they are no longer sure they still have the same key. Thus, they use the following method to communicate with each other over an insecure channel to verify that the key KA held by Alice is the same as the key Ka held by Bob. Their goal is to prevent an attacker from learning the secret key. 1. Alice generates a random n-bit value R. 2. Alice computes X - KA (XOR) R, where (XOR) denotes the exclusive-or boolean function, and sends X to Bob. 3. Bob computes Y- Ka (XOR) X and sends Y to Alice. 4. Alice compares R and Y. If R-Y, she concludes that KA KB. that is, she and Bob have indeed the same secret key. Show how an attacker eavesdropping the channel can gain possession of the shared secret key. Alice and Bob shared an n-bit secret key some time ago. Now they are no longer sure they still have the same key. Thus, they use the following method to communicate with each other over an insecure channel to verify that the key KA held by Alice is the same as the key Ka held by Bob. Their goal is to prevent an attacker from learning the secret key. 1. Alice generates a random n-bit value R. 2. Alice computes X - KA (XOR) R, where (XOR) denotes the exclusive-or boolean function, and sends X to Bob. 3. Bob computes Y- Ka (XOR) X and sends Y to Alice. 4. Alice compares R and Y. If R-Y, she concludes that KA KB. that is, she and Bob have indeed the same secret key. Show how an attacker eavesdropping the channel can gain possession of the shared secret key.

Answer rating: 100% (QA)

If an attacker is eavesdropping on the channel between Alice and Bob they can potentially gain posse... View the full answer