One of the approaches below is ”secure”. For each approach, state Secure or Insecure, and explain why that approach does or does not achieve the two desired notions of confidentiality described above. (a) Aldebaran computes c = Enc(pkB , m) and broadcasts (pkB , c). Borealis observes the broadcast containing their public key and obtains the message as m = Dec(skB , c).
Question
One of the approaches below is ”secure”. For each approach, state Secure or Insecure, and explain why that approach does or does not achieve the two desired notions of confidentiality described above. (a) Aldebaran computes c = Enc(pkB , m) and broadcasts (pkB , c). Borealis observes the broadcast containing their public key and obtains the message as m = Dec(skB , c).
Solution
Secure. This approach achieves the two desired notions of confidentiality. First, it ensures that only the intended recipient (Borealis) can decrypt the message, as they are the only one with access to the corresponding private key (skB). This is known as confidentiality under chosen plaintext attack (CPA). Second, it also ensures that an eavesdropper cannot learn anything about the message, even if they know the public key and see the ciphertext. This is known as confidentiality under chosen ciphertext attack (CCA). The reason is that the encryption scheme is assumed to be semantically secure, which means that given the ciphertext, an eavesdropper cannot determine any information about the plaintext.
Similar Questions
For each approach, state Secure or Insecure, and explain why that approach does or does not achieve the two desired notions of confidentiality described above.(e) Aldebaran computes cmsg = Enc(pkC, Enc(pkB, m)), cdest = Enc(pkC, pkB) and then broadcasts (pkC, cmsg, cdest). Chandra observes the broadcast containing her public key. She then computes c ′ msg = Dec(skC, cmsg), pkdest = Dec(skC, cdest), and broadcasts (pkdest, c′ msg). Lastly, Borealis observes a broadcast containing their public key, and obtains the message as m = Dec(skB, c′ msg)(d) Aldebaran computes cmsg = Enc(pkC, m), cdest = Enc(pkC, pkB) and broadcasts(pkC, cmsg, cdest). Chandra observes the broadcast containing her public key. She then computes m = Dec(skC, cmsg) and pkdest = Dec(skC, cdest). Lastly, she re-encrypts c ′ = Enc(pkdest, m) and broadcasts (pkdest, c′ ). Borealis identifies their public key in the broadcast and obtains the message m = Dec(skB, c′ ).
1. (15 marks) One of the approaches below is ”secure”. For each approach, state Secure or Insecure, and explain why that approach does or does not achieve the two desired notions of confidentiality described above.
Aldebaran computes cmsg = Enc(pkC, m), cdest = Enc(pkC, pkB) and broadcasts(pkC, cmsg, cdest). Chandra observes the broadcast containing her public key. She then decrypts the destination address as pkdest = Dec(skC, cdest) and broadcasts (pkdest, cmsg). Borealis then obtains the message as m = Dec(skB, cmsg).Is it secure?
(e) Aldebaran computes cmsg = Enc(pkC, Enc(pkB, m)), cdest = Enc(pkC, pkB) and then broadcasts (pkC, cmsg, cdest). Chandra observes the broadcast containing her public key. She then computes c ′ msg = Dec(skC, cmsg), pkdest = Dec(skC, cdest), and broadcasts (pkdest, c′ msg). Lastly, Borealis observes a broadcast containing their public key, and obtains the message as m = Dec(skB, c′ msg).
Which of the following best describes the concept of confidentiality in computer security?a.Ensuring that data is accurate, consistent, and reliableb.Ensuring that data is not modified or tampered with during transmissionc.Ensuring that data is not disclosed to unauthorized individuals or entitiesd.Ensuring that data is always available and accessible
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