Question

To demonstrate that the BadModPKC encryption scheme is not IND-CPA (indistinguishability under chosen-plaintext attack) secure, we need to show how an attacker can distinguish between two different ciphertexts generated from distinct plaintexts.

Answer 1

To show that BadModPKC is not IND-CPA secure, one must create a scenario where an attacker distinguishes between ciphertexts derived from different plaintexts, contradicting the indistinguishability criterion of a secure cryptographic system.

Step-by-step explanation:

To demonstrate that the BadModPKC encryption scheme is not IND-CPA secure, one must show that an attacker can distinguish two distinct ciphertexts that were generated from two distinct plaintexts. IND-CPA, or indistinguishability under a chosen-plaintext attack, is a property of a cryptographic system where an attacker, given the ciphertexts for two chosen plaintexts, cannot determine which ciphertext corresponds to which plaintext. In the context of BadModPKC, this would mean creating a scenario or algorithm where an adversary can use their ability to choose plaintexts and receive corresponding ciphertexts to gain some information that would allow them to distinguish between ciphertexts derived from different plaintexts, thereby breaking the scheme's security.