In choosing a padding method we need to address two aspects...

In choosing a padding method, we need to address two aspects: Question 7Select one: a. satisfying the privacy property and minimizing padding cost. b. Minimize security cost and meet the expectations of privacy and propriety method c. Both A and B d. None of the Above

Transcript

00:01 Hello, students, we need to prove here that any cps -secure encryption remain cpa -secure when augmented by padding input, right? so basically, we need to prove that any cps -secure encryption will remain cpa -secure when we increase the padding input numbers in that or any encrypting bits or digits, right? so first we need to explain then what is encryption.

00:35 So basically encryption is the process of protecting data.

00:41 So if we write about encryption, encryption, so basically encryption are the technique and methods to protect data by using mathematical algorithms right.

01:04 So that no intruder can see what is the added data we need to hide that data right so if i write about what is cpa secure encryption right so if i write about cp secure encryption a chosen plain text attack which is often called it cpa chosen plain test act is a crypto analysis is a crypto analysis attack model that assumes the attacker can acquire can acquire the cipher text for any plain text right the purpose if i talk about the what is the purpose for doing that the purpose of assault the purpose of assault is to obtain information that compromises the encryption that compromises the encryption that compromises the encryption scheme security right so basically this is the whole goal of attack to reduce that in to break that encryption and take data right so we need cpa encryption.

03:42 So in the question we are asked that we have to prove cpa secure encryption remain cp secure right it will remain when augmented by padding the input when we augment this encryption by padding the input right so we need to prove.

04:00 So first we need to understand padding inputs and what is padding right so we will do it so padding just refers to an approach to encode arbitrary length data into data that is a multiple of block length right the only requirement is if i write the only requirement is that this encoding is reversible right more formally a padding scheme more formally if i say a padding scheme should consist of two algos should consist of two algorithms.

05:04 So if i write here, first we take as a pad.

05:09 So in a pad, we take input as a string of any length and output a string whose length is multiple of the block length, right? so i will explain this by example.

05:21 And if i talk about what is unpaired? so this is the center side, right? this is the center side, sender side.

05:31 We pad and we take input a string of any length, output a string, output a string whose length is a multiple of a block length, right? and what is the unpad? unpad is receiver side, receiver side, right? so the inverse of pad, right? the inverse of pad...

Question

In choosing a padding method, we need to address two aspects: Question 7Select one: a. satisfying the privacy property and minimizing padding cost. b. Minimize security cost and meet the expectations of privacy and propriety method c. Both A and B d. None of the Above

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