People who code: we want your input. Take the Survey

# Questions tagged [chosen-plaintext-attack]

The attacker can specify his own plain text and encrypt or sign it.

252 questions
Filter by
Sorted by
Tagged with
163 views

### CPA Security vs Multiple Message Secrecy

In chapter 3 of Katz Textbook, there is a theorem which states as follows: "Any private key encryption scheme that is CPA-secure is also CPA-secure for multiple encryptions." I can make ...
50 views

### Private key encryption that is not CPA secure

I've been learning about different types of encryption schemes in class and I was wondering if it's possible to create a private-key encryption scheme that is multi-message secure but is NOT CPA-...
14 views

### LR Oracle for CPA Security for Multiple Encryption

How does LR Oracle model help achieve the CPA security for Multiple Encryption. I am not able to understand how LR oracle model gives an advantage over the normal encryption oracle.(Reference to ...
85 views

### Vulnerability in DES3 when key can be chosen

In the question there are two functions encrypt basically does IV ⨁ DES3(P⨁IV) and encrypt_flag just encrypts the flag after being padded into a multiple of 8. IV is a random 8 byte number which is ...
61 views

### Simple XOR cipher with pseudo random plain text of arbitrary length

We all know that simple repeated XOR cipher over plaintext is trivially vulnerable to known plaintext attack, even when just a part of plain text is known and even to ciphertext only attack if you ...
26 views

### Does IND-CPA to INC-CCA effects on the error probability?

If we have a key encapsulation mechanism (KEM) that is IND-CPA secure, with some error probability $P_e$ (probability that the shared keys are not equal). The goal is to use the Fujisaki-Okamoto ...
33 views

### Relationship among secrecy-constant, key space and message space

Here scheme $\Pi$ is $\epsilon$ - perfectly secret. Given that encryption scheme $\Pi$ = $(\mathrm{Gen}, \mathrm{Enc}, \mathrm{Dec})$ over $(\mathcal K,\mathcal M,\mathcal C)$ is called $\epsilon$ -...
317 views

27 views

### IND-CPA for permutation based encryption

My encryption function is some permutation using a permutation key. An input to the encryption function is encoding of my plain text where one plaintext is mapped to many encodings. Can we prove ...
223 views

### Security properties of ElGamal encryption variants

I'll use Taher ElGamal's A Public Key Cryptosystem and a Signature Scheme Based on Discrete Logarithms (July 1985 in IEEE Transactions on Information Theory, formerly in proceedings of Crypto 1984) as ...
281 views

### Is non-adaptive CPA strictly weaker than standard CPA security?

Today during a cryptography lecture an interesting question came up: Whether non-adaptive CPA security is equivalent to adaptive (FtG / LOR) CPA security. Now for a short description of what this ...
70 views

### Security of key bits under indistinguishability for randomized encryption

My question is about symmetric randomized encryption. Let c=E(k,m,r) be a randomized block encryption function where r denotes a random input chosen for each message block m. k and c denote the ...
66 views

### Is it possible to sample HE ciphertexts using pseudo-random generator?

I'm trying to sample HE ciphertexts which serve as ciphertexts encrypting some random values. I have realized a example program using Microsoft SEAL, which implements a variant of BFV scheme. ...
282 views

### How to prove that ECB mode is not CPA secure?

I am new to cryptography and I do not know how to prove the ECB mode is not chosen plaintext attack (CPA) secure.
933 views

### Does AES-ECB with random padding added to each block satisfy IND-CPA?

I present a modified version of AES-ECB. Suppose I want to encrypt the string hello, world. this is a test. For each block, I use the first eight bytes as my actual ...