All Questions

I understand the TLS cipher suites using CBC mode are susceptible to timing attacks. From that understanding it seems that the cipher suites using GCM (CTR-based) are safe to use considering they don'...

I've recently started looking at HMAC, and there a few things that I'm not 100% sure that I'm understanding correctly. Am I right about these three things? HMAC-SHA-xxx has an output length of xxx ...

In TLS 1.2 when using ECDHE_RSA, the ServerKeyExchange message contains a signature over the server's ECDHE public parameters. My question is: Is the signature over ...

Just looking for a bit of an explanation on the concept of hybrid symmetric and asymmetric encryption. My understanding: Client requests public key from https://site1.com The client receives the ...

My Question is based on poncho's answer in this post. If you're doing a meet-in-the-middle attack against 2DES with only on a plaintext-ciphertext pair $(P,C)$, I understand that the expected amount ...

In McSherry and Talwar's paper which introduces the exponential mechanism for differential privacy, they say that the Laplace mechanism can be captured by choosing the score function as $q(d,r) = - |f(...

What is the benefits of quantum computing vs parallel processing using classical computer ? Can classical parallel processors outperform quantum computing ?

In the exponential mechanism in differential privacy, we have a set of inputs $D$ and a set of outputs $R$. We assume that we have a score function $q\colon D \times R \to \mathbb{R}$ and a measure $\...

I am working on this problem where the set up is like this: There are three hosts: A, B and C. A wants to send a message to C which passes through B. At A the message is hashed, the hash is padded to ...

I am new to Computer Security and I am trying to solve the following exercise: Consider the following encryption function which transmits one letter. Let n be a fixed positive integer. The ...

i want to test my login page but i used password encryption before password was saved in the database. if i try to enter from login page will display error message "Incorrect password or email". and ...

Let $\mathbb{F}_2^n$ be an $n$-dimensional vector space over the field $\mathbb{F}_2 = \{0, 1\}$. Assume that I have 2 sets $A, B \subseteq \mathbb{F}_2^n$ which have the following property: there ...

While reading the SIDH key exchange protocol, I noticed that all the isogeny computations and curves are defined over the extended prime field $\mathbb{F}_{p^2}$. Does it make the problem ...

There are some protocols, e.g. this, that require parties to compute/use RSA modulus: $N$ without knowing it's factors or $\phi(N)$. One way of doing it is to use a trusted party. Question: Is ...

I'm reading this article on the basics of cryptography and it says that the main principle is about taking such an algorithm that knowing the end result and the algorithm, an eavesdropper wouldn't be ...

Is there any encryption software (full disc encryption or container mode) available for Windows 98? Same question for plain DOS 6.22. Maybe it's strange, but for some reasons I need software like that....

Post Structure: Sources Cited Question & Details Before You Answer Useful Info From Comments Sources Cited: https://blog.cryptographyengineering.com/2012/05/19/how-to-choose-authenticated-...

This apparently was a bug with WhatsApp a while ago. I am endeavoring to recreate it and understand it. The bug had to do with the fact that the same key was used to encrypt plaintext on both the ...

I'm trying to optimize the decryption process for Paillier Homomorphic Encryption (PHE) using the Chinese Remainder Theorem (CRT). However, I want to check if there's a different way of applying CRT ...

By Euler's theorem, if $\gcd(e,n) = 1$, then $e^{\varphi(n)} \equiv 1 \pmod n$. But why does RSA need to make sure that $\gcd(e,\varphi(n)) = 1$?

Problem: I'm trying to figure out how to solve this, apparently it's hashing the hash value itself. So G has two rounds of hashing the original message x. I tried searching for the relationship ...

Does this look like encrypted output, please? { 811 #2D #CC29 #C102 #E9 #B5 #C62 E01 #C8 #2139 #68F1 #08 #A6 #672 241 #8C #0E29 #8642 #86 #C6 #262 E61 #4B #0E29 #A942 #...

I'm using openSSL aes_cbc128 to encrypt/decrypt some text coded in C++. When I run with only numeric data, everything is fine. When I run with alphanumberic data, the last block does not decrypt to ...

As I understand, the Content Scramble System (CSS) uses proprietary 40-bit stream cipher algorithm to decrypt the DVD content My question is; where does this key come from? is it embedded within the ...

Can someone explain me in basic simplistic english if possible how does McEliece asymmetric encryption works and why its quantum safe ? Thanks in advance.

I am looking for a cryptographic hash function that I can configure for HMAC. The input that I will hash is around 50 bytes. The function must be fast, and computationally lightweight.

I read SHA1 is still a secured hashing function with no collision found as of now. However, it's just a matter of time for someone to come up with such a collision or attack. Therefore, in new ...

Some Protocols require one party to send $n$ random challenges (or random values) to another party. For communication efficiency purpose, one can pick a random key for a pseudorandom function, and ...

The Web Crypto API available in most browsers supports both AES-GCM and AES-KW for key wrapping. There are examples for AES-KW and AES-GCM performing key wrapping, and a popular live table indicates ...

I am researching possible implementations of IEEE P1363-3 Identity-based Cryptography schemes (https://books.google.gr/books/about/IEEE_P1363_3_D9_May_2013.html?id=IADLnQAACAAJ&redir_esc=y ) and ...

I have the following requirement: There are N public/private RSA key pairs. The encrypted data must be decryptable by any of the private keys alone, but not by any other key. For encryption, the ...

I have designed a protocol where one entity acts as a "client", sends information to one of many "server-parties". This second party sends some other information to another "server-party" and so on, ...

How should I provide counter value in order to test my algorithm with the standard test vectors given in IETF Tools? Code snippet: ...

Post Structure: Prior source material studied Question & Details Assumed threat model Example Assumptions Clarifications Prior source material studied 0.1. RFC 2898 0.2. HAC (Handbook of ...

Let say we want to break aes-256 using a quantum computer, that would take 2^128 operations using groove algorithm. Now let say we have a 128 qubit quantum computer, can this be broken instantly ? If ...

I am reading about Yao's and GMW protocols and was wondering if there is any perfectly secure MPC protocol in the semi-honest setting, where the underlying circuit is a Boolean circuit (eg. n=3 and t=...

Given the block-ciphers defined as follows : $1.$ $C=$ $E_{k1}($$E_{k2}$$(M))$ $2.$ $C=$ $E_{k1{\oplus}k2}$$(M)$ $3.$ $C=$ $(E_{k1}(r),E_{k2}(r$ ${\oplus}$ $M))$ where $C$ is the cipher ...

I've got a cipher I believe to be polyalphabetic, which may or may not have a key in which I've discovered some patterns, and I'd like to know how I can use these patterns to try to understand how the ...

I have been reading Fast Secure Two-Party ECDSA Signing by Lindell, and I see that in key generating and signing (pages 9-10, especially visible from Figure 1), only the first party performs a ...

I'm currently reverse engineering a binary that uses Blowfish. A sample input would be: 08 00 01 00 1C FB 19 00 When this data is encrypted and then decrypted, I ...

I know that there are many encryption standards that take a key and sometimes an IV, and produces a cipher-text (the most prominent one is AES). These standards usually involve many rounds of addition ...

Is SHA256 MAC (or HMAC) vulnerable to any quantum attacks? Game setup: The attacker's goal is to produce a valid MAC to be accepted by other devices in the ecosystem. The ecosystem consists of ...

A naive approach to compute a multiplication $a \cdot b$ in a Galois field of the form $GF(2^n)$ is the russian peasant algorithm. However, it does not run in constant time and therefore is not safe ...

I am aware that this is at the border to security but I guess that I will rather find an answer here. The question is which institution generally assigns object identifiers for cryptographic ...

The setup is shortly this: There are two custom switches (think of an FPGA for example), both are handling 10-100 Gb/s orders of traffic from their outside facing interfaces. This is normal traffic. ...

I'm trying to understand the structure of a OpenPGP message in detail. Therefore I generated a test message and parsed it using gpg --list-packets. The output is ...

As I have read the latest state of art in group key agreement is the Asyncronous Rachet Tree. But in applications like IRC that exists high user movability (users join in ans leave the room). Is ...

Quote: Most of these answers are a bit misguided and demonstrate a confusion between salts and cryptographic keys. The purpose of including salts is to modify the function used to hash each user's ...

The receiver R chooses $a,b,r$ and computes as follows: If σ = 0 then $A = (g^a, g^b, g^{ab},g^r)$. If σ = 1 then $A = (g^a, g^b, g^r, g^{ab})$. R sends $A$ to S. Denote $(x,y,z_0,z_1)$ the tuple ...

So this is an age-old example of why encrypting images with ECB is a terrible idea, since the underlying pattern of the image remains the same. Referenced from: If you encrypt an image (AES), is it ...