# All Questions

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25 views

### Faster Shuffling for a Simple Application

Alice, Bob, and Charlie are working on three projects. Alice is the manager. At the beginning of each day, she chooses one project to work on (this choice is based on her preferences and is not ...
75 views

### Create a ciphertext that decrypt to different plaintexts with different keys in RSA

(This is inspired by this question 1; have also read this question 2 but it's one-time pad) I would like to know, given two message $m_1$ and $m_2$, as well as public keys $(e,n_1)$ and $(e,n_2)$, ...
24 views

### Difference of Hash function and Cryptographic Accumulator

What's the difference between a one-way hash function and a cryptographic accumulator? Somebody can explain it in simple way?
34 views

### A Mechanism for An Endless One Time Pad: Vulnerabilities? [closed]

One time pads have the disadvantage of running out and renewal can lead to discovery. What are the vulnerabilities of this proposed mechanism: A single one time pad of random numbers is used. The ...
16 views

### How to design a moderated, group for private messages?

I’m trying to figure out how I could create a private group that was P2P yet still allowed someone to moderate members (no public access to messages). I’m assuming standard hybrid encryption (RSA/EC + ...
18 views

### PQC schemes & theory on academic courses

This question doesn't cover any technical aspects of PQC but I would want to know if undergraduate computer scientists study at a good level any of the available PQC schemes in literature during their ...
34 views

### RSA signing - does EMSA-PKCS1-v1_5 padding need to be verified?

I am working with an embedded system that accepts firmware updates only if they are validly signed by a particular 2048-bit RSA private key (the embedded system's bootloader knows the corresponding ...
20 views

### Help with next step in the Quadratic Sieve

So I am at the same step as someone from math.stackexchange but he never recieved an answer so I will copy-paste his question here: Say, for N = 90283, I compute bound 𝐵=𝑒(12+𝑜(1))(ln(𝑛)ln(ln𝑛√))...
27 views

### Message space when using the group of QR's for El Gamal Encryption

My textbook states, that the DDH-assumption is not satisfied when we use the group $\mathbb{Z}/p \mathbb{Z}$ and demonstrates an attack using Eulers Criterion. After that, it states that one should ...
26 views

### Generate keys with Edwards25519 - Equivalence to Curve25519

I am trying to generate Ed25519 keys based on a 32-byte seed. According to RFC 8032, in order to create the public key, you have to take the private key, hash it with SHA-512, prune it, and then use ...
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So I downloaded the Breach Compilation (the 1.4 billion usernames w/ respective passwords). When doing so, the friendly dev-like homies they are over @ github where the .torrent file for the latter is ...
52 views

### How to convert a Diffie–Hellman key exchange number to work with different encryption algorithms

I just read about Diffie–Hellman key exchange and was wondering how the value created from that can be used for any encryption method. Here is a link of where I read it from.
42 views

### Composition of X25519+XSalsa20+Poly1305

In an correct implementation of X25519+XSalsa20+Poly1305, I think I have the right understanding in saying that the Poly1305 message authentication code is a ...
32 views

### How challenge response password recovery mechanism works with disk encryption? [migrated]

For the sole purpose of learning, I am trying to figure out how disk encryption software is able to recover password of an encrypted disk using a challenge response mechanism. Th recovery process ...
20 views

### complexity of ElGamal ECC and Menezes-Vanstone ECC? [closed]

How to compute the complexity of ElGamal ECC and Menezes-Vanstone ECC?
50 views

### State of the Twofish encryption cipher - is it broken? [closed]

Twofish was one of the finalists in the last cipher competition together with Serpent and AES, where AES won. Do you know of any cryptanalysis on Twofish and if its considered "broken" or still ...
22 views

### Question regarding round count of setup/signing phase for t-of-n threshold signature scheme

I am currently investigating threshold (EC)DSA signature scheme. In many schemes, there are two phases -- setup phase where necessary computation for random value generation and secret sharing setup ...
78 views

### Given generator $g$ with prime order $k$ in $\bmod P$. Does increasing $P = 2 \cdot c \cdot k +1$ decrease security? Increasing $g$ increase security?

An adversary wants to find $a$ in $$m \equiv g^a \bmod P$$ He knows prime $P = 2 \cdot c \cdot k +1$ with it's primes $c,k$, value $m$ and $g$. And he also knows that $g$ only has an order of $k$, ...
7k views

### How hard is it to guess a 8 digit PIN?

Say that there are different live situations where you have to select own PIN numbers. Can someone say if it is possible to guess a 8 digit pin within 3 tries, given any methods or resources? Is ...
43 views

### Fully Homomorphic Encryption - state of the art

What are the latest advances in fully homomorphic encryption? First of all, I am interested in cryptosystems based on LWE / RLWE and NTRU problems.
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### Do I need to encrypt the IV?

For example, I'm using AES-CTR. I use fixed (random generated) key and random IV. I know that I have to encrypt key but I don't know about IV. If I will encrypt 1 block of data with fixed key and ...
19 views

For the AES-GCM mode within many cryptomodules, their FIPS-validation certificates list the options: Payload Length: 504, 512, 1016, 1024 AAD Length: 0, 504, 512, 1016, 1024 For example in OpenSSL, "...
22 views

### Differential cryptanalysis for DES reduced to Four Rounds and about S/N

I'm reading the paper "Differential Cryptanalysis of the Data Encryption Standard(2009)" and I was stuck in a certain part while reading it. In chapter 4, they explained about differential ...
47 views

### What is the formula to calculate password entropy? [closed]

I saw in another thread: Is using 7-8 random words from all words of a language as password a good idea? These calculations: If we assume that English has 171,476 words. Then with 8 words the ...
12 views

### ElGamal ECC. and Menezes-vanstone ECC

Can anyone tell me how to measure the security force of ElGamal ECC. and Menezes-vanstone ECC.?
32 views

### How to know if an ElGamal ciphertext is well-formed?

Is there a way to prove/verify that an exponential ElGamal ciphertext of a message representative $\widetilde{m}=mG$ is well-formed, meaning that $r_1 = r_2$ in: C = (R, S) = (r_1G, \widetilde m + ...
22 views

### Bilinear pairings with groups of safe prime order

I am looking for a curve with a bilinear pairing of safe prime order. I.e. a bilinear map $G \times G \rightarrow G_T$ where $|G| = p$, $p = 2q +1$, and $p,q$ are both prime. Is it feasible to find ...
49 views

### Checking if point is on EC twist

Given a short Weierstrass elliptic curve $C$ over $F_p$ and a point $(x, y)$, it is easy to verify that $(x, y)$ either satisfies the curve equation (on-curve) or does not (off-curve). In the case ...
115 views

### How safe is my method

I'm building a website. I have an API which takes 2 parameters: delete_user(user_id, hash). And there is method to evaluate hash using SHA512: ...
33 views

### I know my passphrase. I don't remember specifically how I entered it

First if this is the wrong place to post this please forgive me. I know my passphrase. I don't remember specifically how I entered it. ex. If the phrase is "The house at the end is blue and white. I ...
19 views

### What is the best way to encrypt whole partitions with Ed448-Goldilocks?

I like crypto, but I'm a bioanalytical chemistry person by trade. I like this algorithm and was wondering if I could use it to encrypt partitions like a MBR that prompts a passphrase, like BitLocker.
25 views

### Is there a program i can use to find a hidden message in a BMP file?

I am working on a puzzle and think there is a message hidden in one of the files that is a BMP file. I am wondering if there is a program somewhere that could find it?
82 views

### Is there a library that implements the “Mickey Mouse Version” of asymmetric cryptography?

Here is what I mean with "Mickey Mouse Version": CHARLIE makes a keypair key1 and key2 ...
6 views

### Why CryptDecrypt returns NTE_BAD_DATA? [migrated]

I want to create implementation of AES-CBC. I have created this code: encryption process: ...
30 views

### Retrieving ElGamal message with negative exponent value

Although the ElGamal scheme states that the message $M$ must be $1 \le M \le p-1$ in this paper: A Secure and Optimally Efficient Multi-Authority Election Scheme they propose a method where the ...
22 views

### NIST Approved Entropy Source List

Per NIST SP 800-90B – Section 3 – Entropy Source Validation : This Recommendation provides requirements for validating an entropy source at a stated entropy rate. Validation consists of testing by an ...
24 views

### Asymmetric non-interactive proof of work scheme

I'm looking for a non-interactive proof of work scheme. I want for it to (1) be faster to find solutions to if you're in the possession of an arbitrary secret, like a private key, and (2) for the ...
94 views

### 2Des is double secure of DES?

I read this question in my book (that doesn't have a response). 2DES is doubly more secure than DES? I know that 2DES can be attacked from meet in the middle ...
27 views

### AES key with DES3_CBC_PAD mechainsm

I am new to cryptography and have a question. If I try to wrap some key using an AES key using DES3_CBC_PAD as a wrapping mechanism will this go to work? I am doing this operation inside an HSM.
10 views

### Scrypt cipher - known vulnerabilities and cryptanalysis? [duplicate]

there is a Scrypt cipher which is used for exmaple by some cryptos like LItecoin for their mining algorithm. I never heared of scrypt. I know eg SHA256 which is well analyzed and considered as secure ...
72 views

### Scrypt KDF cipher (scrypt CLI) - known vulnerabilities and cryptanalysis?

There is a scrypt cipher that is used for example by some cryptos like LItecoin for their mining algorithm. I never heard of scrypt. I know eg SHA-256 which is well analyzed and considered as secure ...
67 views

### Good pre-image resistance value for hash visualization

I want to do "hash visualization", i.e. derive a human-meaningful information from a hash, like a phrase or an avatar. But the current techniques usually don't use many bits, for example tripphrases ...
25 views

### Statistically Binding Commitments

Is it possible to ever have a commitment scheme that is statistically binding but not perfectly binding? The sender would be computationally unbounded, hence could always computationally trudge ...
31 views

### Is encrypting data with AES-CTR-128 and keys with RSA-2048 secure?

Here's a question. I have a file that have to be encrypted with strong cipher (I've choosen AES-CTR-128). I'm using MVC 2019 to compile C++ program. Firstly, I create RSA-2048 key pair (public and ...
24 views

### Would these Vigenere cipher use cases be considered secure? [closed]

I've a couple of questions about my knowledge of the modern and secure use cases of vigenere. I'd like to know whether or not they'd be considered secure by todays standards - By that I mean easily ...
21 views

### NIST test suite for random numbers [closed]

I am using sts-2.1.2 (NIST test suite for random numbers) in Ubuntu 16.04 for testing random numbers and I've installed it successfully. However I don't know how to perform test on random numbers, how ...
27 views

### Difference between Verification and Public Key for Signature Schemes

This is a semantics Question. Typically, in many asymmetric schemes, for this question specifically, digital signatures, we see that designers describe the key given to the verifier as Public Key. ...
31 views

### Question on PKCS11 2.40 spec and AES_CBC wrap

PKCS11 cryptoki version 2.40 Current mechanism specification (section 2.8.5), says below statement for AES CBC wrap: For wrapping, the mechanism encrypts the value of the CKA_VALUE attribute of the ...