# All Questions

161 views

### Security of .net AES implementation and security of a hash MAC

My question rather splits into two sections: Is AES correctly and security implemented in the .net Framework? Are there any reviews of implementation mistakes that would weaken the security of AES ...
509 views

### RSA and One Time Password (OTP) service

What is the expert cryptographic opinion on the following? Assume that there is a web server and a client on web page. User on the Client calls an OTP web service on the server which: creates a RSA ...
616 views

### How compared encryption algorithm in terms of efficiency

I want to compare two cryptographic algorithms. The first algorithm is RSA, and second algorithm is ElGamal elliptic curve cryptography. Now, I’m looking for a way to compare the speed of the two ...
60 views

### Generating Polynomials for the MPQS

I'm going to try and eventually factor RSA-100, but my current QS needs a lot of improvement, so I'm going to try and switch over to the MPQS. I'm a bit confused as to how the MPQS works, which is ...
209 views

### Differential Cryptanalysis of FEAL-4

I'm currently carrying out a differential attack on the FEAL-4 algorithm, however I have hit a bit of a wall. Basically I attacked the final round first ($K3$) using the differential characteristic ...
135 views

### Quadratic Sieve Bottleneck, Multiple Polynomials an option?

After my failed attempt at trying to implement the ECM, I started working on the quadratic sieve. It works, but the bottleneck is finding smooth values over the factor base. The way I implemented it ...
164 views

### Timestamping services authorities, utilizing Linked, hybrid and other than PKI schemes

What are well respected Cryptographic Timestamping authorities utilizing more sophisticated than just PKI (RFC 3161) schemes, like Linked, Linked and signed, distributed hash trees (maybe P2P?), ...
249 views

### Is TOTP or a timestamp encryption a better timestamp-based authentication token system?

Are there advantages to using TOTP over encrypting a timestamp with a shared secret, in cases where the readability or ease of typing the token are not important?
227 views

### Proper formatting of symmetric algorithm secret key

Given this description from RFC 4880 sec 5.1: The value "m" in the above formulas is derived from the session key as follows. First, the session key is prefixed with a one-octet algorithm ...
232 views

### Most frequently used digital signature schemes in the recent years

I am looking to understand if there are any hard figures on which digital signature schemes are most commonly in use today. I'm only really interested in what is employed recently (ie. last couple ...
20 views

### 128 Bit AES Issue

I'm trying to use the 128bit TI_aes implementation on my 16bit microcontroller and I'm having the weirdest issue. Every input where two bytes within a word are identical is successfully encrypting ...
8 views

### How to construct Hash function of type H:{0,1} * X G -> Zp*?

In many cryptographic protocols design, I have seen the statement 'Choose a Hash function H1:{0,1}* X G -> Zp*' i.e a hash function which takes as input a binary string of finite length and a random ...
15 views

### Do most TLS 1.2 implementations express curves in a canonical form when performing EC arithmetic?

Sorry if this is a silly question, but does anyone know if the cryptographic libraries which implement TLS 1.2 for Firefox, Chrome, etc. express a given curve in a canonical form (i.e. one of ...
19 views

### Questions about a SHA3 cipher stream encryption scheme

I've written an encryption implementation using a hash as a cipherstream FOR DEMONSTRATION PURPOSES. I know it is slower than more sensible options such as AES but I'm interested in several things, ...
11 views

### How are the attributes of a user authenticated in attribute-based encryption?

It seems that the papers I am reading do not talk much about this point. That is how the attributes of a user are authenticated in ABE system. To my understanding, there is an attribute authority ...
30 views

### Caculated time One Point Multiplication with double and method

I am using double and add method for point multiplication in affine coordinates. How we compute 1PM in double and method? Di Wang said one point multiplication consists of repeated addition and ...
22 views

### Gaussian distribution in lattices

In many lattice based cryptosystems, Gaussian distribution is used. Can you explain why only Gaussian distribution is preferred?
29 views

### Fast hash for 64-bit inputs

I am looking for a fast hash (~few machine instructions) to be used for hash tables with 64-bit keys. I can't use SipHash as the hash function will be inlined in too many places and so the code size ...
21 views

### Dieharder text file for output of AES_CTR

I want to run Dieharder test suite on the output of AES_CTR. How should I form the text file consisting of the cipher text obtained from AES_CTR, to be run directly with Dieharder package for linux?
20 views

### why OCB over AES for authentication encryption?

why should anyone use OCB-offset code book over AES algorithm?
24 views

### Have ciphertext and key but need to figure out encryption method

So I have a block cipher (I think) that I need to break. I have the ciphertext and the key, but not the method of encryption, and was wondering if anyone could help me figure that out? The key is a 9 ...
29 views

### AES Twofish Serpent

AES-Twofish-Serpent how to create this combo encryption? I am using Linux Mint and i want to encrypt few big folders in one folder, but to be hiden.
32 views

### What are the pre-requisites I need to be able to code Salsa20 in C#?

I've taken a basic course in Cryptography and we've learnt various algorithms and their usage. I've implemented RC4 and Triple DES in C# with ASP.NET. For a project that I am a part of, I need to ...
10 views

### How do you apply bilinear mapping to attribute based encryption?

I'm new to both bilinear mapping and ABE. I have a vague idea of how bilinear mapping works now, but I don't understand how it applies to ABE. Can someone give me an example?
25 views

### Permuted Hash Table

Suppose we have a hash table, $HT$, consisting of $100$ bins.The hash table uses a hash function $H$ that is public. We all know that given value $a$ we can compute the address in the hash by ...
26 views

### Interesting Topics for Projects?

I hope this is not a off-topic question for the site, but I was wondering if I could get any recommendations for project topics in cryptography suitable for someone just learning basic material now. ...
25 views

### How to create Crypto based Project

I took Cryptography course last semester and It was very interesting. To have a more practical understanding, I thought I should create a mini project. Below is the ...
23 views

### Poly1305 vs VMAC: is VMAC much better for long messages?

VMAC seems to me much more secure than Poly1305 on long messages (the security of the latter decreases linearly with increasing message length). Is this of practical relevance?
22 views

### Miller Algorithm of Weil Pairing implementation for Python2

I would like to implement miller algorithm for Python, but it cannot work correctly, Please help me. (1) Please tell me Miller algorithm's output of the following case. ...
23 views

### SET Protocol (SET)

I would like to know if the current SET protocol uses 3DES or AES other than DES and RSA? I have look into many articles but some of them were outdated.
37 views

### implementation of authenticated encryption algorithms on GPU

I am trying to implement an authenticated encryption algorithm on GPU. i have selected an algorithm that can be parallel both in Enc and Dec. this new authenticated encryption algorithm has a small ...
10 views

### A standard for multi-key provider encrypted data?

I'm looking for a standard that standardizes data encryption with multiple and diverse key sources to represent a heterogene access structure and culture. The standard must offer the following ...
38 views

### When we use permutation and random long sting to hide a message

This question is modified version of this: Can we use merely permutation to hide a message? I have an English name $m=m_1 || m_2 ||..||m_{30}$. I pick a random string $d=d_1 ||..||d_{70}$ I mix ...
28 views

### Subset sum hardness

Hardness of a subset sum probleme depends on it's density. Is it possible for a subset sum problem to be intractable even if it's density is less than 0.9408 ?
23 views

### Degrade in performance with SSL_OP_SINGLE_ECDH_USE?

We have used SSL_OP_SINGLE_ECDH_USE when setting up our SSL_CTX . This seems to be causing a degrade in performance. I'm not able to find proper documentation for it except that it generates new ...
31 views

### Show that the shift, substitution, and Vigenere ciphers are all trivial to break using a known-plaintext attack

i think that we can use the notion of knwn plan text that we could have pairs of both cipher and plantext msg and try to find way from one to another to recover the key i dont knw how to make it with ...
53 views

### history of non secret cryptograph

Prior to the discovery of any specific public-key schemes, such as RSA, an existence proof was developed whose purpose was to demonstrate that public-key encryption is possible in theory. Consider ...
23 views

### Implementing cryptosystems with various programming langauges

I know that most cryptosystems are currently implemented in C/C++. Has there been any effort to implement cryptosystems in programming languages such as Agda where proofs can be written about ...
31 views

### Solving ADFGVX decoding with only ciphertext

Hi I'm new to the world of crypto and I'm trying to decode a message. I know it is encrypted using the ADFGVX cipher. I also have a ciphertext, but I have no other information given to me. My question ...
33 views

### Symmetric encryption vulnerable when encrypting and decrypting are the same?

To my understanding, symmetric encryption is where encrypting and decrypting data can occur with the same key. It's possible for symmetric encryption that the encrypting and decrypting algorithms are ...
36 views

### Strength of TripleDES (DESede) in Java (Sun JCE)?

I'm introducing Jasypt to a spring-boot project. The default algorithm for storing passwords with it is PBEWithMD5AndDES. Since I've got some reservations on using that cipher, I'm looking into ...
30 views

### How to calculate unicity distance of Fleissner grille?

I need to calculate unicity distance of Fleissners grille of $M \times M$ size. All I know is that plaint text redundancy equals $2$. The alphabet is not specified. Is it possible to calculate its ...
64 views

### splitting the plaintext and ciphertext into blocks

Say I was to use RSA with a given value of n. I choose to split the plaintext and ciphertext written in a 27 letter alphabet into blocks with k and m characters resp. How would I find the largest ...
19 views

### Uniformly distributed sub-sequences of a main PRG sequence

Let $g_s$ be a pseudo-random generator that generates uniform distributions of numbers ($s$ : seed) of a fixed bit-size. One wants to compare the pseudo-randomness of certain subsets of elements ...
54 views

### Semaev summation polynomials

I am little confused how this attack works. We have the points $P, Q$ such that $Q = nP$. We let $u_{1}$and $u_{2}$ such that $R(x,y)=u_{1}P+u_{2}Q$. Then if we find the solution $x_1,...,x_n$ of the ...
74 views

### Proof that this is not a secure pseudorandom function

$p$ is a large prime number. Consider the following function $F:\mathbb Z^*_p \times \mathbb D\rightarrow\mathbb Z^*_p$ where $\mathbb D=2,....,p-1$. $F_k(x)=x^k \bmod p$ Proof that it's ...
20 views

### Using Montgomery ladder to calculate the coordintes

In one of my assignments I need to solve the below: For a Montgomery curve $3v^2 = u^3+u^2+u$ over ${\mathbb{F}}_{11}$ and point $P = (9,8)$. I need to compute $x$ coordinate of $3P$ using ...
41 views

### Proving pseudorandom generators

Can anyone please help me on how to prove or disprove (by counterexample) whether the following function $G'$ is a PRG (Pseudorandom Generator) given that $G$ is a PRG. G'(s) = ...
Currently reading Krawczyk's HMQV paper https://eprint.iacr.org/2005/176 and trying to follow what he says about the group respetnation attack on MQV: It says that for any group of prime order $q$, ...