All Questions

I'm taking an intro course to cryptology, and we have an assignment challenging us to break the Geheimschreiber, or G-Schreiber, using a known plaintext attack. The plaintext is the Latin alphabet ...

i was wondering if there's any option to create sort of a time capsule in a word Document, meaning not encrypted by password rather than a date- let's say i send the document today but the receiving ...

I don't have much formal background but I could not find a suitable explanation for this after searching on Google/Wikipedia. What is the meaning of the term language as used in cryptographic ...

I've got a task to provide the integrity and an authenticated encryption for files in our application. I need an assurance if my way of thinking is correct. I can't use AES GCM, I have to stay with ...

Assuming you only modify the key schedule so that each of a 128-bit key is used at least once, would DES be about as secure as other ciphers such as AES? I am not talking about 2DES/3DES or other ...

Hy community, I have read some documents to decrypt ciphertext without key using Frequency analysis. here are my questions : If the most occurring Char is not 'E' then how do we start? Let's say I ...

Assume we use batching and modulus switching techniques to reduce the size of ciphertext in fully homomorphic encryption (FHE). Question: What is the shortest ciphertext bit-size output by the most ...

In this Wikipedia article about Neural cryptography (section applications) it states: In 1995, Sebastien Dourlens applied neural networks to cryptanalyze DES by allowing the networks to learn how ...

I know the distance of dual of reed solomon codes is n-k+1 beacuase it is MDS code. Now us consider the following linear block code \begin{equation} C:\mathbb{F}^{k}\rightarrow \mathbb{F}^{n}\\ (c_0,...

Assume we have two computing parties for SPDZ protocol. The two parties are also the input parties. How can they share the MACs on their input shares assuming one party is the master who owns the MAC ...

Many resources talk about the benefit of Proxy Re-encryption (PRE) and I also implement my PRE using Elliptic Curve key pair. But after I set up Global parameters, I can encrypt very small data maybe ...

You ae given the following phrase "Stop Now" and you have a 100x100 pixel image where each pixel is represented as an 8 bit gray-scale quantity. With these pixels below, show as much as you can hide ...

We know that the output bias of a randomness extractor is $ \epsilon = 2^{-(sn-k)/2} $ from What is the relationship between entropy conditioning and final output bias in a TRNG?. The following is a ...

Given a public key for RSA, I have extracted the modulus which looks like this : ...

I'm trying to implement the scrypt key derivation function using JavaScript. When implementing the algorithm, I found that there was a function called SHA1_Compress listed in the specification. Is the ...

This question concerns the Signal protocol's X3DH key agreement protocol as documented here. Obviously, if Alice and Bob have never contacted each other before, they need to run X3DH at least once to ...

Lets say we have an arbitrary but dictionary attackable password that is less than 256bit. (Lets just say the password is '1234Password'). We encrypt this password with a securely random 256bit key ...

So I am little confused about a type of encryption I read about. You can encrypt your E-mails and pretty much all kind of information using PGP key pairs. However, I am confused if an encrypted ...

Please kindly help me, I would like to compute hash value on cipher text.

Having: plaintext $P$ a hash function $H$, encryption $E$ with key $k$ $h_p = H(P)$ and $h_{E_P} = H(E_k(P))$ Is there an encryption scheme $E$ or hash algorithm $H$ that allows proving that $h_{...

I need to generate 64bit data sequences for 16 times pseudo randomly. How many bits should the linear feedback shift register have to be able to do so? I mean what is the number of bits for the ...

xrqsx ibkfy lawcc jrohm ouyyl mrqgi ucscc ahakc zwuhg axroc bipwe zatqd eqrmh zgtmv ygoyq qlmqd kbpyd dqqcj glhka pbkae clxru cuhbg wtetx riymt ezdyd dhksj opgia piwzw fmzwa egpgi jpqxn oaady

The scenario: On the one side a user enters a pass phrase to encrypt a stream of data (AES-GCM) and a symmetric encryption key is derived from the pass phrase using plain SHA-256 (so not a slow ...

I'm trying to find the logic for introducing the S-box, but having trouble understanding why. In a simple cipher, e.g. c = pt xor key I understand that I can ...

In RSA, for calculating $d$, we have the $\lambda(n), e$ and we calculate $d$ such that $e d \equiv 1 \pmod{\lambda(n)}$. As per the Wikipedia example is given for RSA - the value of $e$ is 17, $\...

Background Cryptography can be said to provide the tools used to fulfill the goals of information security. The three pillars of information security are confidentiality, integrity, and ...

Given: Known ciphertext (in hex) (ciphertext is the exact length of the message (i.e. non-padded). It is known that the cipher was developed using CBC. There is one and only one ciphertext message ...

I think I know how rainbow table works , I just wanted to make basic reduction function(for md5) in python with an approach that I am not taking a certain portion of hash but am taking the full hash ...

I have the following use case: Alice owns the domain alice.com and Bob owns bob.com. I want to users to create a hash for ...

GOST cipher , Hight cipher and SEA cipher use key addition based on modular arithmetic addition (module key size $\boxplus$) compared to many ciphers which use arithmetic addition modulo 2 ( $\oplus$)....

I am working on an Cryptographic exercice but I'm not quite sure where to start. We suppose a prime generation consisting over a loop to take a random integer n and pass its number to a 5 round ...

I want to explain RSA to a programming audience with no cryptography background and I want to be sure my explanation is correct. The goal is to help them understand how RSA works under the hood. You ...

Consider the NMAC construction: This is a proposed exercise in my notes: Assume F is a PRP with $n = l(n)$. Is it secure to replace $k_0$ by $F_{0^n}(k_0)$ and $k_i$ by $F_{0^n}(k_i)$? In ...

The company I work for provides a software solution. The software is licensed and I have access to the license generator (which, BTW rules me out as a cracker - I don't need to crack the license, I ...

I'm trying to build a encrypted database where we cant trust on the database manager. And since encrypt data in a deterministic way is bad, attackers can recover information doing frequency attacks, I ...

I have generator based on sampled noise (reverse-biased transistor - actually ChaosKey but that's not that important). The noise source is fed into ADC and sampled with 16bit resolution (2 bytes). ...

I have understood the proof that shows that a PRP is a PRF except for negligible probability $\frac{q(n)^2}{2^{-l(n)}}$. My computations show me that the same argument, perhaps with minor mathematical ...

I am working in the area of lattice-based cryptography. i would like to know implementation using python in Internet of things. suggestion please.

I have a customer with an existing ticketing system that generates tickets for events like theaters, movies, football and so on. The information in each ticket is encoded in a 16 decimal digit ...

What is the running time complexity (average or worst case) of common arithmetic operations in number fields? In fact, I'm only interested in the integer ring of the quadratic extension $\mathbb{Q}[\...

I've read the sources of ZKBoo where they transformed arithmetic operations of the SHA hash functions into a bunch of boolean ones. Where does this transformation arise from? How do you construct such ...

So I paid $ 3000 USD for an Antminer D3 at the end of 2017. When I received it I learned that the S9 was already out and that my new mining beast has pretty much been rendered obsolete. On top of ...

My professor has posted a couple of practice questions that so far I haven't been able to find the answer for and I was hoping you could help. DES would remain invertible—it would still be ...

In "Applications of Multilinear Forms to Cryptography" Boneh and Silverberg give "one-round n-way Diffie-Hellman key exchange protocol" as a potential application of n-multilinear mappings. If we ...

Assume HMAC function is used to generate a 6-digt integers time-based onetime password. As follows: $$K_h =\operatorname{HMAC}(k,t) = H((k\oplus\text{opad})\mathbin\| H((k\oplus\text{ipad})\mathbin\|...

It is not a one time pad. I can send messages to my partner in crime using only an 18 x 12 grid containing only the letters A,B,C,D,E,F - he can look at the grid I send him and using only 3 rules ...

I'm looking for a symmetric encryption algorithm with specific characteristic. Having a key $k$ a message $m$ returns a ciphertext $c$, where $E_{k}[m] \rightarrow c$ It should be hard to perform a ...

If in a curve $y^2 = x^3+ 7 \mod p$ ( ecdsa-secp256k1) p=115792089237316195423570985008687907853269984665640564039457584007908834671663 G=...

If the last 448 bits of a sha1 block input are known (only the first 64 bits are unknown). Is it possible to do a preimage attack using SAT solvers or something else? Or do I have to brute force all $...

CRT-based Verifiable Secret Sharing Scheme In this paper, section 4 Verifiable Secret Sharing Scheme, the dealer phase and the combiner phase are as follows: Dealer Phase To share a secret $d \in ...