# All Questions

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13 views

### Which Exchanges have the crypto hardware wallets with super fast transaction speed?

Many exchanges claimed to be faster than other exchanges and am new in crypto. Anyone who can help me getting started with a super fast exchnage? or anyone who can suggest me about a real decentralizd ...
14 views

### AES decryption L lookup table

In L lookup table there is no value for 00 condition then what do we do when 00 occurs? Because of this 00 condition i am not getting the output if anyone know please help me to solve this
7 views

### what is the area of 8-input xor in Gate equivalent in 130 nm CMOS library? [on hold]

2 input XOR AREA (11 – 16 ) in GE (2.75 – 4) XOR 3 INPUT (22 – 26) IN GE (5.5 – 6.5) XOR 4 INPUT (30 – 31) IN GE (7.5 – 7.75 ) WHAT IS THE AREA OF 4 INPUT XOR IN GE?
45 views

### Are any block ciphers provably free of equivalent keys?

There are $2^n!$ possible permutations of an $n$-bit block cipher $E_k:\{0,1\}^n \rightarrow \{0,1\}^n$, and any given key $k$ selects one of these permutations at random. Define equivalent keys as a ...
16 views

### What is the possibility of collision of trailing 160 bits of Keccak_256, for any two differing public-keys as pre-images?

Earlier today I was answering a question on the ethereum SE site that analyzed the potential for more than one private key on curve secp256k1 (which maps to a distinct public key) to control the same ...
14 views

### Need help to decipher the following text [on hold]

Need help. The phrase, date, highlight and underlining is a clue of some what. Plus, also the snake head is a clue. I did this much: Instead of ------ ----- ------- these, ------ them. Let them guide ...
25 views

### what is the difference between self issued and an intermediate certificate

Hashicorp vault has an API they call Sign Self-Issued. The use case is for rotating root CAs. A user creates a new root self signed CA and then passes it to this API and what is returned is roughly ...
21 views

### What are the maximal possible locks [on hold]

Suppose, you and your friends have a few numbers of locks and you all want to share that numbers among yourselves securely using RSA based cryptosystem. You are using the private key as (5,27) and ...
25 views

### How to implement GSW13 using Helib or SEAL?

I want to implement the homomorphic encryption scheme proposed in GSW13, and make some changes to it, but seems that there is no library that has already been implemented it. Since this is a ...
57 views

### Zero Knowledge Proofs: to establish a public key cryptography encryption

I am very interested to know in the general sense how two parties who know each other are able to continue a conversation IF and ONLY IF they both earn the same salary. For example, we have a person X ...
59 views

### Why are some group representations much easier to compute discrete logarithm for? [duplicate]

The multiplicative group mod $p$ is isometric to the additive group mod $p-1$, yet computing discrete logarithms in the additive group is easy and completing discrete logarithms in the multiplicative ...
124 views

### Efficient way of generating a random number of N (less than 64) bits with exactly M bits equal to one [on hold]

Would there be an efficient way to implement a function with the following signature: unsigned long long int random_word(size_t n, size_t m) that would generate ...
48 views

### CCA security of this scheme

Let $k$ be uniformly sampled from $\{0,1\}^\lambda$, $F$ be a secure PRP with block length $\lambda$ and let $Enc(k, m)$ be such that it returns $c = (F(k,r), r \oplus F(k,m))$ with $r$ uniformly ...
50 views

### Do Partially Homomorphic Encryption schemes also suffer from noise overflow?

Do PHE schemes in general also suffer from noise overflow problem?
214 views

### Randomness Testing of Cryptographic Algorithim

I am new to algorithim randomness and confused at I guess a basic level question. Is it common for any cryptographic algorithim to have repetitions in its output i.e.let say 34 and D8 are two ...
159 views

### How can we effectively compute the sqrt of some element in the group?

I only know one way, if this group is a cyclic group, and we know the element can be expressed in $g^m$, then $g^{(m/2)}$ is the answer. Another question, if $m$ is an odd number, can we be sure ...
20 views

### Does BLS aggregating signatures allow duplicate signatures?

If there is a message $m_1$ that $H(m_1) \rightarrow g^r$ and there is another message $m_2$ that $H(m_2) \rightarrow g^k$, where $g^k$ is also a generator of $G$, is this possible? then $g^r$ could ...
81 views

### Statistical Analysis of Cryptographic Hashing Algorithms

I was wondering how can I use NIST Statistical Test Suite to check for the randomness of output generated by a cryptographic hashing algorithm, let say SHA-256? To be specific, how will I generate ...
29 views

### 1-out-of-2 Oblivious Transfer Security

Just started reading Oblivious Transfer. I am searching for a proof of security based on RSA implementation but I can't find anything simple to understand. Can someone direct/show me to an easy to ...
50 views

### Pollard's $(p - 1)$ factorization method runtime

Wondering if anyone knows a good reference for Pollard's $p-1$ algorithm's runtime? I was looking on the Wikipedia page and the runtime cited there is $\mathcal{O}(B\cdot \log B\cdot \log^2 n)$. ...
71 views

### How are Data Science and Cryptography related?

Is there any interesting connections between Data Science And Cryptography. Data Science involves using Statistical Analysis to analyze data while Cryptography also involves Statistics in ...
53 views

### How does the challenger choose the message randomly in the one-wayness security game of PKE?

I have read some papers that give the definition of one-wayness of PKE schemes. Let $\Pi = (G,E,D)$ be a PKE scheme, and the security game of OW-CPA is defined as follow: \mathrm{Adv}_{\Pi,\...
73 views

### Nonce-misuse-resistance scheme applied after the fact to AES-GCM for defense in depth?

This is a follow-up to a previous question about encrypting IV/MAC results from AEAD ciphers. I have a system I'm working on that needs to use standard (NIST/FIPS) cryptography, at least for its ...
26 views

### Classification of BFV and CKKS scheme?

I would just like to ask what is the classification of both BFV and CKKS scheme are they Somewhat Homomorphic or Fully Homomorphic? Brakerski/Fan-Vercauteren (BFV) [Brakerski12, FV12, BEHZ16, HPS18] ...
121 views

### Use a SHA256 as a key for AES256

Is it safe to use the SHA256 of a hard-to-bruteforce string as the key to encrypt data with AES256?
104 views

### Is it safe to reuse the password when using AES-CTR with scrypt?

I want to encrypt several files with the scrypt encryption utility. Here is an overview of its file format, which gives an indication of what it does: ...
32 views

### In using Boolean Circuits model of Computation in Homomorphic Encryption why is is considered fast?

I am currently doing some reading on Homomorphic Encryption for research purposes and based on my reading using the Boolean Circuit Model of Computation specifically in regards to Fast Fully ...
6 views

### CP-ABE implementation in cpabe toolkit

I have designed a CP-ABE scheme which is different from original scheme by bethencourt. Now the cp-abe toolkit supports the original scheme and in order to use the toolkit for my scheme I have to ...
41 views

### Finding and matching SHA512 Unsalted Hash

We are given a list of possible strings, there are $32^{16}$ ($=2^{80}$) to be exact. We also have the unsalted SHA512 of the original target string. How long would it take to go through those ...
32 views

### What does (06) in “CRL Signing (06)” mean?

In "Certificate details -> key usage -> CRL Signing (06)", what does "(06)" in "CRL Signing (06)" mean?
60 views

### Is it possible to construct a hash-based public key encryption scheme?

I know hashes can be used to construct symmetric encryption schemes (HMAC running in counter mode), signature schemes (SPHINCS), pseudorandom generators, etc. One thing that's missing is public key ...
345 views

### Algorithm to find primes $q$ and $p$ with $q\, |\, p - 1$?

I understand that if $p$ is prime then $p-1$ must be composite (at least divisible by $2$ as it is even). But how does an algorithm find a prime $q$ such that $q \cdot r = p - 1$. I thought prime ...
31 views

### why is index “a non-negative integer less than $2^{64}$” in the KDF for UMACs?

https://tools.ietf.org/html/rfc4418#section-3.2.1 describes the parameters for KDF as follows: ...
34 views

### Hey, anyone know if this is a color cryptography? If yes what? [on hold]

Me and a group of friends are solving an ARG, we found some videos where every frame was an image like this one.
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### Are there any symmetric Partial Homomorphic Encryption Schemes?

Note that I am asking specifically for Partial Homomorphic Encryption (PHE) schemes and not Somewhat Homomorphic Encryption (SME) schemes. I believe there are several SHE schemes that are symmetric ...
82 views

### RSA, factoring with middle known bits of one prime?

It was shown by Coppersmith, that we can factor the RSA modulus with half of the most significant bits of one of the primes. And for the lsb case, assume that we known $p_0,k$, and $p=p_12^k+p_0$. ...
34 views

### Decrypting a weak PRNG Mersenne Twister Stream Cipher

I am currently working on the crypto-challenges presented here. I created a simple stream cipher using a Mersenne Twister RNG. It basically works as follows: Seed a RNG with the key (basically up to ...
34 views

### Generating anomalous elliptic curves with given order [on hold]

First of all please see this paper, I want to fully understand the section 3 and 4 of this paper and write a script that generates an anomalous elliptic curve with given prime order. Furthermore how I ...
43 views

### General factoring and one-way functions

Let a function $f$ be one-way, if there exists a probabilistic polynomial time algorithm to find the preimage of $y = f(x)$ for uniformly chosen $x$ with non-negligible probability. Define the ...
342 views

### What security risks does exposing the size of the plaintext entail?

For this question my focus is exclusively on symmetric block ciphers (with a particular interest in AES256 in CBC mode). I have read much discussion on various ways to pad the plaintext so that the ...
5k views

### How do I detect a failed AES-256 decryption programmatically?

I have implemented a simple encryption/decryption program based on AES-256 in CBC mode1. Actually, it is more precise to describe it as a compression+encryption / decryption+decompression program. ...
34 views

58 views

### RSA vs Elliptic Curves

I am currently reading about how more efficient and ''light'' is ECC compairing to RSA as far as key generation is concerned. My question is simple, why does RSA continue to be used today (ex.SSL) ...