# All Questions

18,940 questions
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### Pokemon rumble u encryption

Is someone here able to decrypt and encrypt the figure dumps data for pokemon rumble u figures? In order to change the character and moves etc then put them on an empty topaz 512 tag? I think they ...
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### Security of an Elliptic Curve Public Key with a “Small” x-coordinate

Consider an elliptic curve over a finite field $F_p$ with $p$ prime and order $n$. Let $Q$ be a generator for the field. Given a public key point $P = aQ$, suppose we have an algorithm that finds an ...
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### Is there a public-key system that can chain?

Does there exist any asymmetric cryptosystem that has the following properties: If I know somebody's public key PBK_1 and my own key pair (PVK_2,PBK_2), I can construct a new public key PBK_3 such ...
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### Key exchange without an underlying semigroup

I am wondering whether there is a general reformulation of perfect forward secrecy for 2 party key exchange in 2 messages using semigroups. I am looking for references, which would discuss such ...
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### Does such a cryptographic protocol exist?

Persons A, B and C put x€, y€ and z€ in a pot, respectively. Suppose that anyone can make a withdrawal from the pot as long as they prove they have such a right and that the x€ that B deposited is ...
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### How long does it take to crack RSA 1024 with a PC?

Using an Intel Core i5 CPU, how long does it take to crack RSA using a key size of 1024 bit (generated using a secure key pair generation function)? Suppose for instance that we have thousands of ...
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### BIP39 Path in ledger nano s [migrated]

On ledger nano S, you are given a BIP39 24 word mnemonic. What is the path to the address used? Is it m/44'/144'/0'/0/0 ? Say for example I use the address generated by the ledger nano s to store ...
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### How to calculate RSA group signatures

RSA group/ring signatures, how are they calculated?
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### SHA1 padding on length extension attack

I was recently trying to replicate a length extension attack on SHA1. I implemented the registers state and also the new padding implementation (with the whole of the message that I want to extend). ...
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from Can I clone a LUKS container? You can, but it breaks security, because the cloned container has the same header and hence the same master key. You cannot change the master key on a LUKS ...
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### Attack Scenario for mutual key authentication protocol based on a Symmetric key cryptography algorithm

Here, the R is a challenge and KAB is a key known only by Alice and Bob. The +1, in R+1 is a nonce. I need to find 2 attack scenarios on how the protocol can be broken. I have been able to find one, ...
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### Choice between appending or prepending nonces to ciphertexts

I understand that when using CTR mode, it is usually secure to append or prepend the nonce to the resulting ciphertext, whether the nonce is before or after the ciphertext being unimportant. However, ...
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### Cipher Block Chaining - How do you change the plaintext of all blocks?

I've just read about CBC encryption and decryption and was wondering how you can change every plaintext block? Let's say you have an initialization vector, 3 ciphertext blocks, know each block-cipher-...
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### What is the difference between a prime field $F_p$ and binary field $F_{2^m}$ in the elliptic curves?

I am using elliptic curves to encrypt a VOIP application, but I can not understand the difference between using an algorithm based on a binary field or a primary field. I would like for someone to ...
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### Where does the certification come from

In the book : applied Cryptography 2nd(Bruce Schneier), chapter 2 I don't understand step(5), the 'certification' didn't mention in previous steps. does it means 'a statement that he has received ...
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### Usage of the nth-root function in cryptography

Having offered a fast integer nth-root algorithm to a bigint library that is also used for cryptography I was asked if it does its work in constant time, so I took a look at the literature to see how ...
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### Is this paper's technique for factoring RSA 2048 with noisy qubits realistic?

A paper titled How to factor 2048 bit RSA integers in 8 hours using 20 million noisy qubits has just come out which proposes a technique to factor RSA keys with moduli up to 2048 bits with a design ...
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### What state does a qbit look like before it collapses [migrated]

Which is the correct depiction of a qbit state showing the possibilities before it collapses? Is it like: MODEL 1: 1000 0100 0010 0001 MODEL 2: 1000 0100 0010 0001 0111 1011 1101 1110 MODEL 3: ...
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### design a secret sharing scheme [on hold]

Suppose you are an army cryptographer. In the army there are one General and five Lieutenant Generals. Your mission is to design a secret sharing scheme allowing one General and one Lieutenant General ...
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### IETF Recommendations for preparation for PQC- clarify in what way they are referring to bits [on hold]

In the IETF mtg in 2017, in the recommended actions, are they saying leave enough flexibility in terms of bit usage for key sizes to throw in/switch out anything NIST picks out, or sufficient key ...
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### Root Certificate Authority of National Identity Cards [on hold]

We're collecting a list of all the Root Certificate Authorities of National Identity Cards but due to language issues and the relative obscurity of the government pages on which they are listed, we're ...
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### Do Weil, Tate, and Ate pairings exist on all elliptic curves?

I don't know much about the math behind elliptic curves. Do Weil, Tate and Ate pairings exist on all elliptic curves? If the answer is negative, then what pairings do MNT, BN and SS curves have? ...
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### What does the number 256 in pairing curve BN256 indicate?

There are many pairing based elliptic curves like MNT curves, BN curves, SS curves etc., When we say BN256 curve, what does the number 256 indicate? Is it some group order or number of bits required ...
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### Is there a concept of embedding degree for non-pairing based elliptic curves?

From this post, I learned the concept of embedding degree. Intuitively, if embedding degree of an elliptic curve $E(F_p)$ is $k$, it means there is a way to transform points in $E(F_p)$ to $F_{p^k}$. ...
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### How would I get the issuer's public key from two RSA-signed certificates? [migrated]

I'm trying to get the issuer's public key from two SSL client certificates signed with a 2048-bit RSA key, SHA-256 hashing and PKCS#1 padding, as I only know the issuer's DN and I wish to verify all ...
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### Signal Protocol Header key encryption initialization vector

In Signal Protocol when you use a Double Ratchet you have 2 options: Normal encryption = header + ciphertext Encrypted header encryption = ...
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### Using Chameleon-HF-enabled security in practice

If one were to implement a digital signature scheme that is only EUF-CMA-secure when using Chameleon Hash Functions, would one actually use a Chameleon Hash Function or a standard cryptographic hash ...
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### Construction PRF from PRG

As discussed here, a classic and secure construction of PRF from PRG is: $F_k(x_1x_2\cdots x_n) = G_{x_n}(\cdots(G_{x_2}(G_{x_1}(k)))\cdots)$ where $G$ is a secure pseudorandom generator. I was ...
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### How to actually compute the statistical distance?

I have an algorithm for discrete sampling that I've defined. This is to say that $A$, upon input some pdf $p(x)$, outputs samples from the pdf $p(x)$. There are some nuances (you have to make the ...
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### “Work factor” and “iteration count” nomenclature in adaptive functions

In adaptive functions like PBKDF2 / bcrypt I often read people refer to "iteration count" and others refer to "work factor", and they seem to be used interchangeably (even though they're not - the ...
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### Is NIST testing all the round 2 submissions to quantum-resistant crypto?

Is NIST confirming the self-published quantum-resistant crypto round 2 data and do they make that available to the public when they do?
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### RSA How to find the exponent ($e$) of the Public key with the values $p$ $q$ and an example are given

I'm wondering if it's possible to find the public exponent ($e$) with an example and the (rather small) values of $p$ and $q$ given. Currently the only option I found is bruteforcing this value, but ...
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### Binary Cryptography Problem [on hold]

i have some problem about a binary crypthography. i have the code and the solution but i can't found the key to understand the meaning. our value is ...
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### Is it possible to verify the requesting user for a REST transaction secured by JWT at a later date? [migrated]

I have a React (Javascript) single-page application that authenticates users via username/password/MFA to Keycloak, receives a signed JWT upon successful authentication, and then uses that JWT to call ...
108 views

### Does lagrange interpolation work with points in an elliptic curve?

Defining the lagrange interpolation for $x=0$ as $\mathcal{L} = \sum_{i=1}^{t+1} y_{i} \cdot l_{i}$ with $l_{i}$ as the lagrange basis polynomials. Does this hold if we apply the elliptic curve ...
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### EC Key Compression

Using the secp256k1 curve, will the below yield the same result? Generate private key -> compress private key -> generate public key Generate private key -> generate public key -> compress public key ...
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### How to securely store encryption keys in android? [migrated]

I want to know how to securely store encryption key in Android(API Level < 23)? What is the best scenario to protect encryption and secrete keys?
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### How to encrypt data when send over https [on hold]

I know its not practical to encrypt data when you send over https for widespread consumer use. But if i had to, how would i do that?. One way is for the server and client to agree upon an additional ...
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### What makes the quadratic residuosity problem hard?

The quadratic residuosity problem is the problem of determining whether, for given $r$, $m$, $\exists a.a^2\equiv r\mod m$. This problem's believed to be hard to solve in general (e.g. an efficient ...
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### Why did Rabin use $x(x + b)$ instead of just $x^2$ in the original paper?

Encryption in the original Rabin scheme took a message $x$ and computed $x(x + b) \bmod n$, where $0 \le b \lt n$ and $n$ is the product of two secret primes $p$ and $q$. The private key is defined as ...
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### Is this man in middle atack possible in quantum cryptography? [duplicate]

Lets consider there is channel between Alice and Bob, sequered with quantum cryptography. To put it simple, Alice is left, Bob is right and the quantum states are 'up' ~ U and 'down' ~ D. Alice ...
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### DES parity bits

The key is nominally stored or transmitted as 8 bytes, each with odd parity. According to ANSI X3.92-1981 (Now, known as ANSI INCITS 92-1981), section 3.5: One bit in each 8-bit byte of ...