Latest Crypto related questions

Score: 1
Gennaro & Goldfeder Key Generation Protocol
cn flag

As I am going through the “Fast Multiparty Threshold ECDSA with Fast Trustless Setup” paper by Gennaro & Goldfeder, 2018, I am stumbled by the key generation protocol (Sect. 4.1, p.10):

Clip of the key generation protocol from Gennaro & Geldfeder, 2018

In Phase 1, they create a (commitment, decommitment) pair using a commitment scheme. Earlier in the paper, they mention that “in practice one can use any secure hash function H and define the commitment to x ...

Score: 1
chang jc avatar
Encryption algorithm by a vectored key and the error is Proportional to the difference between input key and real key
id flag

I want to find an encryption algorithm which provides the functionality described below.

Given a key (a vector Vkey) and a data (an image), use this key to encrypt the image; the encrypted image can not be identified afer encryption.

When decrypt, if:

  1. use a key = Vkey to decrypt, the decoded image is the same as original one without error.
  2. use a key = Vkey_1, and diff(Vkey, Vkey_1) < threshold, ...
Score: 0
Verifying Merkle root correctness without completely reconstructing the tree
cn flag

Lets say Alice has a list of values, and Bob sends Alice a Merkle root that he claims is for this list of values. The Merkle tree construction algorithm is mutually known of course.

Alice can then pick arbitrary values from the list and ask Bob for their Merkle proof.

Lets say Alice wants to avoid constructing the whole tree to verify Bob's Merkle root. How sure can she be that Bob's Merkle root is  ...

Score: 1
Rafa avatar
Does the bit generated password using QKD protocols need to be converted to another base?
es flag

I am currently implementing some QKD protocols using Qiskit and I came up with the following question: After the protocol is finished, a true random password is generated using 0s and 1s, however, and here my question, do these passwords need to be converted to another base? Maybe hexadecimal? Or are they used as they are?

When I mean by used is to using them, for instance, as a key for the one t ...

Score: 1
rzxh avatar
SS/HE/GC/OT secure integer comparison
de flag

I have been reading some papers to find a 'faster' way to compare two integers without revealing their real values. But I think I'm a bit lost in those papers due to my limited knowledge in cryptography. There are some papers comparing the efficiency of HE based/ GC based/ OT based protocols, for example https://eprint.iacr.org/2016/544.pdf by Geoffroy Couteau(still a bit hard for me to understand th ...

Score: 5
kentakenta avatar
Zero-Knowledge Proof of Equality between RSA Modulus and Prime Order Group
kn flag

Assume there is an RSA public key $(e,n)$ such that factarization of $n$ is unknown to both prover and verifier parties. We also have a prime order group $G$ and a generator $g$ for the group. For $m\in QR_n$, is there a zero-knowledge proof protocol to prove that $C_1=m^e$ and $C_2=g^m$, for public values $(C_1, C_2, e, n, g)$?

Score: 6
Bob avatar
Why are elliptic curves over binary fields used less than those over prime fields?
cn flag
Bob

In practical applications, elliptic curves over $F_p$ seem to be more popular than those over $F_{2^n}$. Is it because operations over prime fields are faster than those over $F_{2^n}$ for the same security level?

Maybe it is my imagination. I just see many more open projects using elliptic curves over $F_p$ but not as many over $F_{2^n}$.

Score: 3
jacobi_matrix avatar
Uniform and Non-Uniform PPTs
in flag

While reading the paper

I stumbled upon the case in which it was necessary to state whether the authors were assuming uniform or non-uniform attackers. For what I know, non uniform PPT are basically a sequence of PPTs, so $\mathcal{A}=\{\mathcal{A}_1,\mathcal{A}_2,\dots,\math ...

Score: 4
fgrieu avatar
Quantitative reduction of Schnorr's identification scheme to DLP
ng flag

Question

I seek a quantitatively better proof of theorem 13.11 in Katz and Lindell's Introduction to Modern Cryptography (3rd edition) (or nearly equivalently, theorem 19.1 in Dan Boneh and Victor Shoup's freely available A Graduate Course in Applied Cryptography). The proof is about the Schnorr identification scheme for a generic group $\mathcal G$ of prime order $q=\lvert\mathcal G\rvert$ and genera ...

Score: 1
hola avatar
Complexity of Hash mining/signing
bd flag

While reading about mining in crypto currency, I found that it requires some leading bits of a hash function output to be 0. This boils down to preimage resistance of the hash function, hence done with exhaustive search.

My question, say I have an ideal hash function that gives 128 bit output and I want leading 4 bits be 0. What is the expected number of time I have to run it (with randomly chose ...

Score: 2
Bob avatar
Parameters in RLWE
cn flag
Bob

Let $n, q, \sigma$ be the polynomial degree($x^n+1$), coefficient modulo, and the standard derivation, respectively. I often see some parameters such as enter image description here

For RLWE, we can use the CRT to decompose the $\text{RLWE}_{q}$ to some $\text{RLWE}_{q_i}$ for $1\leq i\leq l$, where $q = q_1 q_2\cdots q_l$, then when we consider the security of RLWE, we should take $\log q$ or $\log q_i$ to be considered?

Score: 1
CrypTool RSA Features
in flag

I am attempting to manually encrypt a plaintext message (message = MI) using RSA.

Manual Encryption of Plaintext Message

I receive an answer of: 33,264 and 21,164.

When I enter the same plaintext into CrypTool to confirm that my calculations were correct, I receive a different answer:

CrypTool Screenshot

What am I doing incorrect? How can I obtain the same result as CrypTool?

Score: -1
Am I Doing RSA Correctly?
in flag

I am trying to figure out how to complete RSA manually. I am trying to encode a simple block message (Mi). I used CrypTool to determine the encryption. When I "manually" computed the plaintext, I obtained a different number than what CrypTool provided. Can someone guide me? Am I doing the manual encryption for RSA correct?

RSA Manually

Score: 1
How does password_verify() function gets the salt from the password stored in DB?
sg flag

I am creating a simple Sign up and Sign in form using PHP. At the sign up, I create hash using password_hash() function and then store it in the DB. At the time of Sign in, initially what I did was created a new hash using password_hash() function again and then compared it with the stored Password hash.

This failed all the time because as I understand now, a new salt is used every time you creat ...

The Stunning Power of Questions

Much of an executive’s workday is spent asking others for information—requesting status updates from a team leader, for example, or questioning a counterpart in a tense negotiation. Yet unlike professionals such as litigators, journalists, and doctors, who are taught how to ask questions as an essential part of their training, few executives think of questioning as a skill that can be honed—or consider how their own answers to questions could make conversations more productive.

That’s a missed opportunity. Questioning is a uniquely powerful tool for unlocking value in organizations: It spurs learning and the exchange of ideas, it fuels innovation and performance improvement, it builds rapport and trust among team members. And it can mitigate business risk by uncovering unforeseen pitfalls and hazards.

For some people, questioning comes easily. Their natural inquisitiveness, emotional intelligence, and ability to read people put the ideal question on the tip of their tongue. But most of us don’t ask enough questions, nor do we pose our inquiries in an optimal way.

The good news is that by asking questions, we naturally improve our emotional intelligence, which in turn makes us better questioners—a virtuous cycle. In this article, we draw on insights from behavioral science research to explore how the way we frame questions and choose to answer our counterparts can influence the outcome of conversations. We offer guidance for choosing the best type, tone, sequence, and framing of questions and for deciding what and how much information to share to reap the most benefit from our interactions, not just for ourselves but for our organizations.