Latest Crypto related questions

Score: 0
Eirtaza avatar
How to securly save ED25519 private key on hard drive
cn flag

I am developing an application which stores user's private Identity key (ed 25519) on user's hard drive without any security.

What are the best practices / standards to save private key on hard drive, so even if the filesystem is hacked, keys are secure.

Score: 0
Deterministic data masking
jp flag

We are building out data masking framework mainly to mask PIIs. Our scale is pretty large, and masking will be done at ingest time, so we want the masking to be done in a very performant manner. Some of the constraints we have are that we would like the masking to be deterministic and reversible. I have looked at AES encryption to encrypt PII, especially AES SIV, on my macbook, it takes around ~2 millis ...

Score: 1
Hormoz avatar
Disparity between PyNaCl docs and libsodium docs
us flag

So if we look here, it shows that libsodium uses three 3 different algorithms for this, which sounds weird to me, cause nothing indicates that anything besides Curve25519 is used in those specific functions (the boxes specifically take private and public keys and nothing indicates there is any key generation for XSalsa20):

https://doc.libsodium.org/public-key_cryptography/authenticated_encryption#algo ...

Score: 1
mdmb avatar
E2EE with passwords at login?
cn flag

Imagine a scenario:

  1. Alice and Bob want to use a platform where they log in using email and password. The platform can be accessed on desktop and mobile devices.
  2. Alice would like to store encrypted information in a database or send encrypted files to an S3 server
  3. Bob will be able to fetch this encrypted information (data + files) if the server allows to (Alice granted Bob access to this data)
  4. Both Bob an ...
Score: 1
Verifiable Delay Function: Trusted Setup
tv flag

Efficient Verifiable Delay Function paper suggested that there is two way to construct the group. One of them requires trusted setup in the sense whoever constructs the RSA unknown group order needs to destroy the factors otherwise fake proof can be constructed.

Another way is using a class group of imaginary quadratic fields. However, the paper didn't give an example of how it can be used. Is ev ...

Score: 2
Irad Nuriel avatar
Identifying the cheater in (3,5)-Shamir's secret sharing
lk flag

The problem I'm trying to solve: Identifying the cheater in (3,5)-Shamir's secret sharing when we can see only the 3 shares that were given to the system in the secret reconstruction process, and we can inquire the 3 people who inserted the shares into the system(they don't know what the other people inserted). Also, we have no knowledge about the correct secret, but we do know the wrong secret.

 ...

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 ...

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.