Questions tagged [secret-sharing]
Secret sharing refers to splitting a secret among multiple parties so that together they can reconstruct it. All parties, or just a threshold number of them, can be required for reconstruction. If fewer than the required number of parties participate, no information should be leaked about the secret.
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Preserving location privacy
What are cryptographic techniques that could be used so that if I wanna to enable a server to send message to certain nodes in a network with preserving the privacy location for them ??
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Question regarding reconstruction vector in LSSS
Suppose we have a policy $A \wedge ( D \vee (B \wedge C))$ with attributes ${\{A,B,C,D}\}$. The set of subsets of attributes which satisfy this policy is ${\{{\{A,D}\},{\{A,B,C}\},{\{A,B,D}\},{\{A,C,D}...
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Reconstruction vector in Linear secret sharing schemes
Suppose we have a policy $A \wedge ( D \vee (B \wedge C))$ with attributes ${\{A,B,C,D}\}$. The set of subsets of attributes which satisfy this policy is ${\{{\{A,D}\},{\{A,B,C}\},{\{A,B,D}\},{\{A,C,D}...
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Eliptic curve verifiable secret sharing
I am implementing the following the algorithm instructions as shown in 1 (section IV, B).
When trying to verify the share given the commits, $a_jG$ verifier $i$ checks whether $f(i)G=\sum_{j=0}^{t} (...
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1answer
541 views
Reverse Shamir's Secret Sharing Algorithm?
Shamir's Secret Sharing algorithm works by breaking a single secret to multiple parts. While it is trivial to implement the reverse in a $n$-out-of-$n$ scheme, how would one implement an $m$-out-of-$n$...
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582 views
AES encryption using MPC SPDZ protocol
I'm reading the article about SPDZ protocol for secure multiparty computation (and also improvements for offline phase like MASCOT).
However I'm thinking about practical application of SPDZ for AES ...
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$t$-out-of-$n$ Secret Sharing over $\Bbb Z_2$?
Is it possible to construct a $t$-out-of-$n$ secret sharing scheme over $\Bbb Z_2$?
Shamir Secret Sharing allows for an arbitrary threshold $t$ and an arbitrary number of participants $n$, but ...
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127 views
Number of possible access structure with $n$ person
I want to count number of possible access structures in closed form(if possible) as a variable of $n$,the number of share holder. I have tried in several ways. Still no good progress. It is very hard ...
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Multiparty secret generation protocol
The goal is to create a secret S on a trusted server by having users A, B and C each send a private seed to the server, in such a way that any 2 of them can later recover S by resubmitting their ...
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1answer
157 views
Minimal size of share in Shamir's Sharing Scheme
Why does the combined shared key in Adi Shamir's Sharing Scheme have to be smaller or equal than each secret share?
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1answer
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Enforcing Randomness in Malicious Setting
I was going through some lecture notes where it said that if we have a 2-party protocol that requires both the parties to generate random integers during the course of protocol, then if we migrate the ...
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3answers
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Distributed Shamir's secret sharing
Wikipedia on its page for Shamir's secret sharing scheme provides a python implementation that applies the idea. This algorithm will generate a (k, n) threshold scheme so for example we could split a ...
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Optimized Random-OT Security in Standard Model
I was going through the paper - " Efficient Oblivious Transfer and
Extensions for Faster Secure Computation" by Asharov et al. where the authors propose an optimized OT protocol along with a Random-OT ...
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1answer
166 views
Can Secure Multi-party Computation be used to reconstruct secret shares?
When using Shamir's Secret Sharing is it possible to use Secure Multi-Party Computation to reconstruct the original secret without revealing one's secret share?
When searching I have found results ...
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168 views
A method for creating distributed public key for ECDSA, what are the risk factors?
There is quite a bit of literature on distributed ECC signing without a trusted dealer. Published works are mostly overly complicated, so I am proposing this simple technique which I am sure if it is ...
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Threshold signature without revealing id of signers to the recombiner
I want a threshold signature t out of n algorithm where set of t signers are not known before hand and want to remain anonymous after signing. How is recombination possible if id of signer is not ...
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2answers
318 views
Can we use Shamir secret sharing conversely?
In Shamir secret sharing scheme, we have a secret and then the shares are generated based on the secret. The question is can we generate the shares before knowing the 'secret' (which is uniformly ...
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1answer
294 views
Does adding a random number to my data make it secure?
Say I have some real valued data that i want to keep secure. Now I have to pass on some modified version of the data to a second party for some computation, but i do not wish to reveal my data to the ...
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2answers
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Can I prove my app uses randomness right way?
We are developing an iOS app which employs Shamir Secret Sharing algorithm. We made all possible steps users can trust us. We can't remember their secrets nor we can save encoded fragments. But they ...
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1answer
673 views
Combining multiple cryptographic keys to generate an encryption key
We have a system that has several SecretKeys (for example, one for a user, and one for us). We want to encrypt data in a way that requires all of those keys to be available in order to decrypt.
I ...
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How to reversely compute from hash [closed]
What are practical methodologies to derive the following ciphertext:
1bd0d370b262d748b21c40cc7e5746642b4c06079a224c65e443e429289753c2
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1answer
114 views
Secure scheme to share symmetric key using asymmetric keys and certificates with N parties
I need to distribute symmetric AES key into number of end points which will use it to decrypt data. The AES key will be the same on all end points, it is not possible to generate unique on every end ...
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83 views
Conditional $k,n$ secret sharing
I would like to know if there is a way to place a condition on $k$-out-of-$n$ secret sharing such that out of $k$ participants who can pool their shares to reconstruct a secret, one of them should ...
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390 views
Additive homomorphic secret sharing
I am new to cryptography esp, homomorphic encryption. I would like to know if the following is possible using something similiar to additive homomorphic secret sharing. Please apologize me if its too ...
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1answer
213 views
Interpolation in the Exponent (Shamir Shared PRF)
Trying to implement the Diffie-Hellman distributed PRF mentioned by Cachin : https://cachin.com/cc/papers/abba.pdf.
It makes sense to me... just use the same Lagrange coefficient I'm using to combine ...
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1answer
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A problem in secret sharing and mixed operators over $\mathbb{Z}$
Recently, I studied an article in which it was written that having $(A-B)\oplus C$ and $B\oplus C$, we cannot find $A$. The authors used this result to build a secret sharing scheme, but they did not ...
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What SMPC protocols make use only of additive secret sharing?
In Appendix G of the Hawk paper, where it talks about financially fair SFE, it mentions that it's possible to run a SMPC protocol where, at the end, each party has a share of their own output y, and a ...
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1answer
101 views
Tampering with Shamir's subshares
Suppose a set of Shamir's redistributable-secret-sharing participants issue a redistribution of subshares.
I envision this as a series of points on a line (2 of N, is planar, easy to think about). ...
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1answer
110 views
Shamir's Secret Sharing - Impersonating the Dealer
I understand that Shamir's Secret sharing has nothing to do with the methods that are used to share and later recover a key.
That means then, the secret is only as secure as the methods used in ...
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1answer
131 views
Shamir's Secret Sharing Computation time
Hello for my thesis I am making research about SSS computational time.
Based on (K,N) threshold scheme
Where K is the minimum number of shares to rebuild the secret and
N is the number of shares ...
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1answer
59 views
security of multiplicative secret sharing
I was having a read of this question: "Is multiplicative secret sharing secure?"
posted in 2013 which asks if the simple multiplicative scheme is secure.
Everyone agreed that it was information ...
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2answers
137 views
Is it generally considered acceptable for app owners to be able to retrieve private keys from users when their apps offer end-to-end encryption?
E2EE promises that data sending between two endpoints can be decrypted by only those two endpoints. If an app offers E2EE but still has functions to retrieve private keys from users for any purposes ...
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1answer
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Creating a share of a random shared secret [duplicate]
I am interested to know if there is a solution to the following scenario:
Assuming we have $n$ party members, is there a scheme that at the end of it, every party member $i$, holds a shamir's ...
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Are there any information-theoretically secure verifiable secret sharing protocols with t=n?
Disregarding matters such as efficiency and round complexity, can verifiable secret sharing be done in a way such that the secret cannot be decoded unless you have all n shares, and that this ...
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1answer
182 views
Baek and Zheng’s Threshold Cryptosystem - limit on threshold?
I have just completed an implementation of Simple and Efficient Threshold Cryptosystem from the Gap Diffie-Hellman Group by Baek and Zheng and am hitting a problem with high values of the threshold. ...
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1answer
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ECIES: key derivation function and symmetric encryption scheme
I am using an elliptic curve library which provided me with a shared secret using my secret key and a foreign public key. Unfortunately an ECIES is not available in the programming language.
I would ...
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319 views
Combining Shamir's schemes
I am learning about Shamir's secret sharing scheme and I've come across this problem:
Let's suppose we have a combination of a (3, 6) and (1, 2) Shamir's schemes, where participants $P_1$ and $P_2$ ...
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3answers
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How to forge a Shamir secret share?
On this website, we have a lot of questions and answers devoted to Shamir secret sharing. We make it clear that Shamir secret sharing does not guarantee integrity. When we want integrity, we need to ...
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2answers
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Undetectable cheater in Shamir's Secret Sharing scheme
Consider Shamir's Secret Sharing scheme with $n=5, t=3$ (i.e, there are 5 shares, and when we have 3 of them we can reconstruct our secret $s$). Let $f(x)$ be the dealing function, i.e the secret $s$ ...
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Prove that shares can reveal a seceret key. in a secret sharing scheme
I am trying to build a cryptographic system that has several components and ran into a problem with a secret sharing scheme.
Let $v$ be a value we are interested committing to.
I generate a ...
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1answer
289 views
secret sharing with 3 parties under constraint
Suppose we have $3$ parties Alice, Bob and Charlie such that Alice can't talk with Bob.
Suppose that Alice has some string $x\in\{0,1\}^n$ and Bob has a string $y\in\{0,1\}^n$.
Suppose that Alice ...
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1answer
135 views
How can I prove that it is impossible to find a cheater in shamir secret sharing?
Three participants Quadratic polynomial, one cheater. The Cheater discloses a false (x,y) pair I need to prove that any one of the truth-telling participants can't tell which of the others is the liar....
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What are the weaknesses of Shamir's Secret Sharing?
We just learned about this in school but i don't quite get the weakness of this method. If we let's say have used a 64-bit secret key to encrypt a file and then we split the key into 2 pieces of 32-...
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741 views
Multisignature or Multi-password File
I want to create a file that I could give to 3 trusted friends, and allow any two of them to decrypt it when together (or in sequence when not physically in the same place). This is similar to a ...
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1answer
81 views
Is there a cryptographic scheme that allows joint encryption using a shared secret?
I'm looking for a type of algorithm that could be used to encrypt text with a shared secret $S$. What I would like to have is the secret to be broken up in three pieces, where any combination of two ...
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1answer
201 views
Secret Sharing Scheme, with joining players, no central entity
I am facing the the following problem:
Lets assume i have a secret, $S$, I want to share it to $N$ players so that $K$ of them can cooperate in order to obtain the secret ($K$,$N$ scheme).
Is there a ...
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1answer
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Is it safe to derive secret from alice's private key and alice's public key?
I'm using secp256k1; in normal scenario alice.privateKey and bob.publicKey (or vice versa) is used to derive the same ...
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Ecash - Probability of catching a user using secret splitting who duplicates the coin
For detecting double spending, secret splitting is used. If a user duplicates the coin, then there will be two different transaction items in transaction list. What is the probability of catching a ...
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Determining the Shamir's secret sharing scheme for the following problem
I'm having trouble solving the Shamir's Secret Sharing scheme for the following problem that states:
Problem: A certain military office, which is in control of a powerful missile, consists of six ...
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1answer
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Determining the secret using the Blakley's scheme?
I am solving a example with Blakley's scheme problem. The issue that I am having is using the row operation to determine the secret $x_{0}$. So what I have so far is:
Given three planes: $z = 7x + ...
