Questions tagged [data-privacy]
Data privacy refers to (cryptographic) methods to prevent the disclosure of sensitive (identifying) information of persons.
108
questions
5
votes
1answer
96 views
What is the best way to pseudonymise IP addresses while retaining the ability to identify those that share a subnet?
Background: I'm developing an app that is based around registered users voting on stuff, and I want to create a heuristic that involves IP addresses as one way to flag accounts for further ...
2
votes
0answers
20 views
What is the link between anonymous credentials and transactional pseudonyms?
Anonymous credentials are used to prove certain properties of a specific user without revealing any other information, and transactional pseudonyms are used to authenticate a user as the rightful ...
3
votes
2answers
80 views
Prove that $x$ is the sum of digitally signed numbers without revealing the summands
Imagine this:
Charlie chooses two integers $x_1$ and $x_2$ and signs each of these integers with the same private key.
Charlie sends the following to Alice:
$x_1$ and $x_2$,
the two signatures, and
...
1
vote
0answers
23 views
Looking for a (partly) anonymous signature
I am looking a way to sign a document, so that everyone could verify that one person out of a group did, but only a special person and/or the group could know who signed it.
Let's say, X chooses a ...
1
vote
1answer
57 views
Differential Privacy: Gaussian Mechanism when $\epsilon >1$, Laplace Mechanism when $\epsilon = 0$
In Differential Privacy resources, the limiting cases of $\epsilon, \delta$ are not justified well enough.
For example, on Wikipedia, it is said that Gaussian mechanism only works when $\epsilon < ...
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votes
0answers
41 views
Revealing percentiles of an ordered dataset without revealing its size
Given an ordered set $S$ of positive integers (eg. $S=\{503, 503, 520, 551...N\}$) I want to be able to reveal the percentile rank (eg. 503 is in the top 10th percentile) for each element of a ...
0
votes
0answers
20 views
Linking attacks on anonymized data
I'm working on a anonymization project and I got interested in linking attacks. For simplicity I only look at data in table format, such as xlxx or csv data. To anonymise such data the most common ...
0
votes
0answers
39 views
Is it possible to allow a user to log in if logged out without identifying them?
I have to verify that the user has registered and is currently logged out without identifying the user. Essentially, I am looking for privacy-oriented authorization mechanisms which prevent ...
1
vote
1answer
16 views
Sensitivy Maximization RAPPOR (Local Differential Privacy)
Hi I have a doubt at the end of the proof of the RAPPOR Algorithm, when they say the sensitivity is maximized when $b'_{h+1}=b'_{h+2}=...=b'_{2h}=1$ and $b'_{1}=b'_{2}=...=b'_{h}=0$. I don't ...
2
votes
1answer
85 views
Data Security and Encryption
I have a research paper on data security using proxy re-encryption, and I need to provide an answer to a reviewer's comment. However, I have no idea on what to do or how to answer it.
The security ...
0
votes
0answers
9 views
Directional vector privacy-preserving techniques
I'm new to cryptography, and I wonder if it's possible to temporarily track users by observing directional vectors in Mobile-Ad-Hoc-Networks, and if there are any methods, in case it is trackable, to ...
2
votes
2answers
48 views
What is $z_b$ in this introduction to Private Information Retrieval?
I was trying to read this introduction to private information retrieval. On page 12 of the document, a scheme for 1-DB private information retrieval is discussed. I was unable to understand one of the ...
2
votes
1answer
68 views
How to adapt the equation of Gaussian mechanism noise based on number of executions
I'm trying to build a differentially private machine learning model. I'm using the Gaussian mechanism to calculate the required noise amount based on pre-defined privacy budget value 𝜖
The equation ...
0
votes
0answers
36 views
Mechanisms for masking identifying unique IDs with non-identifying unique IDs to protect privacy?
I need to suggest mechanisms for masking unique codes in a database with different unique codes that are not derived from the original unique codes, but are equivalently unique in that they could ...
1
vote
1answer
93 views
Differential privacy what does "where the probability is taken over the randomness used by the algorithm" mean?
The definition of differential privacy is as follows:
A randomized mechanism $\mathcal{M}$ is $(\epsilon, \delta)$-differentially private, where $\epsilon \leq 0$ and $\delta \leq 0$, if for any ...
1
vote
2answers
179 views
Differential privacy noise that scales with $L_p$-sensitivity with $p>2$?
It is well-known that to make the result of a $\mathbb{R}^d$-valued query $(\varepsilon,\delta)$-differentially private, you can add noise to it. If you add Laplace noise, you need to scale the noise ...
0
votes
0answers
17 views
Check correctness of data using only publicly known variables and a server response
A smart contract (a publicly known program) needs to check if the data D is correct (belongs to some fixed set). It is by definition correct if our trusted server checks it and decides it's correct.
...
2
votes
1answer
56 views
The sensitivity in differential privacy with deep learning
In differentially private deep learning, the sensitivity is determined by clipping gradient norm (see Abadi et al.'s paper). In this paper, when the clipping gradient norm is $C$, the sensitivity is $...
3
votes
1answer
97 views
Laplace Inequality
I am trying to prove that if $r_i \sim Lap(0,1/\varepsilon)$ where $\varepsilon >0$ then:
$$Pr[r_i \geq 1+r^*] \geq e^{-\varepsilon}Pr[r_i \geq r^{*}]$$.
I know that for $r*>0$ it satisfies ...
2
votes
1answer
323 views
$(\epsilon, \delta)$-differential privacy: main motivation of $\delta$
I am wondering why (not how) we relax $\epsilon$-differential privacy to $(\epsilon, \delta)$-differential privacy. Is the main motivation to reduce the variance of the noise added to the query with a ...
1
vote
1answer
175 views
Advanced Composition (Differential Privacy)
I have a problem understanding the proof of the corollary of Advanced Composition
Theorem Advanced Composition:
For all $\varepsilon,\delta,\delta' \geq 0$ the class of $(\varepsilon,\delta)$-...
2
votes
0answers
80 views
Content Key Encryption for Multi-User data access
I recently worked out a concept for a use-case, but I'm not sure if my approach is good enough.
So I would appreciate feedback and things to look out for, as I'm fairly new to this field.
A User can ...
3
votes
1answer
125 views
Lemma KL-Divergence (Differential Privacy)
I am studying differential privacy and I got stuck again in proof of a lemma. Which is:
$D_{\infty}^\delta(Y||Z) \leq \epsilon$ if and only if there exists a random variable $Y'$ such that $\Delta(Y,...
1
vote
0answers
63 views
Is using Fiat-shamir Heuristic safe?
What I'd like to do is to have the Prover store a value x where x remains hidden.
From x, I'...
2
votes
1answer
135 views
Calculating the privacy that Renyi ($\epsilon, \delta$) Differential Privacy satisfies
I add differential privacy (DP) to my machine learning models by using PyTorch-DP. PyTorch-DP supplies me with the values: $\epsilon$ and $\delta $. I know that the $\epsilon$ tells us something about ...
2
votes
1answer
144 views
Differential Privacy: What is the 'game' between data holder and adversary?
I have been reading the Differential Privacy (DP) literature for some time to get familiar with it. I feel comfortable with the Math and Stats foundations of it, but I am suffering a bit from the '...
0
votes
1answer
278 views
how many iterations of SHA3 (keccak256) hashing would be required to provide reasonable protection for the following data structure?
((A , B , C) , (D , E , F, G, H))
Where:
A is 0x0-0xF, (1 of 16)
B is 0x00-0xFF (1 of 256)
C is an 8 digit integer
D is a one of a list of one hundred words padded to 12 characters
E is a one ...
2
votes
1answer
105 views
Compute euclidian distance on encrypted data
The scenario is described as following: Let $A$ an user that is transmitting an encrypted (with its own public key $PK_A$) data vector containing its position as $p = Enc(PK_A, [x,y])$ towards a group ...
0
votes
2answers
105 views
What is the implication for differential privacy if $\epsilon = 0$?
In pure differential privacy, the parameter $\epsilon$ represents the desired privacy loss. The smaller the $\epsilon$ is, the more privacy we can obtain. What happens when we want the privacy loss $\...
1
vote
1answer
75 views
Which is more secure PEPP-PT or DP-3T?
Which of these population tracking protocols is better from a cryptography point of view?
Pan-European Privacy-Preserving Proximity Tracing (PEPP-PT)
Decentralized Privacy-Preserving Proximity ...
0
votes
0answers
136 views
Encrypting conversation messages stored in database (symmetric encryption)
I have a chatting application like Slack/Discord.
In this chat application there chat groups and messages sent by users need to be encrypted in the database.
I do not need features like E2E encryption,...
0
votes
1answer
140 views
Adding the same noise to all element of a vector is Differential privacy
In Differential privacy, if we add a $N$-dimension private vector with $N$-dimension Laplace or Gauss noise, we obtain differential privacy. However, if we only generate a 1-dimension noise to add it ...
0
votes
0answers
44 views
Proving anonymous credential presentation
In a CL-based or CKS-based anonymous credential system, how can a verifier $V$ prove that a credential holder $H$ has presented it a credential that has been issued by an issuer $I$ without ...
1
vote
0answers
57 views
Comparison of end-to-end encryption and TLS
I am writing a comparison paper about security of electronic communication and I want to compare end-to-end encryption and TLS by giving two examples such as Whatsapp and Facebook Messenger. However, ...
0
votes
2answers
56 views
privacy enhancing techniques on image data
To give some context:
I am looking for a suite of techniques and tools that can theoretically enable me to conduct analysis such as classification on image datasets in a manner in which a naive ...
3
votes
2answers
823 views
Interpretation of advanced composition theorem of differential privacy
In "The Algorithmic Foundations of Differential Privacy" book, Advanced Decomposition Theorem (Thm 3.20) is stated as follows:
For all "$\epsilon, \delta, \delta' \geq 0$, the class of
...
1
vote
0answers
74 views
Sigma Protocol with Privacy-preserving Discrete Logarithms?
I've been reading up on Sigma Protocols and Fiat-Shamir Heuristic. There is a small problem I see here that is possibly already solved, but I'd like to know if it has a solution.
Peggy wants to prove ...
3
votes
2answers
108 views
What's the meaning of probabilities in differential privacy formula?
I don't understand what does it mean by "The probability is taken is over the coin tosses of K."
Does it mean, the probability distribution is generated based on exactly same data but only the ...
2
votes
0answers
60 views
Differential privacy RAPPOR article proof doubts
Recently I've been trying to understand the RAPPOR proof:
\begin{eqnarray*}
P(B' = b' | B = b^*) & = & \left(\frac{1}{2}f\right)^{b'_1}\left(1 - \frac{1}{2}f\right)^{1 - b'_1} \times \ldots \\...
0
votes
0answers
47 views
Two parties looking to share data anonymously
I've been struggling to find good info on how to do the following:
A(lice) and B(ob) each have a table of data (a and b ...
3
votes
1answer
125 views
Why does ε-differential privacy protect the subset of 1/ε edges in terms of graphs?
In the book The Algorithmic Foundations of Differential Privacy by Cynthia Dwork, Aaron Roth on page 24, databases that take the form of graphs are discussed.
We could on the other hand consider ...
1
vote
1answer
71 views
Facebook app-scoped identifiers and similar - implementing stateless ID obfuscation
After certain privacy concerns Facebook rolled out a bunch of changes to their APIs, one being "scoping" user identifiers per app. In effect, this means that Alice's canonical facebook user ID is ...
1
vote
0answers
64 views
Pros/cons of anonymity when messages are encrypted? [closed]
Let's say I'm making an end-to-end encrypted messaging app with the goal of putting "privacy first." The contents of messages are encrypted, but in the current model, it is still visible to the server ...
2
votes
2answers
1k views
Why the definition in $\epsilon$-differential privacy is multiplicative rather than additive？
According to its mathematical definition, a random algorithm $M: D\rightarrow R$ satisfies $\epsilon$-differential privacy if the adjacent datasets $x, y \in D$ where $D$ is a whole dataset and ...
0
votes
0answers
44 views
Audio Files and Digital Bearer Instruments
Is it possible to combine Audio Files and Public Key Cryptography creating a Digital Bearer Audio File that is in complete control of the owner who would then have the ability to grant access to ...
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vote
0answers
109 views
Private Set Intersection using a subset of the larger set
Alice has a set $S_A$ with a low cardinality (say ~30k). Bob on the other hand has a set $S_B$ with a much higher cardinality than of Alice's (say ~100M).
We're trying to create a reduced ...
0
votes
0answers
138 views
Data masking / Data obfuscation for string int float and date , preserving order and exact matches
I've to mask data into some different value but to keep their property such as order an exact match (substring is yet impossible)
What's the state of the art in data masking? I've some data on which ...
0
votes
2answers
873 views
Are there any practical use cases for performing homomorphic operations on encrypted Strings?
Does anybody know which practical use cases there are to operate on encrypted strings? Even niche problems that can be solved using homomorphic encryption on strings are interesting to me, but not ...
4
votes
1answer
315 views
What are the advantages of mutual private set intersection methods over finding the intersection of hashed lists?
I can understand the usefulness of one-way private set intersection methods. Where Alice and Bob both have listed but only Alice learns the intersection of those lists while Bob learns nothing.
I ...
-2
votes
1answer
180 views
How Zero Knowledge Proof enables Privacy By Design [closed]
How does Zero Knowledge Proof (ZKP) enable Privacy By Design?
