Cryptography Stack Exchange
Cryptography Stack Exchange

Questions tagged [data-privacy]

Data privacy refers to (cryptographic) methods to prevent the disclosure of sensitive (identifying) information of persons.

Data privacy refers to (cryptographic) methods to prevent the disclosure of sensitive (identifying) information of persons. This may either be concerned with the privacy of data itself, i.e., the content, or behavioural data of users such as how often a user uses a specific service, which services a user uses, or how often does a user access a specific data object. Former is typically achieved via encryption while for the latter a set of cryptographic privacy enhancing technologies (PETs) exist.

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Intuitive explanation of the $\varepsilon$ parameter in differential privacy

I think I have a decent intuitive understanding of what the $\delta$ parameter means in $(\varepsilon,\delta)$-differential privacy: I can explain it to a non-specialist in terms of "what are the chances that something goes horribly wrong". Even if…
Ted
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Applying machine learning algorithms to homomorphic encrypted data

I have a basic understanding of encryption and I got back to the topic because of an interesting site that encrypts financial data using homomorphic encryption (HE) and I would be happy for any input from the community here. They don't really tell…
Richi W
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Secure multiparty computation of conjunction

Suppose Alice and Bob each have bits a and b, respectively. How can Alice and Bob compute the function a and b, without revealing their bits to each other? EDIT: A paper called Solving the Dating Problem with the SENPAI Protocol came out recently.
user76284
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Is there a hash tree scheme designed for complex data structures?

I have a JSON object with private data. It has the following (complex!) structure: { name: "JB", age: 35, children: [ { name: "Alice", age: "5", favColor: "pink" }, { …
nervous-energy
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Integrity with anti-confidentiality

The Republic of Brutopia are updating the design of their library cards with a new security feature: a 2D barcode containing a cryptographically signed copy of the human-readable fields on the card. This will allow anyone to verify that a card is…
hmakholm left over Monica
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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 investigation of potential multiple account+vote abuse. In…
Inkling
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Difference between ε-differential privacy and (ε, δ)-differential privacy

I don't understand the necessity of introducing the additive term δ in the differential privacy definition. Moreover, reading different papers and blogs they say that because of the δ term the mechanism is "broken" (whatever that means). I would…
primef
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NTRU crypto from unseen.is; myth busting help

I am always on the look out for privacy enhancing technologies. I stumbled upon the service from unseen.is. I had a look at their site (specifically here) and even though I lack knowledge there are a few early warning signs: a former security…
user3244085
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Blinding an ECDSA private key without learning the private key

I am looking at ways to blind an ECDSA signing key (and verification key respectively). Looking at proposed solutions like the IETF KBSS draft, and the IETF ARKG draft it seems that the ECDSA key blinding requires a multiplicative blinding with a…
Peter Altmann
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Differential Privacy: why $\delta$ negligible on the row numbers?

The definition of differential privacy says that an algorithm $M$ is $(\epsilon,\delta)$-differentially private if $$P(M(x \in D) \in S)\leq e^\epsilon P(M(x \in D')\in S) + \delta$$ where $D,D'$ differ by one row and $\delta$ is …
volperossa
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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 'setting' of response release. What I don't get is,…
independentvariable
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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 don't understand the usefulness of two-way private…
Curious Curt
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Cryptographic scheme where a single message cannot be decrypted but if combined with other it can be

i'm wondering if this type of cryptographic scheme does exists. I know about homomorphic encryption but if one has the private key, he can decrypt every single message. I would like to know if there is a scheme where each user can encrypt the…
damianodamiano
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computational indistinguishable/distinguishable?

Let $a,b,c,d$ be selected at random from $Z_q$. Consider the following two distributions $X_1$ and $Y_1$: $X_1={(r_1\cdot a, r_2\cdot b, r_3\cdot c, (r_1+r_2-r_3)\cdot d)}$ where $r_1,r_2,r_3$ selected random from $Z_q$ $Y_1={(u_1,u_2,u_3,u_4)}$…
mohsen pourpouneh
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what does differential privacy (in machine learning) promise or guarantee?

I am recently reading some papers about privacy-preserving machine learning. Some works incorporate the idea of differential privacy to protect the privacy of the training dataset when the model is published. The basic framework is as follows: A…
Paradox
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