Questions tagged [data-privacy]

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

12
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1answer
2k views

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 ...
10
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1answer
329 views

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 ...
9
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1answer
239 views

Secure multiparty computation of conjunction

Suppose Alice and Bob each have bits a and b, respectively. How can Alice and Bob compute the function ...
7
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2answers
817 views

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. ...
6
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2answers
2k views

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 ...
4
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1answer
380 views

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 $D,D'$ ...
4
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1answer
92 views

Oblivious Transfer where neither party learns the index of the message

In a traditional Oblivious Transfer setting, the sender has a list $(x_1, x_2, ... , x_n) \in G$ where $G$ is the chosen group. The receiver has $b \in \mathbb{N}$, such that engaging in the protocol ...
4
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2answers
109 views

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 ...
4
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0answers
131 views

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 $r_1,r_2,r_3$ ...
3
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2answers
98 views

Hiding identifying data while allowing matching?

I do research with people about their illegal drug use, and for one project I'm doing surveys with them when they visit a needle exchange. So over time the same people get repeatedly surveyed as they ...
3
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1answer
697 views

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: ...
3
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1answer
216 views

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 ...
3
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1answer
144 views

Secure distance calculation

I am working on securing a feature in a csv file. My goal is to encrypt, anonymize, mask.... etc the content of the records of the feature while preserving the distance between the characters. as ...
3
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1answer
82 views

Differential privacy on multiple queries – what is the behavior?

Differential privacy framework still continue to be obscure in the following case: If I make a set of queries, I can join their output to restore the original data. For this issue we have composition ...
3
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1answer
587 views

How to enforce data privacy, integrity and authenticity of distributed firmware images for an embedded device?

I'm developing a bootloader for an embedded device, with which it should be possible for customers (i.e. device owners) to update the device's firmware. It is required that: the firmware is ...
3
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0answers
127 views

David Chaum's anonymous credential

I am a newbie in cryptography (I know the basic RSA, AES stuffs) and am interested in anonymous authentication systems. Looks like David Chaum is the godly figure in the field. I see lots of people ...
2
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2answers
277 views

Privacy and Integrity in Public Cryptography

I'm trying to figure out which is the best way to get privacy and integrity together in public cryptography. Alice needs to send multiple files $f$ (may be big) to Bob. I've thought: Alice computes ...
2
votes
1answer
372 views

Is zero IV with AES-CBC safe if CPA is not possible and indistinguishability is not an issue?

Is using zero IVs with AES-CBC safe, if chosen-plaintext attack (CPA) is not possible and ciphertext indistinguishability is not an issue? Practical example: ...
2
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1answer
69 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
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1answer
85 views

Join Datasets While Protecting Anonymity

I've run into this issue a couple of times in my career. I'll see if I can explain with an example (please ignore the fact that this is implausible in the real-world). Suppose I sell computers, and I ...
2
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0answers
69 views

End-To-End encryption for VoIP teleconference applications and many-to-many lag-sensitive applications

There are various protocols that allow you to have privacy-enhanced chat. Those can be either 2-party chat such as: OTR SIGNAL or multiparty chat such as: SIGNAL (n+1)sec mpOTR GOTR (2013 spec and ...
2
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0answers
24 views

Avoiding multiple use of sIgned identities while not learning anything about them

There is an authority A with an associated public/private key pair (A.priv, A.pub). A can issue new "identities" by signing data (numbers or bytestrings). Each number associated with a signature by A ...
2
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0answers
121 views

Merkle tree to prove integrity of subset of data

I'm thinking up a scheme where a merkle tree is used to ensure integrity of a set of data items, and different parties are allowed to verify the integrity of different subsets of that data. Let's ...
2
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1answer
123 views

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 ...
2
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1answer
43 views

Sensitivity of probability measure in differential privacy

I know that we need some sort of sensitivity(global, local) to calculate noise that needs to be added for differential privacy. The noise is the maximum difference between two neighboring datasets. ...
2
votes
0answers
198 views

Evaluate similarity between two “encrypted” time series

Can you think of any way to evaluate the similarity between two time series without revealing any information on the time series ? More precisely, considering two time series $x$ and $y$ of length ...
2
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0answers
45 views

Can I serve data for user without the ability to access them? Which functions for the user remain?

My Problem I want to serve sesible data for users as a webservice that is accessed by the user via the browser. Restrictions: I may not be able to technically acces the data of the user Data is ...
2
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0answers
352 views

CryptDB data re-encryption and onion layers

From the CryptDB paper , I understoond that the onion layers once decrypted are not re-encrypted. Only columns which are queried infrequently will be re-encrypted to higher onion layers. But if we ...
2
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0answers
182 views

Does Ciphertext policy ABE support search operation on encrypted data

Basically CP-ABE (or attribute based encryption) allows end-users to encrypt the data with desired access control structure. I was investigating the how to do keyword-search on encrypted data given ...
1
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1answer
2k views

Ensuring integrity and confidentiality together with symmetric encryption

I've been required to answer a question: As usually, we have Alice and Bob. Suppose Alice wants to send a file F to Bob, ensuring integrity and confidentiality. They share a symmetryc key $K_{...
1
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1answer
188 views

On the privacy of perfect hash functions

I'm digging into the several algorithms for building (Minimal) Perfect Hash Functions. It seems that the recent works provide quite a few very efficient algorithms. However, I'm wondering how a (M)...
1
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1answer
86 views

Disk/File modes of encryption and authentication [closed]

Secure disk/file encryption has been actively studied over the years. Beside XTS and CBC-ESSIV, are there any other modes of encryption that are commonly used? Which could be the most secure mode? ...
1
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1answer
97 views

Is the following aggregation scheme private?

Is the following scheme private? By private i mean an untrusted aggregator (UA) cannot reveal anything other then an aggregate function output on plaintext data Each party holds a secret key $k_i$ ...
1
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2answers
120 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 ...
1
vote
3answers
175 views

Encryption for IOT devices with minimal overhead

I have several IOT devices that transmits nearly 200 bytes of data every 10 seconds. I want to make the data secured but i also want to keep the data size nearly same. Ofcourse for IOT devices ...
1
vote
1answer
34 views

Divide data into parts and restore from them

I'm not much familiar with cryptography, so please guide me in the right direction on the following question: Let's say I have some data (array of bytes) $D$. I want to convert it into $N$ pieces (...
1
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1answer
273 views

Government root SSL certificate possible vulnerabilities [closed]

I'm writing an article about new government law in Kazakhstan. The law was accepted in December, but now one of our providers announced information for small and medium business how to install ...
1
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2answers
779 views

Are SSL/TLS used for maintaining data confidentiality?

In SSL/TLS, we use symmetric and asymmetric keys to encrypt the data. Does that mean that the keys are used to encrypt the data (preserve the integrity) or provide a secure channel for the data to be ...
1
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1answer
167 views

Privacy-Preserving relational databases: checking the existence of a record (or multiple records)

I would like to know if there exists a protocol which performs the following operation in a privacy-preserving fashion: User $U$ wants to know whether a record is stored in the database. The primary ...
1
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1answer
334 views

Unique, anonymous online authentication

Is there a way to authenticate users online without knowing their real identity yet preventing them from registering twice? If not, what is the least amount of information you would need? If it helps, ...
1
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1answer
46 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
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1answer
89 views

lookup encrypted text by clear text without decryption

I've implemented vouchers module in my web project where I use it to generate redeem get etc... vouchers. since voucher codes are considered sensitive, I've considered to encrypt them using AES-GCM. ...
1
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1answer
51 views

Is it possible to derive the recipient's public key from libsodium's crypto_box?

Libsodium has "crypto_box_seal" which according to the documentation is used to "anonymously send messages to a recipient given its public key.", which hides the sender. But Is it possible for Eve to ...
1
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1answer
107 views

Zero-knowledge voting with hidden weights

Assume a voting with delegates, where each delegate's vote $v_i \in \{-1,1\}$ has a certain weight $w_i$ depending on the number of people who elected the delegate. Is there a way to calculate the ...
1
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1answer
1k views

How do I safely anonymize/hash a unique identifier to protect privacy?

I am building a system to collect a unique identifier (MAC addresses from 802.11 probe requests). The system will have several collection points over a large area, submitting to a central database. I ...
1
vote
1answer
38 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 ...
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0answers
32 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 ...
1
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0answers
65 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 ...
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0answers
105 views

Laplace mechanism from Exponential mechanism in Differential Privacy

In McSherry and Talwar's paper which introduces the exponential mechanism for differential privacy, they say that the Laplace mechanism can be captured by choosing the score function as $q(d,r) = - |f(...
1
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1answer
55 views

Filter party-1 strings against party-2 white/black list keeping the lists private

Suppose I have a server and a client. The client has a list of arbitrary strings and the server is supposed to filter this list using white and black lists kept on the server side. It would be nice ...