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Questions tagged [abe]

Attribute-Based Encryption is a type of public-key encryption in which the key used for encryption is based on selected attributes of the readers. Decryption of the ciphertext is possible only if the set of attributes of the user includes all the attributes used to encrypt the ciphertext.

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Performance evaluation in terms of Boolean operations

How can I conduct a performance evaluation in terms of Boolean operations for an access policy which supports them? Could someone explain this to me in simple terms or suggest some specific reading?
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Performance evaluation of Boolean operations

How can i conduct performance evaluation in terms of Boolean operations for Access policy which support Boolean operations? Could some one explain this to me in simple terms or suggesting some papers ...
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100 views

Adaptive vs. Static security model in ABE

From Lewko, I understand the difference between an adaptive and selective model: Adaptive model: the attacker can adaptively query the challenger for private keys. Selective model: the attacker has ...
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40 views

Problem in generation of keys in KP-ABE

In KP-ABE the owner encrypts the message using attributes say a'. The Attribute authority(AA) designs an access structure and implants that access structure in keys generated by AA for the user. So, ...
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61 views

Can anyone elaborate why KP-ABE is better than CP-ABE for television program broadcasting?

I know the difference between KP-ABE and CP-ABE. I am not able to understand why KP-ABE is better for broadcasting than CP-ABE ?
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21 views

Setup phase in Ciphertext-Policy Attribute-Based Encryption

I am having hard time understanding the setup phase in Ciphertext-Policy Attribute-Based Encryption. What is the role of each parameter?
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33 views

Proxy decrypt algorithm in Extended Proxy-Assisted Attribute Based Encryption (ABE) Scheme

Context I'm trying to implement the Attribute-Based Encryption (ABE) scheme described in the paper - Extended Proxy-Assisted Approach: Achieving Revocable Fine-Grained Encryption of Cloud Data (Yang ...
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28 views

How the ciphertext generated within a CP-ABE scheme is structured?

In ciphertext policy attribute based encryption 1 we use a tree structure with different keys into order to access attributes and the attributes are embedded to the ciphertext. Could you please let ...
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50 views

Correctness Proof in “A tree-based CP-ABE scheme with hidden policy … ”

I could not understand one step in correctness proof of paper titled "A tree-based CP-ABE scheme with hidden policy supporting secure data sharing in cloud computing" authored by Runhua Xu, Yang Wang,...
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40 views

Are attributes of an access structure visible or guessable in a CP-ABE ciphertext?

Suppose that Alice has attributes A, B and C. I have a ciphertext with this policy: A AND C. Can an adversary guess the attributes and then decrypt the ciphertext? What is the probability of ...
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30 views

scenario for KP-ABE in which it fits better than CP-ABE

I know the difference between KP-ABE and CP-ABE.What can be a scenario in which KP-ABE fits better than CP-ABE?
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DecryptNode for non-leaf Node in CP-ABE

I've looked at paper Ciphertext-Policy Attribute-Based Encryption by Bethencourt, Sahai, Waters and see this an answer here for the explanation of DecrypNode for a ...
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1answer
171 views

the decryptNode function for leaf nodes in CP-ABE

Can someone please explain to me why decryptNode gives as result $e(g,g)^rq(0)$ for leaf nodes, I don't understand how they went from the second step to the third (here is the article: Ciphertext-...
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313 views

CP-ABE for threshold cryptography

I would like to know if there is any research work using CP-ABE for threshold cryptography? I want to know also if applying CP-ABE for threshold cryptography would overcome other techniques.
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What is the motivation behind Key-policy Attribute-based Encryption?

What is Attribute Based Encryption? has a nice explanation what both forms (Ciphertext-policy Attribute-based Encryption and Key-policy Attribute-based Encryption) are. My question is: what is the ...
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2answers
217 views

Can the access policies defined using different access structures (Monotone Span Program and Access Trees) be used together in CP-ABE scheme?

In order to add authentication features to this CP-ABE scheme, I have tried to combine it with the ABS scheme proposed by Maji et. al. I want to use the sign() and verify() algorithms of ABS scheme. ...
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1answer
131 views

ABE (attribute based encryption) vs ABS (attribute based signature)

I want to know if there is any shortcoming that ABE cannot achieve and that the ABS complete it. I mean why the ABS is included if the authentication and the authorization are already ensured by the ...
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109 views

Scheme that encrypt with $n$ pk that any sk of the pks can decrypt?

Suppose there are $n$ users each with public/private key pair $(pk_i,sk_i)$ $i=1,\cdots,n$. Is there any scheme that I can encrypt $m$ using the set of public keys $(pk_1,\cdots,pk_n)$, and can ...
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1answer
170 views

Access tree and Key geneation in KP-ABE

I tried for about 1 month to understand ABE and know I am confusing about access tree. In paper "Attributed-based encryption for fine-grained access control of encrypted data" the author explained the ...
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1answer
105 views

derive child keys from a private key

My problem is the following: I have an organization with many members. When someone from the outside communicates with this organization, I want any member to be able to decrypt the communication. ...
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Why only ABE is used in ABAC

Why ABAC access control model uses ABE not RSA or any other public key cryptography? Moreover what is the relation of ABAC with public key cryptography (ABE/RSA)?
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What are general circuits exactly?

This may be a silly question but while reading this paper Circuit ABE from LWE, I came across this question on 2nd page - Is there an ABE scheme for general circuits with unbounded attribute length ...
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283 views

Security proof in (Ciphertext-Policy) Attribute-Based Encryption

I am having hard time understanding the security proof in Attribute-Based Encryption, especially in Ciphertext-Policy Attribute-Based Encryption. To do reduction in CP-ABE scheme, how do I check that ...
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1answer
279 views

multiplication of two points belong to elliptic curve

I have a question about multiplication of two points belong to elliptic curve. I know every think about adding and scalar multiplication but not about multiplication of two points. Is there any method ...
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403 views

I cannot understand the concept of a divisor for an elliptic curve

I am trying to understand ABE for a project of mine. I've grasped the concept of elliptic curves, but could not understand the meaning of divisors for functions on them. Could anyone help me with ...
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1answer
60 views

Enabling Oblivious Access Control via Function Encryption

Abstract With Functional Encryption, would access control between two parties be possible without revealing the entirety of one party's policy to the other? E.g. such that a server would be incapable ...
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349 views

Attribute Authentication in Attribute Based Encryption (ABE)

When a data user requires access it asks the key issuer to generate a key for it using the specified attributes. How does the key issuer authenticate that the data user actually acquires the ...
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200 views

What cryptographic protocol or algorithm I can use to encrypt/decrypt a subset of columns of a database table for each user?

What cryptographic protocol or algorithm I can use to encrypt/decrypt a subset of columns of a database table for each user? For example say I have a database table with 50 columns ...
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1answer
11k views

Simple example for CP-ABE (Ciphertext policy attribute-based encryption)

I'm currently working on Ciphertext Policy Attribute-Based Encryption (CP-ABE). So far I'm only using it with a basic understanding how it actually works. Now I want to understand it a bit better, but ...
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3answers
128 views

How to encrypt a message such when a certain condition is met it can be decrypted?

Assume, there is a certificate authority whose public key: $pk$, is known. Also, the certificate $c$ is known, but not the signed certificate. I want to encrypt a message: $m$, such that whoever has ...
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1answer
720 views

Multi Authority Attribute Based Encryption Library

Anyone aware of a library that has MA-ABE implemented in any language preferably python? P/S - I hope this is the right place to ask this. Apologies if not, then a redirect will be appreciated
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152 views

About numberical comparison in Attribute based encryption

The first CP-ABE scheme in [BSW07] gave an example how to present a numberical comparison (e.g., a<11) to a Boolean access tree. But it seems like this feature is not implemented in Charm. In the ...
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202 views

What is the key size and security level of attribute-based encryption schemes?

I am studying the ABE for my masters theses however I want to calculate the key and it's strength. I have done a research about the KP-ABE and I want to know the size of the key and how to determine ...
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1answer
398 views

Pairings in Identity-based encryption vs. Attribute-based encryption

The bilinear map in Identity-based encryption should satisfy $e(aP,bQ)=e(P,Q)^{a\cdot b}$ whereas Attribute-based encryption schemes use $e(P^a,Q^a)=e(P,Q)^{a\cdot b}$ with $a,b\in\mathbb{Z}_p$ and $e:...
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1answer
635 views

Setting up of polynomials for CP-ABE or KP-ABE Access Trees

My question I guess is how the selection is done. A brief explanation with a simple access tree will be very helpful.
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298 views

What paradigm does ABE, KP-ABE and CP-ABE fall into

Do attribute-base encryption (abe), key policy attribute-based encryption (KP-ABE) and ciphertext attribute-based encryption (CP-ABE) fall into the attribute-based access control (ABAC) paradigm or ...
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88 views

Certificate Master Public Key with Pairing

I am currently working on CipherText Policy Attribute Based Encryption (CP-ABE) scheme. If we see the scheme, we can notice that the Authority may generate a Master Public Key and a Master Private Key(...
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Are pairings still the most efficient implementation for identity and attribute-based encryption?

I read on Wikipedia: [...] pairings have also been used to construct many cryptographic systems for which no other efficient implementation is known, such as identity based encryption or attribute ...
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if ABE scheme based on RSA generate constant secret key will get better resutls than schemes based on Elliptic curve?

We know in term of security level, ECC key is stronger than RSA , 160 bit ECC equivalent to 1024 bit key in RSA. If I can generate constant secret key based on RSA is that mean my scheme performance ...
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102 views

Why does the DBDH simulator have half the advantage of an adversary?

Literature that includes the DBDH assumption such as this paper or this paper has a formal security proof that states: Suppose an adversary with non-negligible advantage $\varepsilon = Adv$. A ...
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364 views

Which Attribute Based Encryption method is better for broadcast encryption? (KP-ABE or CP-ABE)

I have a basic understanding of public-private and symmetric crypto, but I keep struggling with the concept of ABE. I know the difference between the two variants: Key-Policy: A key is linked to a ...
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1answer
121 views

What cipher(s) can or should I use for attribute based encryption?

What cipher(s) can or should I use for attribute based encryption? Can I use AES for that, or should I use some other, specific cipher(s)?
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1answer
106 views

Calculating CP-ABE random secret $s$ initialized by the data owner

I am analyzing the Bethencourt CP-ABE model to understand the math behind it. If a data user is able to satisfy the access policy attached to the ciphertext, that user is able to decrypt the encrypted ...
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1answer
377 views

Is it feasible to use combination of ABE schemes for encrypting the data?

I have a peculiar requirement for preserving the shared log files. For example I have 1000 records which belong to different organizations as listed below and all the logs are present in a single CSV ...
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1answer
185 views

How can I plot graphs of CP-ABE scheme using charm crypto?

Can I use charm crypto tool to run it over my datasets for CPABE scheme and plot graphs using its Benchmarking tool ? Or, how can I use Charm Crypto tool with CPABE toolkit ?
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171 views

How are attributes encoded in private keys in Attribute-Based Encryption?

I understand how private keys are generated from public keys in a setup like Bitcoin (using ECDSA). I understand that anyone can verify they have the 'correct' private key using a digital signature ...
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1answer
366 views

CP-ABE Key generation random parameters

In the key generation algorithm of cp-abe there are attributes: $x_1, x_2,...x_n \in \{0,1\}^*$ $r, r_{x_1}, r_{x_2},...r_{x_n} \xleftarrow{R} Z_p$ are chosen randomly to generate the private key $...
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What's the meaning of “Ops” in this ABE schemes performance form

I am a Ph.D. student focus on Attribute-Based Encryption and now reading the paper "Outsourcing the Decryption of ABE Ciphertexts", about the Figure 1, it gives a summary of some ABE scheme ...
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2answers
1k views

Why was there a need to create CP-ABE when KP-ABE already exist?

This is more of a good to know question, but looking online and in this forum I couldn't find an answer to this question. Was there some major reason why CP-ABE was created when KP-ABE already exist? ...