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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1answer
34k views

What is Attribute Based Encryption?

Can someone explain what attribute based encryption is? I was searching for a book or something that can help me in this regard but so far I have found none. Google also returns practically nothing ...
10
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1answer
200 views

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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280 views

What are the current limitations (and capabilities) of Functional Encryption used for access control?

I'm trying to make my way in Functional Encryption used for access control. I read a lot of papers such as "How to Run Turing Machines on Encrypted Data", "Functional Encryption: New Perspectives and ...
7
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3answers
1k views

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 ...
7
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298 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 ...
6
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1answer
308 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 ...
4
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3answers
111 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 ...
4
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2answers
4k views

What are monotonic and non monotonic access structures in ABE ?

While reading Attribute Based Encryption Schemes, I did not quite understand what a monotonic access structure or non monotonic access structures are. Is there a popular explanation of those terms ? ...
4
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1answer
240 views

How is the ciphertext labeled with a set of attributes in Key-Policy Attribute-based Encryption (KP-ABE)

My question is about Key-Policy ABE (KP-ABE). What does it mean when a "Ciphertext is Labeled with set of attribute"? How is it labeled?
4
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1answer
121 views

Can we run a probabilistic function on ciphertext with Functional Encryption (or Attribute Based Encryption)?

In the definition of functional encryption ($FE$): $FE.Setup(1^k)$ takes as input the security parameter $1^k$ and outputs a master public key $fmpk$ and a master secret key $fmsk$. $FE.KeyGen(fmsk, ...
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2answers
689 views

What is “msg = group.random(GT)” in Charm encryption schemes?

In many encryption schemes in Charm the random group message is used instead of a text-message: msg = group.random(GT) For example, in CP-ABE scheme, random ...
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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? ...
3
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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 ...
3
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1answer
65 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 ...
3
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1answer
113 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 ...
3
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2answers
223 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. ...
3
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1answer
315 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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167 views

User revocation in Identity Based Encryption

I read several papers about user revocation in IBE recently. A common point is that when a user is revoked, some other valid users should also update their private keys. Does this mean that one ...
2
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1answer
407 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:...
2
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2answers
411 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 ...
2
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1answer
2k views

ABE Schemes - Access Structures & Performance

I'm reading this article, CP-ABE with constant-size keys for lightweight devices and in the Table 1, are there these access structure: Threshold, Tree, ($n$,$n$)-Threshold, LSSS, AND gates. I have 2 ...
2
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2answers
54 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 ...
2
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1answer
258 views

What is the relationship between attribute based encryption (ABE) and access control?

So if possible could someone tell me or at least recommend a book.
2
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2answers
256 views

Hierarchical access control using CP-ABE

Is it possible to use CP-ABE to provide a layered (hierarchical) organization? For example, If I have 100 records, I will encrypt the first 10 records (lowest level) to be decrypted using certain ...
2
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2answers
413 views

Attribute-based encryption for cloud storage

I'm trying to understand attribute-based encryption schemes. Almost all articles describe that they are designed for cloud storage, but as I understand, almost all computing (encryption & ...
2
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1answer
2k views

what is the difference between IBE and ABE schemes

Can somebody explain in simple words. real life example light help and limitations of these schemes etc.
2
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1answer
129 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)?
2
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1answer
287 views

Attribute-based broadcast encryption with respect to ABE

What is the exact difference between attribute-based encryption (ABE) and attribute-based broadcast encryption (ABBE)? Is ABBE equivalent to broadcast encryption on top of ABE?
2
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1answer
181 views

Simplification of a pairing

The paper Expressive, Efficient, and Revocable Data Access Control for Multi-Authority Cloud Storage contains the following simplification: $$e(C_i,\text{GPK}_{uid})\cdot e(D_i, K_{\rho(i),uid})\...
2
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1answer
68 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 ?
2
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0answers
103 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 ...
2
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0answers
79 views

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 ...
2
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0answers
115 views

Access structure in Attributes Based Encryption [duplicate]

I thought that access structure and access tree are equivalent but I've read in a paper (page 3) that there are at least three types of access structures : AND gates Access tree LSSS generating ...
2
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0answers
158 views

Attribute Based Encryption [duplicate]

Could someone explain the main differences between Key Policy Attribute Based Encryption (KP-ABE) and Ciphertext Policy Attribute Based Encryption using an example? I know that KP-ABE depends on the ...
2
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0answers
307 views

CP-ABE: structure of the secret key SK

I am working on Ciphertext-Policy Attribute based Encryption (CP-ABE) and I need to understand how a secret key looks like. For example, assume that the universe of attributes is defined to be {A,B,C,...
2
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0answers
185 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 ...
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1answer
158 views

Do I need to prove this?

I am using ABE scheme that has already proven under BDHE assumption. Here is the scheme https://eprint.iacr.org/2008/290.pdf In the key generation algorithm, I want to tie the user secret key ...
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1answer
654 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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1answer
327 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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1answer
161 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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1answer
199 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 ...
1
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2answers
525 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 ...
1
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1answer
308 views

cp-abe public key, access structure

I have three questions regarding CP-ABE: 1) Is it correct to assume that in this scheme there is only one public key? Private keys are generated based on one's attributes that I do understand, by the ...
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1answer
82 views

What does this advantage statement signify?

In many Attribute Based Encryption papers I see this line... The advantage of an adversary A in this game is defined as Pr[b' = b] − 1/2. Can someone explain what it means to me? I assume it means ...
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1answer
189 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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1answer
380 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
380 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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1answer
244 views

Composite vs Prime Order Groups in Attribute Based Encryption

Reading about Accountability in ABE currently and the paper "White-box traceable ciphertext-policy attribute-based encryption supporting flexible attributes" when comparing its system with an existing ...
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1answer
417 views

How to calculate secret key size of a CP-ABE scheme

How can I calculate the real size of key in a CP-ABE scheme. For example, I have this GSWV scheme: Fuchun Guo, Willy Susilo, Duncan Wong, Vijay Varadharajan: CP-ABE with constant-size keys for ...
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1answer
118 views

Exponent operation over element of G

I found a definition of an exponent operation over the element of $\mathbb{G}$ in this paper (page 4): $$ (g^a)^{\% b} = g ^{a \text{ mod } b}$$ I couldn't understand the rest of the paper (Decrypt ...