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
45 views

I don't understand the definition of monotonic access structures

I am very confused with definition 1 in section 2.1 of this article. Definition 1 (Access Structure [2]) Let $\left\{ P_1, P_2, ..., P_n \right\}$ be a set of parties. A collection $\mathbb{A} \...
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CP-ABE (Bethencourt): How KeyGen computes $D=g^{(\alpha+r)/\beta}$?

I have one doubt from CP-ABE KeyGen algorithm (paper). In Setup, master key is $MK=(\beta, g^\alpha)$. In KeyGen(MK, S), they say generate random number $r$ and compute $D=g^{(\alpha+r)/\beta}$. ...
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Regarding expansion of one equation in “Attribute based signature and its applications”

This is regarding one equation in paper titled "Attribute based signature and its applications" by Jin Li. Link: https://dl.acm.org/doi/10.1145/1755688.1755697 Can somebody help me in understanding ...
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89 views

What is the difference between $\in$ and $\in_{\small R}$?

I have a simple question about basic math. When I read different papers bout ABE, I see different methods to choose a random exponent. What is the difference between the following options? Choose a ...
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1answer
71 views

Is hybrid encryption required to use Attribute based Encryption to encrypt messages?

Does the mechanism behind Attribute Based Encryption require us to first encrypt the message by using a symmetric cipher, e.g. AES, and then encrypt the AES key by using Attribute Based Encryption? ...
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40 views

Is attribute-based encryption used to encrypt data and apply access control, or only do the latter?

I am trying to decide whether to encrypt data by using attribute-based encryption or use an encryption algorithm such as AES before using attribute-based encryption. Is attribute-based encryption ...
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41 views

CP-ABE implementation in cpabe toolkit

I have designed a CP-ABE scheme which is different from original scheme by bethencourt. Now the cp-abe toolkit supports the original scheme and in order to use the toolkit for my scheme I have to ...
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24 views

Does it make sense to try CP-ABE in a database for a individual database records?

I'm almost ready for my graduation research project, and I'm looking for an interesting crypto-related topic. I came across CP-ABE, and since I'm working in infosec it caught my attention. Will it ...
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1answer
118 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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49 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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2answers
93 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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75 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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61 views

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
342 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.
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169 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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120 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
230 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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103 views

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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1answer
306 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
601 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
265 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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901 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
76 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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2answers
522 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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1answer
217 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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3answers
142 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
186 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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213 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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101 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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218 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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92 views

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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116 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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514 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
241 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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197 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
136 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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95 views

What's the meaning of “Ops” in this ABE schemes performance form?

I am a Ph.D. student focusing on Attribute-Based Encryption, and now I'm reading the paper "Outsourcing the Decryption of ABE Ciphertexts", seen in Figure 1 below. It gives a summary of an ABE scheme ...
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102 views

Chosen plain-text attack proof for Bethencourt CP-ABE scheme

Consider the CPA security game which consists of the following steps: Initialization Setup Phase 1 Challenge Phase 2 Guess Can someone provide the proof for this game under Bethencourt ...
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1answer
363 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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1answer
129 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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149 views

ABE Cryptography - Send user private key

I am studying Attribute Based Encryption. Now my study concerns CP-ABE scheme. The authority make users private keys using attributes and a Master Secret Key (of Authority). How can the authority send ...
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2answers
2k 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? ...
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2answers
286 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 ...
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1answer
415 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
360 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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2answers
283 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
160 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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322 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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258 views

Security Proof in Fuzzy Identity Based Encryption?

Been having a great deal of difficulty understanding the use of simulators to prove security of ABE schemes so I though I would start from the first ABE paper (Fuzzy Identity Based Encryption) to try ...