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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What is the meaning of the power notation in the access structure?

In the paper about ABE (like this), the access structure is defined as follow: Let ${P_1,P_2,...,P_n}$ be a set of parties. A collection $A⊆2^{\{P_1,P_2,...,P_n\}}$ is monotone if $∀B,C$: if $B∈A$ ...
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Combining CP-ABE and KP-ABE by wrapping one with the other?

I've looked around but can't find any discussion on using both CP-ABE and KP-ABE by simply wrapping one with the other. It seems like you'd be able to get more fine grained access control with a ...
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KP-ABE Key Generation

In Key Policy Attribute-based encryption if we need a targeted broadcast where the set of attributes are the same for a group of users. It means they all share the same secret key right? Or is it that ...
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IBE for Access Control

What makes IBE (Identity-based Encryption) unsuitable for Access Based mechanisms? What are the attempts made for using IBE for access control? How does the concept of ABE (Attribute-Based Encryption) ...
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KP-ABE Comparison with CP-ABE

Why is it that designing CP-ABE(ciphertext policy) schemes is preferred over KP-ABE (key policy)? The recent developments/research seems to be focussing on CP-ABE more than KP-ABE. What are the issues ...
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Adaptive Security Advantage

Adaptive model: the attacker can adaptively query the challenger for private keys. The challenge message need not be revealed at the start of the security game Selective model: the attacker has to ...
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Developments in ABE using Pairings

What are the recent developments in Attribute-Based Encryption (ABE) using Pairings assumptions? Is pairings the most viable assumption while designing ABE. What other assumptions are used for ABE ...
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What are access structures in Attribute-Based Encryption?

I'm reading this article, but I could'nt figure out Definition 1 (Access Structure) on page 3, section 3.1. It says: Let $\{P_1, P_2,...,P_n\}$ be a set of parties. A collection $\mathbb{A} \subseteq ...
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How to find the co-efficients of a function within Zp[x]?

I am a newbie in Finite Field arithmetic and while trying to implement an Elliptic Curve Cryptography based ABE scheme in a programming language, I am unable to understand how to implement function ...
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I wanted to know the size of plaintext, key and ciphertext of the KP-ABE algorithm

I have to present an ieee paper at my college, and I picked up a topic based on KP-ABE encryption and the paper doesn't have the size of plaintext, key and ciphertext in it
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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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 a ...
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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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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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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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Will the ABE scheme based on RSA generate a constant secret key better than schemes based on elliptic curve cryptography?

We know in terms of security level, that an ECC key is stronger than an RSA one (e.g. a 160-bit ECC key would be equivalent to a 1024-bit key in RSA). If I can generate a constant secret key based on ...
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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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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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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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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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2 votes
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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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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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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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6 votes
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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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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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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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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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