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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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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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24 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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26 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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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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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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24 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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161 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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73 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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107 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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46 views

Funtional encryption to Attribute based encryption

I have been reading through the literature in Functional encryption and Attribute based encryption. Undoubtedly, FE is a stronger notion than ABE and FE implies ABE. But, to my knowledge till now I ...
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77 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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58 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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33 views

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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127 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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193 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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80 views

What is the difference DET-ABE Vs CP-ABE and KP-ABE?

I can't understand what's does it mean DET-ABE (digital envelope technique ) exactly , and is there a difference between it and the the cipher or key policy attribute based encryption, could someone ...
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113 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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87 views

How to express access structure (access tree, linear secret sharing, etc.)

What are the differences and similarities between access trees (binary decision diagrams) and linear secret sharing in the use of attribute-based encryption schemes for access control?
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2answers
266 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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57 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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274 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
197 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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125 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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143 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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188 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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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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176 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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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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91 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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306 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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93 views

Access Policy Representation in Constant-Size Ciphertext Policy Attribute based Encryption (CP-ABE) Scheme

I am reading the paper "Efficient Privacy-Preserving Ciphertext-Policy Attribute Based-Encryption and Broadcast Encryption" CP_ABE. I am unable to understand how the access policy is represented and ...
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62 views

Non-trivial access structures

I am currently working with this paper about a searchable encryption scheme where access to search operations is restricted via monotone access structures and sets of attributes. In the definition of ...
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162 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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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
117 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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69 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 ...
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90 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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188 views

Ciphertext attribute-based encryption complexities and performance

I am trying to analyze the performance of the Bethencourt CP-ABE (Ciphertext-Policy based, Attribute Based Encryption) scheme. Assume $e: G_0 \times G_0 \rightarrow G_T$ is a bilinear map where $G_0$...
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260 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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CP-ABE Pairing method

Can anyone kindly provide an example on "How to generate keys by using those Bi linear mapping". First of all I chose a group generator of g=7 and an order of p=13. Therefore I got the group G0={1…12}....
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1answer
94 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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121 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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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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How Cipher text policy Attribute based encryption use in practically? [duplicate]

Firstly I am confused in CPABE, that is the receiver party should know at-least satisfying attribute(authorized sets) so that it should matches with access structure corresponds with Cipher-text, then ...
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202 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
333 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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CP-ABE based signcryption and the universe of parameters

I am researching the subject of signcryption, I'm especially intersted by models related to CP-ABE. I came by the two following works: work1 work2 Do these system require specifying all of the '...
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251 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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200 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. ...