HAL will be down for maintenance from Friday, June 10 at 4pm through Monday, June 13 at 9am. More information
Skip to Main content Skip to Navigation
Conference papers

Homomorphic-Policy Attribute-Based Key Encapsulation Mechanisms

Jérémy Chotard 1, 2, 3 Duong Phan 1 David Pointcheval 2, 3
3 CASCADE - Construction and Analysis of Systems for Confidentiality and Authenticity of Data and Entities
DI-ENS - Département d'informatique - ENS Paris, CNRS - Centre National de la Recherche Scientifique : UMR 8548, Inria de Paris
Abstract : Attribute-Based Encryption (ABE) allows to target the recipients of a message according to a policy expressed as a predicate among some attributes. Ciphertext-policy ABE schemes can choose the policy at the encryption time, contrarily to key-policy ABE schemes that specify the policy at the key generation time, for each user. In this paper, we define a new property for ABE, on top of a ciphertext-policy ABE scheme: homomorphic-policy. A combiner is able to (publicly) combine ciphertexts under different policies into a ciphertext under a combined policy (AND or OR). This allows to specify even much later the policy for a specific ciphertext: the sender encrypts, and the combiner specifies the policy, without knowing the plaintext. More precisely, using linear secret sharing schemes (LSSS), we design Attribute-Based Key Encapsulation Mechanisms (ABKEM) with our new Homomorphic-Policy property. Technically, by exploiting a specific property in the structure of LSSS matrix, we can show that, given several en-capsulations of the same keys under various policies, anyone can derive an encapsulation of the same key under any combination of the policies. As a consequence, from encapsulations under many single attributes, one can build an encapsulation under a complex policy over the attributes. Similarly to the case of encryption with homomorphic properties, where malleability weakens confidentiality, homomorphic-policy ABE also weakens the security of an ABE when the combiner colludes with legitimate users. On the other hand, homomorphic-policy provides additional flexibility and nice features when one targets some practical application: in Pay-TV, this allows to separate the content providers that can generate the encapsulations of a session key under every attributes, this key being used to encrypt the payload, and the service providers that build the decryption policies according to the subscriptions. The advantage is that the aggregation of the encapsulations by the service providers does not contain any secret information.
Document type :
Conference papers
Complete list of metadata

Cited literature [18 references]  Display  Hide  Download

Contributor : Jérémy Chotard Connect in order to contact the contributor
Submitted on : Tuesday, October 3, 2017 - 2:26:37 PM
Last modification on : Thursday, March 17, 2022 - 10:08:53 AM


Homomorphic policy attribute b...
Files produced by the author(s)




Jérémy Chotard, Duong Phan, David Pointcheval. Homomorphic-Policy Attribute-Based Key Encapsulation Mechanisms. 20th International Conference on Information Security (ISC '17), Nov 2017, Ho Chi Minh, Vietnam. ⟨10.1007/978-3-319-69659-1_9⟩. ⟨hal-01609278⟩



Record views


Files downloads