Cryptology ePrint Archive: Report 2012/500

Constant Ciphertext Length in CP-ABE

Nishant Doshi and Devesh Jinwala

Abstract: Ciphertext policy attribute based encryption (CP-ABE) is a technique in which user with secret key containing attributes, only able to decrypt the message if the attributes in the policy match with the attributes in secret key. The existing methods that use reasonably computable decryption policies produce the ciphertext of size at least linearly varying with the number of attributes with additional pairing operations during encryption and decryption. In this paper, we propose a scheme in which ciphertext remains constant in length, irrespective of the number of attributes. Our scheme works for a threshold case: the number of attributes in a policy must be a subset of attributes in a secret key. The security of propose scheme is based on Decisional Bilinear Diffie-Hellman (DBDH) problem.

Category / Keywords: public-key cryptography / Attribute, Attribute based encryption, ciphertext policy, constant ciphertext length

Date: received 29 Aug 2012

Contact author: doshinikki2004 at gmail com

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Version: 20120903:130121 (All versions of this report)

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