Cryptology ePrint Archive: Report 2013/646

Direct Chosen-Ciphertext Secure Attribute-Based Key Encapsulations without Random Oracles

Johannes Blömer and Gennadij Liske

Abstract: We present a new technique to realize attribute-based encryption (ABE) schemes secure in the standard model against chosen-ciphertext attacks (CCA-secure). Our approach is to extend certain concrete chosen-plaintext secure (CPA-secure) ABE schemes to achieve more efficient constructions than the known generic constructions of CCA-secure ABE schemes. We restrict ourselves to the construction of attribute-based key encapsulation mechanisms (KEMs) and present two concrete CCA-secure schemes: a key-policy attribute-based KEM that is based on Goyal's key-policy ABE and a ciphertext-policy attribute-based KEM that is based on Waters' ciphertext-policy ABE. To achieve our goals, we use an appropriate hash function and need to extend the public parameters and the ciphertexts of the underlying CPA-secure encryption schemes only by a single group element. Moreover, we use the same hardness assumptions as the underlying CPA-secure encryption schemes.

Category / Keywords: public-key cryptography / attribute-based key encapsulation mechanism, attribute-based encryption, chosen-ciphertext security, bilinear maps

Date: received 8 Oct 2013

Contact author: gennadij liske at upb de

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Version: 20131010:151645 (All versions of this report)

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