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Variants of waters’ dual system primitives using asymmetric pairings

Ramanna, Somindu C and Chatterjee, Sanjit and Sarkar, Palash (2012) Variants of waters’ dual system primitives using asymmetric pairings. In: Proceedings of the 15th International Conference on Practice and Theory in Public Key Cryptography, May 21-23, 2012, Darmstadt, Germany.

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Official URL: http://dx.doi.org/10.1007/978-3-642-30057-8_18


Waters, in 2009, introduced an important technique, called dual system encryption, to construct identity-based encryption (IBE) and related schemes. The resulting IBE scheme was described in the setting of symmetric pairing. A key feature of the construction is the presence of random tags in the ciphertext and decryption key. Later work by Lewko and Waters removed the tags and proceeding through composite-order pairings led to a more efficient dual system IBE scheme using asymmetric pairings whose security is based on non-standard but static assumptions. In this work, we have systematically simplified Waters 2009 IBE scheme in the setting of asymmetric pairing. The simplifications retain tags used in the original description. This leads to several variants, the first one of which is based on standard assumptions and in comparison to Waters’ original scheme reduces ciphertexts and keys by two elements each. Going through several stages of simplifications, we finally obtain a simple scheme whose security can be based on two standard assumptions and a natural and minimal extension of the decision Diffie-Hellman problem for asymmetric pairing groups. The scheme itself is also minimal in the sense that apart from the tags, both encryption and key generation use exactly one randomiser each. This final scheme is more efficient than both the previous dual system IBE scheme in the asymmetric setting due to Lewko and Waters and the more recent dual system IBE scheme due to Lewko. We extend the IBE scheme to hierarchical IBE (HIBE) and broadcast encryption (BE) schemes. Both primitives are secure in their respective full models and have better efficiencies compared to previously known schemes offering the same level and type of security.

Item Type: Conference Paper
Additional Information: Copyright of this article belongs to IEEE.
Keywords: Identity-Based Encryption; Dual System Encryption; Asymmetric Pairing
Department/Centre: Division of Electrical Sciences > Computer Science & Automation
Depositing User: Francis Jayakanth
Date Deposited: 26 Nov 2013 15:30
Last Modified: 26 Nov 2013 15:37
URI: http://eprints.iisc.ac.in/id/eprint/47823

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