## Cryptology ePrint Archive: Report 2007/133

New Communication-Efficient Oblivious Transfer Protocols Based on Pairings

Helger Lipmaa

Abstract: We construct two simple families of two-message $(n,1)$-oblivious transfer protocols based on degree-$t$ homomorphic cryptosystems with the communication of respectively $1+\lceil n/t \rceil$ and $3+\lceil n/(t+1) \rceil$ ciphertexts. The construction of both families relies on efficient cryptocomputable conditional disclosure of secret protocols; the way this is done may be of independent interest. The currently most interesting case $t=2$ can be based on the Boneh-Goh-Nissim cryptosystem. As an important application, we show how to reduce the communication of virtually any existing oblivious transfer protocols by proposing a new related communication-efficient generic transformation from computationally-private information retrieval protocols to oblivious transfer protocols.

Category / Keywords: cryptographic protocols/Conditional disclosure of secrets, homomorphic encryption, oblivious transfer

Publication Info: Accepted to ISC 2008

Date: received 17 Apr 2007, last revised 19 Jun 2008

Contact author: h lipmaa at cs ucl ac uk

Available format(s): PDF | BibTeX Citation

Note: Changes are only decorative compared to July 2007 version.

Short URL: ia.cr/2007/133

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