Cryptology ePrint Archive: Report 2010/035
Between Hashed DH and Computational DH: Compact Encryption from Weaker Assumption
Goichiro Hanaoka and Kaoru Kurosawa
Abstract: In this paper, we introduce
the intermediate hashed Diffie-Hellman (IHDH) assumption
which is weaker than the hashed DH (HDH) assumption (and thus the decisional DH
and is stronger than the computational DH assumption.
We then present two public key encryption schemes with short ciphertexts
which are both chosen-ciphertext secure under this assumption.
The short-message scheme has smaller size of ciphertexts
than Kurosawa-Desmedt (KD) scheme,
the long-message scheme is a KD-size scheme with arbitrary plaintext length
which is based on a weaker assumption
than the HDH assumption.
Category / Keywords: public-key cryptography /
Date: received 22 Jan 2010
Contact author: hanaoka-goichiro at aist go jp
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Version: 20100126:043333 (All versions of this report)
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