EFFICIENT CONDITIONAL PROXY RE ENCRYPTION WITH CHOSEN CIPHER TEXT SECURITY

Article:

EFFICIENT CONDITIONAL PROXY RE ENCRYPTION WITH CHOSEN CIPHER TEXT SECURITY

Abstract:

In a proxy re-encryption (PRE) scheme, Alice gives a special information to a proxy that allows it to transform messages encrypted under Alice's public key into a encryption under Bob's public key such that the message is not revealed to the proxy. In [14], Jian Weng and others introduced the notion of conditional proxy re-encryption (C-PRE) with bilinear pairings. Later, a break for the same was published in [17] and a new C-PRE scheme with bilinear pairings was introduced. In C-PRE,  the proxy also needs to have the right condition key to transform the ciphertext (associated with a condition set by Alice) under Alice's public key into ciphertext  under Bob's public key, so that Bob can decrypt it. In this paper, we propose an efficient C-PRE scheme which uses substantially less number of bilinear pairings when compared to the existing one [17]. We then prove its chosen-ciphertext security under modified Computational Diffie-Hellman (mCDH) and modified Computational Bilinear Diffie-Hellman (mCBDH) assumptions in the random oracle model. 

Keywords:

Random Oracle Model, Proxy Re-Cryptography, Conditional Proxy Re-encryption, Chosen Ciphertext Security.

Original Source URL: http://airccse.org/journal/nsa/0312nsa14.pdf

http://airccse.org/journal/jnsa12_current.html