**Realizing Chosen Ciphertext Security Generically in Attribute-Based Encryption and Predicate Encryption**

*Venkata Koppula and Brent Waters*

**Abstract: **We provide generic and black box transformations from any chosen plaintext secure Attribute-Based Encryption (ABE) or One-sided Predicate Encryption system into a chosen ciphertext secure system.
Our transformation requires only the IND-CPA security of the original ABE scheme coupled with a pseudorandom generator (PRG) with a special security property.

In particular, we consider a PRG with an $n$ bit input $s \in {0,1}^n$ and $n\cdot \ell$ bit output $y_1, ..., y_n$ where each $y_i$ is an $\ell$ bit string. Then for a randomly chosen $s$ the following two distributions should be computationally indistinguishable. In the first distribution $r_{i,s_i} = y_i$ and $r_{i, \bar{s}_i}$ is chosen randomly for $i \in [n]$. In the second distribution all $r_{i,b}$ are chosen randomly for $i \in [n], b \in {0,1}$.

**Category / Keywords: **

**Date: **received 7 Sep 2018, last revised 14 Sep 2018

**Contact author: **k venkata vk at gmail com

**Available format(s): **PDF | BibTeX Citation

**Note: **Added text on simple argument for hinting PRG separation.

**Version: **20180914:220147 (All versions of this report)

**Short URL: **ia.cr/2018/847

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