Plaintext-Checkable Encryption

We study the problem of searching on encrypted data, where the search is performed using a plaintext message or a keyword, rather than a message-specific trapdoor as done by state-of-the-art schemes. The use cases include delegation of key-word search e.g. to a cloud data storage provider or to an email server, using a plaintext message. We define a new cryptographic primitive called plaintext-checkable encryption (PCE), which extends public-key encryption by the following functionality: given a plaintext, a ciphertext and a public key, it is universally possible to check whether the ciphertext encrypts the plaintext under the key. We provide efficient generic random-oracle constructions for PCE based on any probabilistic or deterministic encryption scheme; we also give a practical construction in the standard model. As another application we show how PCE can be used to improve the efficiency in group signatures with verifier-local revocation (VLR) and backward unlinkability. These ...

• Type: Journal
• Year: 2012
• Where: CTRSA
• Authors: Sébastien Canard, Georg Fuchsbauer, Aline Gouget, Fabien Laguillaumie
• Keywords: Cryptology, CTRSA 2012, Group Signatures, Key Word Search, Random Oracle