Short CCA-Secure Attribute-Based Encryption

Chosen-ciphertext attacks are typical threat on public-key encryption schemes. We propose a technique of individually converting an attribute-based encryption scheme (ABE) which is secure against chosen-plaintext attacks into an ABE scheme which is secure against chosen-ciphertext attacks. Our technique is helpful when a Diffie-Hellman tuple to be verified is in the target group of a bilinear map. The employed technique, the Twin Diffie-Hellman Trapdoor Test of Cash, Kiltz and Shoup, results in expansion of the secret-key length and the decryption cost by a factor of four, while the public-key and the ciphertext lengths and the encryption cost remain almost the same