PROJECT TITLE :

Attribute-Based Encryption With Efficient Verifiable Outsourced Decryption

ABSTRACT:

Attribute-based encryption (ABE) with outsourced decryption not only enables fine-grained sharing of encrypted knowledge, but also overcomes the efficiency disadvantage (in terms of ciphertext size and decryption cost) of the quality ABE schemes. In specific, an ABE theme with outsourced decryption permits a 3rd party (e.g., a cloud server) to transform an ABE ciphertext into a (short) El Gamal-sort ciphertext using a public transformation key provided by a user thus that the latter can be decrypted much a lot of efficiently than the previous by the user. However, a shortcoming of the first outsourced ABE theme is that the correctness of the cloud server’s transformation can not be verified by the user. That's, an finish user could be cheated into accepting a wrong or maliciously reworked output. During this paper, we have a tendency to 1st formalize a security model of ABE with verifiable outsourced decryption by introducing a verification key within the output of the encryption algorithm. Then, we have a tendency to present an approach to convert any ABE theme with outsourced decryption into an ABE theme with verifiable outsourced decryption. The new approach is straightforward, general, and nearly optimal. Compared with the original outsourced ABE, our verifiable outsourced ABE neither will increase the user’s and therefore the cloud server’s computation prices except some nondominant operations (e.g., hash computations), nor expands the ciphertext size except adding a hash worth (which is <20 byte for eighty-bit security level). We have a tendency to show a concrete construction primarily based on Green et al.’s ciphertext-policy ABE theme with outsourced decryption, and provide a close performance analysis to demonstrate the benefits of our approach.