POSTER: Ciphertext-Policy Attribute-Based Encryption Method with Secure Decryption Key Generation and Outsourcing Decryption of ABE Ciphertexts

Abstract

Attribute-based encryption (ABE) allows user to encrypt and decrypt data based on user attributes, and can be applied in some promising area such as mobile cloud storage. Since these are massive users in these applications, secure online transmission of decryption key is necessary. In this paper, a ciphertext-policy attribute-based encryption (CP-ABE) method with secure decryption key generation and outsourcing decryption of ABE ciphertexts is proposed. In the method, a user’s public key information is embedded into his decryption key in the key generation algorithm. Both the user’s decryption key and private key are needed to decrypt a ciphertext. With only the decryption key, a ciphertext cannot be decrypted, so the decryption key is secure and can be directly transmitted online. This saves some costs comparing to other transmission approaches, such as Secure Sockets Layer (SSL). Furthermore, the method supports outsourcing the decryption of ABE ciphertexts. Our analysis and experiment results prove that our method is more efficient than the existing outsourcing methods which generally use key transformation technique.