A new technique for compacting secret key in attribute-based broadcast encryption

Public-key encryption has been generalized to adapt to more and more practical applications. Broadcast encryption, introduced by Fiat and Naor in 1993, aims for applications in pay-TV or satellite transmission and allows a sender to securely send private messages to any subset of users, the target set. Sahai and Waters introduced Attributebased Encryption (ABE) to define the target set in a more structural way via access policies on attributes. Attribute-based Broadcast Encryption (ABBE) combines the functionalities of both in an efficient way. In the relevant applications such as pay-TV, the users are given a relatively small device with very limited secure memory in a smartcard. Therefore, it is of high interest to construct schemes with compact secret key of users. Even though extensively studied in the recent years, it is still an open question of constructing an efficient ABBE with constant-size private keys for general forms of access policy such as CNF or DNF forms. This question was partially solved at ESORICS '15 where Phuong et al. introduced a constant secret-key size ABBE. But they manage restrictive access policies only supporting AND-gates and wildcards. In this paper, we solve this open question and propose an efficient constantsize private key ciphertext-policy attribute-based broadcast encryption scheme for DNF form. In particular, we also present the optimization in implementing our proposed scheme. Springer International Publishing AG 2016.Scopu

Edit distance based encryption and its application

Edit distance, also known as Levenshtein distance, is a very useful tool to measure the similarity between two strings. It has been widely used in many applications such as natural language processing and bioinformatics. In this paper, we introduce a new type of fuzzy public key encryption called Edit Distance-based Encryption (EDE). In EDE, the encryptor can specify an alphabet string and a threshold when encrypting a message, and a decryptor can obtain a decryption key generated from another alphabet string, and the decryption will be successful if and only if the edit distance between the two strings is within the pre-defined threshold. We provide a formal definition and security model for EDE, and propose an EDE scheme that can securely evaluate the edit distance between two strings embedded in the ciphertext and the secret key. We also show an interesting application of our EDE scheme named Fuzzy Broadcast Encryption which is very useful in a broadcasting network