Attribute-based Signcryption with Ciphertext-policy and Claim-predicate Mechanism

Secure sharing of Personal Health Records in cloud computing: Ciphertext-Policy Attribute-Based Signcryption

“…But, both of the key size are less than others if the number is small. On the other hand, it is obvious that the ciphertext size and signcryption cost of our scheme are less than those in [24,25,26].…”

“…Most of the previous works [21,22,23,24] adopt the threshold policy as their access control structure which is only a coarse-grained level and supports only simple predicates. While the schemes in [25,26] support monotone tree policy which is similar with ours, the construction of this kind of policy is a little more complex. Since we consider the fact that some attributes may appear more than once in the access structure which is not taken into account by previous works [21,22,23,24,25,26], the size of signing secret key and decryption secret key grow linearly with the number of times of key attributes (must be used in signing or decryption).…”

“…While the schemes in [25,26] support monotone tree policy which is similar with ours, the construction of this kind of policy is a little more complex. Since we consider the fact that some attributes may appear more than once in the access structure which is not taken into account by previous works [21,22,23,24,25,26], the size of signing secret key and decryption secret key grow linearly with the number of times of key attributes (must be used in signing or decryption). But, both of the key size are less than others if the number is small.…”

“…The overhead is less than the combination of two steps (Signature + Encryption). Gagné et al proposed the first threshold policy attribute-based signcryption in [21] which is followed by a number of other schemes [22,23,24,25,26]. In [21] the signing attributes are separated from encryption/decryption attributes so that the signing and decryption rights can be separated.…”

“…In this section, we compare the performance of several existing ABSC schemes [21,22,23,24,25,26] with ours in terms of secret key size, ciphertext size, computation costs of signcryption and designcryption, and access structure in Table 2. A list of notations that we use to evaluate the efficiency of different schemes are shown in Table 3.…”