The interaction interface between human thrombin and human factor V (FV), necessary for complex formation and cleavage to generate factor Va, was investigated using a site-directed mutagenesis strategy. Fifty-three recombinant thrombins, with a total of 78 solvent-exposed basic and polar residues substituted with alanine, were used in a two-stage clotting assay with human FV. Seventeen mutants ...

Ciphertext-policy attribute-based encryption (CP-ABE) is an access control mechanism where a data provider encrypts a secret message and then sends the ciphertext to the receivers according to the access policy which she/he decides. If the attributes of the receivers match the access policy, then they can decrypt the ciphertext. This manuscript shows a relation between ABE and identity-based en...

Bilinear groups are often used to create Attribute-Based Encryption (ABE) algorithms. In particular, they have been used to create an ABE system with multi authorities, but limited to the ciphertext-policy instance. Here, for the first time, we propose two multi-authority key-policy ABE systems. In our first proposal, the authorities may be set up in any moment and without any coordination. A p...

Attribute-Based Encryption (ABE) is regarded as one of the most desirable cryptosystems realizing data security in the cloud storage systems. Functional Encryption (FE) which includes ABE and the ABE system with multiple authorities are studied actively today. However, ABE has the attribute revocation problem. In this paper, we propose a new revocation scheme using update information, i.e., rev...

For practical data sharing applications, many attributebased encryption (ABE) schemes were proposed with different kinds of properties, such as supporting large universe, revocation, verification and so on. However, existing schemes seldom support these three important properties simultaneously. In this paper, we present a directly revocable and verifiable key-policy ABE scheme for large univer...

We propose adaptively secure attribute-based encryption (ABE) schemes for boolean formulas over large universe attributes from the decisional linear (DLIN) assumption, which allow an arbitrary number of attribute reuse in an available formula without the previously employed redundant multiple encoding technique. Based on the key-policy (KP)ABE scheme, we have an adaptively secure communication-...

In this work, we present HIBE and ABE schemes which are “unbounded” in the sensethat the public parameters do not impose additional limitations on the functionality of thesystems. In all previous constructions of HIBE in the standard model, a maximum hierarchydepth had to be fixed at setup. In all previous constructions of ABE in the standard model,either a small universe size o...

Inside a dispersed foriegn atmosphere, anyone receives a untrusted company which has a change for better crucial allowing this foriegn to turn any kind of ABE ciphertext fulfilled through the wearer's features. Stability of ABE technique with outsourced decryption makes certain that a foe (including any destructive cloud) aren't going to be capable to study everything about the encrypted meanin...

Recently, cryptographic access control has received a lot of attention, mainly due to the availability of efficient Attribute-Based Encryption (ABE) schemes. ABE allows to get rid of a trusted reference monitor by enforcing access rules in a cryptographic way. However, ABE has a privacy problem: The access policies are sent in clear along with the ciphertexts. Further generalizing the idea of p...

We propose new fully secure attribute based encryption (ABE) systems for polynomialsize circuits in both key-policy and ciphertext-policy flavors. All the previous ABE systems for circuits were proved only selectively secure. Our schemes are based on asymmetric graded encoding systems in composite-order settings. The assumptions consist of the Subgroup Decision assumptions and two assumptions w...