From the Publisher:
A valuable reference for the novice as well as for the expert who needs a wider scope of coverage within the area of cryptography, this book provides easy and rapid access of information and includes more than 200 algorithms and protocols; more than 200 tables and figures; more than 1,000 numbered definitions, facts, examples, notes, and remarks; and over 1,250 significant references, including brief comments on each paper.

Handbook of Applied Cryptography

In several distributed systems a user should only be able to access data if a user posses a certain set of credentials or attributes. Currently, the only method for enforcing such policies is to employ a trusted server to store the data and mediate access control. However, if any server storing the data is compromised, then the confidentiality of the data will be compromised. In this paper we present a system for realizing complex access control on encrypted data that we call ciphertext-policy attribute-based encryption. By using our techniques encrypted data can be kept confidential even if the storage server is untrusted; moreover, our methods are secure against collusion attacks. Previous attribute-based encryption systems used attributes to describe the encrypted data and built policies into user's keys; while in our system attributes are used to describe a user's credentials, and a party encrypting data determines a policy for who can decrypt. Thus, our methods are conceptually closer to traditional access control methods such as role-based access control (RBAC). In addition, we provide an implementation of our system and give performance measurements.

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Ciphertext-Policy Attribute-Based Encryption

As more sensitive data is shared and stored by third-party sites on the Internet, there will be a need to encrypt data stored at these sites. One drawback of encrypting data, is that it can be selectively shared only at a coarse-grained level (i.e., giving another party your private key). We develop a new cryptosystem for fine-grained sharing of encrypted data that we call Key-Policy Attribute-Based Encryption (KP-ABE). In our cryptosystem, ciphertexts are labeled with sets of attributes and private keys are associated with access structures that control which ciphertexts a user is able to decrypt. We demonstrate the applicability of our construction to sharing of audit-log information and broadcast encryption. Our construction supports delegation of private keys which subsumesHierarchical Identity-Based Encryption (HIBE).

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Attribute-based encryption for fine-grained access control of encrypted data

Suppose we are given a proof of knowledge P in which a prover demonstrates that he knows a solution to a given problem instance. Suppose also that we have a secret sharing scheme S on n participants. Then under certain assumptions on P and S, we show how to transform P into a witness indistinguishable protocol, in which the prover demonstrates knowledge of the solution to some subset of n problem instances out of a collection of subsets denned by S. For example, using a threshold scheme, the prover can show that he knows at least d out of n solutions without revealing which d instances are involved. If the instances axe independently generated, we get a witness hiding protocol, even if P did not have this property. Our results can be used to efficiently implement general forms of group oriented identification and signatures. Our transformation produces a protocol with the same number of rounds as P and communication complexity n times that of P. Our results use no unproven complexity assumptions.

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Proofs of Partial Knowledge and Simplified Design of Witness Hiding Protocols

We construct an Attribute-Based Encryption (ABE) scheme that allows a user's private key to be expressed in terms of any access formula over attributes. Previous ABE schemes were limited to expressing only monotonic access structures. We provide a proof of security for our scheme based on the Decisional Bilinear Diffie-Hellman (BDH) assumption. Furthermore, the performance of our new scheme compares favorably with existing, less-expressive schemes.

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Attribute-based encryption with non-monotonic access structures

Cycles within specified distance from each vertex

In 1996, Ota and Tokuda showed that a star-free graph with sufficiently high minimum degree admits a 2-factor. More recently it was shown that the minimum degree condition can be significantly reduced if one also requires that the graph is not only star-free but also of sufficiently high edge-connectivity. In this paper we reduce the minimum degree condition further for star-free graphs that also avoid WM r, where WM r is the graph K1 + rK2.

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Two forbidden subgraphs and the existence of a 2-factor in graphs

LetK be a connected graph. A spanning subgraphF ofG is called aK-factor if every component ofF is isomorphic toK. On the existence ofK-factors we show the following theorem: LetG andK be connected graphs andp be an integer. Suppose|G| = n|K| and 1 <p < n. Also suppose every induced connected subgraph of orderp|K| has aK-factor. ThenG has aK-factor.

On component factors

Studies on the Pathogenetic Microbes in Bone Marrow in Typhoid and Paratyphoid

(Received for publication, August 22, 1951) In 1948, an epidemic of Japanese Encephalitis occurred throughout the country. Sendai with its environs was not excluded. Descriptions of the disease have appeared in a considerable number, especially since 1935. We desire to report our own cases of the disease which prevailed in the summer of 1948 in this region. Our own cases are 31 in all. These cases were treated either in the Children's Department of the Tohoku University Hospital or in the Sendai Isolation Hospital. I. Sex, Age and month of the year Sex. Of the 31 child patients 23 cases (74.2%) were males and 8 (25.8 %) females. Such a predominance of the male sex was already noted in many reports in 1935, and it has been noted too in this year's epidemic by other authors. Of our own cases one male and two female cases were fatal. It is to be noted here that there was not a single case of the disease beside the patient in each family of our own cases. Age. Of our own 31 cases, the youngest case was a boy of 8 months old. The incidence of age will be seen from Table I (Cf. Table I) which shows 11 cases-the maximum number-between 6 and 9 years of age.

Akira Saito

Papers

Cycles within specified distance from each vertex

Two forbidden subgraphs and the existence of a 2-factor in graphs

On component factors

Studies on the Pathogenetic Microbes in Bone Marrow in Typhoid and Paratyphoid

Clinical picture of Japanese encephalitis in children in 1948.