Part I—Cryptographic Protocols Chapter 2—Protocol Building Blocks 2.

Applied cryptography, second edition : protocols, algorithms,and source code in C

Constructions for hash functions based on a block cipher are studied where the size of the hashcode is equal to the block length of the block cipher and where the key size is approximately equal to the block length. A general model is presented, and it is shown that this model covers 9 schemes that have appeared in the literature. Within this general model 64 possible schemes exist, and it is shown that 12 of these are secure; they can be reduced to 2 classes based on linear transformations of variables. The properties of these 12 schemes with respect to weaknesses of the underlying block cipher are studied. The same approach can be extended to study keyed hash functions (MAC's) based on block ciphers and hash functions based on modular arithmetic. Finally a new attack is presented on a scheme suggested by R. Merkle.

https://lirias.kuleuven.be/bitstream/123456789/234170/2/article-48.pdf

Hash Functions Based on Block Ciphers: A Synthetic Approach

We present a divertible zero-knowledge proof (argument) for SAT under the assumption that probabilistic encryption homomorphisms exist. Our protocol uses a simple 'swapping' technique which can be applied to many zero knowledge proofs (arguments). In particular we obtain a divertible zero-knowledge proof for graph isomorphism. The consequences for abuse-free zero-knowledge proofs are also considered.

Advances in Cryptology-Eurocrypt '90

A new digital multisignature scheme using bijective public-key cryptosystems that overcomes the problems of previous signature schemes used for multisignatures is proposed. The principal features of this scheme are (1) the length of a multisignature message is nearly equivalent to that for a singlesignature message; (2) by using a one-way hash function, multisignature generation and verification are processed in an efficient manner; (3) the order of signing is not restricted; and (4) this scheme can be constructed on any bijective public-key cryptosystem as well as the RSA scheme. In addition, it is shown that the new scheme is considered as safe as the public-key cryptosystem used in this new scheme. Some variations based on the scheme are also presented.

A digital multisignature scheme using bijective public-key cryptosystems

A digital multisignature scheme using bijective public-key cryptosystem

Because of the increased cost-effectiveness of computer technology and its subsequent acceptance into the business world, computer-based message systems are likely to become the principal carriers of business correspondence. Unfortunately with the efficiency of these systems come new possibilities for crime based on interference with digital messages. But the same technology that poses the threat can be used to resist and perhaps entirely frustrate potential crimes. For some messages, a degree of privacy or secrecy is needed, which is possible with encryption. However, predicting the extent encryption will be used in electronic mail is difficult, since much depends on the cost and convenience of its applications. For nearly all messages, authenticity is a prime requirement. Authenticity implies that the message is genuine in two respects: its text has not changed since it left the sender and the identity of the sender is correctly represented in the text header or in the signature attached to the message. Neither of these authenticity indicators is sufficient by itself because an altered message from sender A is in no way different from a message appearing to come from A but in fact coming from an enemy. The technique of authentication, which is closely related to cryptography, normally uses the symmmetric type of cipher, typified by the Data Encryption Standard, or DES, algorithm. This kind of authentication is seriously deficient because both the sender and receiver must know a secret key. The sender uses the key to generate an authenticator, and the receiver uses it to check the authenticator. With this key, the receiver can also generate authenticators and can therefore forge messages appearing to come from the sender. In other words, authentication can protect both sender and receiver against thirdparty enemies, but it cannot protect one against fraud committed by the other. If A sends a message to B, for example, B might fraudulently claim to have received a different message. Supposing B takes some action in response to a genuine received message, A can still claim that B in fact forged the message. For these reasons, authentication by the customary methods using symmetric ciphers can do nothing to resolve disputes arising from the dishonesty of either sender or receiver. As a solution to the dispute problem, Diffie and Hellmant proposed the use of a digital signature based on certain public-key cryptosystems (Figure 1). The sender of the message is responsible for generating the

Davies

Papers

Applying the RSA Digital Signature to Electronic Mail