A digraph of order at least k is k-traceable if each of its subdigraphs of order k is traceable. We note that 2-traceable oriented graphs are tournaments and for k ≥ 3, k-traceable oriented graphs can be regarded as generalized tournaments. We show that for 2 ≤ k ≤ 6 every k-traceable oriented graph is traceable, thus extending the well known fact that every tournament is traceable. This result...

Most of the existing ring signature schemes are based on traditional cryptography, such as RSA and discrete logarithm. Unfortunately these schemes would be broken if quantum computers emerge. The MQ-problem based PublicKey Cryptosystem (MPKC) is an important alternative to traditional PKCs for its potential to resist future attacks of quantum computers. In this paper, we proposed a new ring sig...

In this paper, we propose a dual version of the first threshold ring signature scheme based on error-correcting code proposed by Aguilar et. al in [1]. Our scheme uses an improvement of Véron zero-knowledge identification scheme, which provide smaller public and private key sizes and better computation complexity than the Stern one. This scheme is secure in the random oracle model. Keywords—Ste...

Ring signatures, introduced by Rivest, Shamir and Tauman (ASIACRYPT 2001), allow to sign a message on behalf of a set of users (called a ring) while guaranteeing authenticity, i.e. only members of the ring can produce valid signatures, and anonymity, i.e. signatures hide the actual signer. In terms of efficiency, the shortest ring signatures are of size Θ(logn), where n is the size of the ring,...

We present theoretical predictions for photometric and spectroscopic signatures of rings around transiting extrasolar planets. On the basis of a general formulation for the transiting signature in the stellar light curve and the velocity anomaly due to the Rossiter effect, we compute the expected signals analytically for a face-on ring system, and numerically for more general configurations. We...

Identity-based (ID) cryptosystems avoid the necessity of cer-tiicates to authenticate public keys in a digital communications system. This is desirable, specially for these applications which involve a large number of public keys in each execution. For example, any computation and veriication of a ring signature, where a user anonymously signs a message on behalf of a set of users including him...

In this paper we present a new k out of n visual cryptography scheme which does not only meet the requirements of the basic visual cryptography scheme deened by Naor and Shamir 5] but is also traceable. With a k out of n scheme it is not possible to reveal the original secret by stacking less than k transparencies. In general one can assume that it is very unlikely that there are k shareholders...

In this article, we propose a new lattice-based threshold ring signature scheme, modifying Aguilar’s code-based solution to use the short integer solution (SIS) problem as security assumption, instead of the syndrome decoding (SD) problem. By applying the CLRS identification scheme, we are also able to have a performance gain as result of the reduction in the soundness error to 1/2 per round. S...