Quantum string seal is insecure

Quantum String Seal Is Insecure

A quantum string seal encodes the value of a (bit) string as a quantum state in such a way that everyone can extract a non-negligible amount of available information on the string by a suitable measurement. Moreover, such measurement must disturb the quantum state and is likely to be detected by an authorized verifier. In this way, the intactness of the encoded quantum state plays the role of a...

Secure quantum signatures using insecure quantum channels

Kish’s key exchange scheme is insecure

Kish proposed a scheme to exchange keys between two parties under the concealment of thermal noise. We show that the theoretical model in the scheme implicitly assumes thermal equilibrium throughout the communication channel. This assumption, however, is invalid in real communication systems. A slight temperature difference in the channel, as demonstrated in the paper, will lead to security fai...

The Password Change Phase is Still Insecure

In 2004, W. C. Ku and S. M. Chen proposed an efficient remote user authentication scheme using smart cards to solve the security problems of Chien et al.’s scheme. Recently, Hsu and Yoon et al. pointed out the security weaknesses of the Ku and Chen’s scheme Furthermore, Yoon et al. also proposed a new efficient remote user authentication scheme using smart cards. Yoon et al. also modified the p...

Cosmological Quantum String Vacua and String-String Duality

Implications of string-string dualities to cosmological string vacua are discussed. Cosmological vacua of classical string theories comprise of disjoint classses mapped one another by scale-factor T-duality. Each classes are, however, afflicted with initial/final cosmological singularities. It is argued that quantum string theories and string-string dualities dramatically resolve these cosmolog...