Proxy re-encryption (PRE) enables a semi-trusted proxy to delegate the decryption right by re-encrypting the ciphertext under the delegator’s public key to an encryption under the public key of delegatee. Fueled by the translation ability, PRE is regarded as a promising candidate to secure data sharing in a cloud environment. However, the security of the PRE will be totally destroyed in case th...

In this paper, we describe efficient forgery and full-key recovery attacks on the `-IC− signature scheme recently proposed at PKC 2007. This cryptosystem is a multivariate scheme based on a new internal quadratic primitive which avoids some drawbacks of previous multivariate schemes: the scheme is extremely fast since it requires one exponentiation in a finite field of medium size and the publi...

In a threshold broadcast encryption scheme, a sender chooses (ad-hoc) a set of n receivers and a threshold t, and then encrypts a message by using the public keys of all the receivers, in such a way that the original plaintext can be recovered only if at least t receivers cooperate. This kind of scheme has many applications in mobile ad-hoc networks, characterized by their lack of infrastructur...

Article history: Received 29 November 2007 Received in revised form 6 May 2014 Accepted 22 August 2014 Available online 26 September 2014

An identity-based signcryption scheme with (t, n) shared unsigncryption is proposed, which is the integration of the signcryption scheme, the (t, n) threshold scheme and zero knowledge proof for the equality of two discrete logarithms based on the bilinear map. In this scheme, any third party can verify the validity of the signature, but only more than t members in the recipient group can coope...

A Wireless Sensor Network has sensor nodes which have limited computational power and memory size. Due to the nature of the network, the data is vulnerable to attacks. Thus, maintaining confidentiality is an important issue. To compensate for this problem, there are many countermeasures which utilize common or public key cryptosystems that have been proposed. However, these methods have problem...

In this paper, we describe efficient forgery and full-key recovery attacks on the `-IC− signature scheme recently proposed at PKC 2007. This cryptosystem is a multivariate scheme based on a new internal quadratic primitive which avoids some drawbacks of previous multivariate schemes: the scheme is extremely fast since it requires one exponentiation in a finite field of medium size and the publi...

This paper studies the security of a secure communication scheme based on two discrete-time intermittently chaotic systems synchronized via a common random driving signal. Some security defects of the scheme are revealed: 1) The key space can be remarkably reduced; 2) the decryption is insensitive to the mismatch of the secret key; 3) the key-generation process is insecure against known/chosen-...

A new multivariate public-key cryptosystem (MPKC) with the security based on the difficulty of the prime factoring is proposed. Unlike conventional cryptosystems such as RSA, most MPKCs are expected secure against quantum computers, and their operation of encryption and decryption is expected quick, because they do not need exponential operation. However, their security against quantum computer...

Audio communications and computer networking play essential roles in our daily lives, including many domains with different scopes. Developments these technologies are quick. In consequence, there is a dire need to secure up date. This paper presents an efficient model for audio signal transmission over the wireless noisy uncorrelated Rayleigh fading channel. Also, performance of utilized multi...