Mohsen Toorani

Sequences and Linear Codes from Highly Nonlinear Functions

Cryptanalysis of an Elliptic Curve-based Signcryption Scheme

The signcryption is a relatively new cryptographic technique that is supposed to fulfill the functionalities of encryption and digital signature in a single logical step. Although several signcryption schemes are proposed over the years, some of them are proved to have security problems. In this paper, the security of Han et al.’s signcryption scheme is analyzed, and it is proved that it has ma...

A secure cryptosystem based on affine transformation

In this paper, it is proved that Lin et al.'s scheme that tried to strengthen the Hill cipher against the known-plaintext attack has several security flaws and is vulnerable to the chosenciphertext attack. This paper also introduces a secure and efficient symmetric cryptosystem based on affine transformation. The proposed cryptosystem includes an encryption algorithm that is an improved variant...

An Elliptic Curve-based Signcryption Scheme with Forward Secrecy

An elliptic curve-based signcryption scheme is introduced in this paper that effectively combines the functionalities of digital signature and encryption, and decreases the computational costs and communication overheads in comparison with the traditional signaturethen-encryption schemes. It simultaneously provides the attributes of message confidentiality, authentication, integrity, unforgeabi...

Cryptanalysis of Two PAKE Protocols for Body Area Networks and Smart Environments

Password-authenticated key exchange (PAKE) protocols enable two or more entities to authenticate each other and share a strong cryptographic key based on a pre-shared human memorable password. In this paper, we present several attacks on two recent elliptic curve-based PAKE protocols that have been suggested for use in body area networks and smart environments. A variant of the first PAKE proto...