This thesis presents fast and practical methods for generating randomly distributed pairs of the form (x, gX mod p) or (x, xe mod N), using precomputation. These generation schemes are of wide applicability for speeding-up public key systems that depend on exponentiation and offer a smooth memory-speed trade-off. The steps involving exponentiation in these systems can be reduced significantly i...

Due to importance of security in many critical applications in Mobile Adhoc Networks (MANETs) and the limitation of the resources in mobile devices, it is important to have secure lightweight cryptosystem. The easier key management and less overhead of transmitting processes make Public Key Cryptosystems (PKC) suitable for MANETs. Obviously, the main issue regarding to the use of PKC is to ensu...

VHDL model descriptions can be processed by synthesis tools in order to derive a netlist of basic logic elements, which can then be fed into place and route tools. Based on this design flow Register Transfer Level (RTL) descriptions have proven to be well suited to efficiently design integrated circuits. In addition to using commercial synthesis tools, there is a lot of potential for applicatio...

Potential weaknesses in public key cryptosystem design and use are identiied with emphasis on a particular vulnerability resulting from the encryption of ordinary natural language plaintext. This weakness occurs when an insuuciently long block length is used to encrypt low entropy natural language and ordinary numeric plaintext rendered in 8-bit character sets such as ASCII or EBCDIC. A compute...

Gradually, copyright-protection protocols have attracted much attention in that they provide effective copyright protection mechanisms. Asymmetric copyright-protection protocols allow the buyer to know and possess the protected content yet the seller has no idea about it. Subsequently, if an illegal copy is found, the seller can identify the buyer by cooperating with a trusted third party. Most...

A distributed key generation (DKG) protocol is a central segment in distributed cryptosystems. It permits a gathering of members to mutually produce a pair of keys (private key and public key) without assuming any trusted member. The public key is output in clear but only authorised subgroups of members are able to reconstruct or utilize the private key. Existing study on DKG protocols assumes ...

Establishment of pairwise keys between sensor nodes in a sensor network is a difficult problem due to resource limitations of sensor nodes as well as vulnerability to physical captures of sensor nodes by the enemy. Public-key cryptosystems are not much suited for most resource-constrained sensor networks. Recently, elliptic curve cryptographic techniques show that public key cryptosystem is als...

The discrete logarithm problem is one of the backbones in public key cryptography. In this paper we study the discrete logarithm problem in the group of circulant matrices over a finite field. This gives rise to secure and fast public key cryptosystems.

“Certificateless public-key cryptosystem” is a new and attractive paradigm, which avoids the inherent key escrow property in identity-based public-key cryptosystems, and does not need expensive certificates as in the public key infrastructure. A strong security model for certificateless public key encryption was established by Al-Riyami and Paterson in 2003. In this paper, we first present a se...