We began the course with a discussion and review of private key cryptography and then started moving into the realm of public key cryptography. During this lecture, we will discuss four public key schemes. Even though RSA preceded the other schemes presented here, we will review ElGamal and introduce DSS rst (both mod p schemes), in hopes of providing more background and motivation for some of ...

Providing security service in wireless sensor networks using authentication techniques turns out to be a non-trivial task due to network resource constraints. To improve the network security it is often necessary to combine intrusion detection techniques with the key management protocols. Several symmetric key cryptographic solutions proposed earlier are inefficient against node compromise atta...

We present a simple, natural random-oracle (RO) model scheme, for a practical goal, thatis uninstantiable, meaning is proven in the RO model to meet its goal yet admits no standard-model instantiation that meets this goal. The goal in question is IND-CCA-preserving asym-metric encryption which formally captures security of the most common practical usage ofasymmetric encryption,...

A generalized group-oriented cryptosystem (GGOC) based on ElGamal cryptosystem was proposed by Yang et al. in 2003. This study shows that if the authorized decryption sets of users are not properly predetermined in Yang et al.’s GGOC, an unauthorized decryption set of users can recover the encrypted message without difficulty. This study also presents an improved protocol to resist such an attack.