A New Knapsack Public-Key Cryptosystem Based on Permutation Combination Algorithm
A new secure knapsack cryptosystem based on the
Merkle-Hellman public key cryptosystem will be proposed in this
paper. Although it is common sense that when the density is low, the
knapsack cryptosystem turns vulnerable to the low-density attack. The
density d of a secure knapsack cryptosystem must be larger than
0.9408 to avoid low-density attack. In this paper, we investigate a
new Permutation Combination Algorithm. By exploiting this
algorithm, we shall propose a novel knapsack public-key cryptosystem.
Our proposed scheme can enjoy a high density to avoid the
low-density attack. The density d can also exceed 0.9408 to avoid
the low-density attack.
Public key, Knapsack problem, Knapsack cryptosystem, low-density attack.
A Fair Non-transfer Exchange Protocol
Network exchange is now widely used. However, it still
cannot avoid the problems evolving from network exchange. For
example. A buyer may not receive the order even if he/she makes the
payment. For another example, the seller possibly get nothing even
when the merchandise is sent. Some studies about the fair exchange
have proposed protocols for the design of efficiency and exploited the
signature property to specify that two parties agree on the exchange.
The information about purchased item and price are disclosed in
this way. This paper proposes a new fair network payment protocol
with off-line trusted third party. The proposed protocol can protect
the buyers- purchase message from being traced. In addition, the
proposed protocol can meet the proposed requirements. The most
significant feature is Non-transfer property we achieved.
E-commerce, digital signature, fair exchange, security.