Study Of The Secret Key Exposue In The Signature System

With the development of science and technology and the advancement of society,computers are widely used in every fields of the society and thus promotes the creation and development of the Network communication technology, which provide great convenience to people's life and works.However,everything has two sides,Science has no exception. Although Network Communication promotes and acceletes the information development and enables people to know and exchange information in time. And the security of Network communication faces serious challenge because of the technique factors and artificial attacks. The information can be deleted,tampered and replayed in the process of transmission,thus causes much unnecessary trouble to people's life and works. It is under this condition that the digital signature arises as one kind of a technology having information completeness attestation,be distinguished,resisting to deny nature and to encrypt a function.As a special digital signature, Key-Updating(Key-evolving) signatures can minimize the damage caused by secret key exposures effectively and also supply a new method to strengthen the safety control of the secret keys. The core of the signature is to divide the term of validity into several time sections,the secret key varies with the time sections change,and the public key maintains invariable throughout the time,so the security of signature is increased greatly. Thus it has a wide prospect in various aspects. But it can cause more parameters,complicated algorithms and poor running speed. So how to ensure the security of the signature under the premise of not affecting the realizing speed is an important research topic in the code academics now and future.The writer has made some beneficial trail and exploration in key-updating signatures and in the applying aspects. The following are the main research results:1. The security of a forward secure signature is analyzed and improved. It not only has the characteristic of forward secure signature,but also an easy algorithm that makes it easy to realize.2. Combining with the forward secure and proxy signature,but also a new forward secure multi-signature scheme is proposed. 3. The notion of the key-insulated signature is given. A new perfect strong key insulated signature is proposed,and is compared with the existing scheme.4. The concept of intrusion-resilient signature is introduced. A new intrusion resilient signature scheme is presented.