The IPP codes constructed by the method have good asymptotic behavior,which simultaneously ensure excellent anti-collusion size and length of code words under mass of users.

This paper focus on protection against illegal production of copyrighted digital images and provides a fingerprinting scheme that employs the thought of joint fingerprinting and decryption(JFD) and the idea of concatenated codes,which has a good performance on user capacity and anti-collusion property.

Comparing with other scholar\'s off-line TTP multi-party non-repudiation protocols, our protocol meets consistent evidence properties, which means that whenever protocol finished through TTP, the evidence participants got is consistent, in the meanwhile, our protocol can provide non-repudiation, strong fairness, confidentiality and collusion attack freeness.

The Reasons for the Collusions among Bidders in the Power Market;

Analysis of a mechanism design of collusion;

Research on compensation contract for collusion-proof in symmetric information;

And the issue of how to ensure project quality and avoid conspiracy between the supervising company and unit in charge of construction is also analyzed.

The key to prevent the conspiracy of managers and officials is to hit hard such malpractice.

We find that the pursue to benefits of short-term is incentive of auditconspiracy, and that it has close relation to the market situation.

On the basis of transforming Mu s scheme into public-key traitor tracing scheme,the advantages such as providing multiple-service,collusion-resistance and black-box tracing are added.