Log system based on watermark technology it can add watermark in log record , and protect log record ' s originality and unchangeableness . it provides a powerful and undeniable proof for log audit ; 5 4 、数字水印日志在日志中加入数字水印保证日志的原始性和不可更改性，为日志审计提供了强有力的不可抵赖的依据。
2.
As there are three main defects in the applications of bar codes commonly used in packaging , which are the lack of generative algorithm of 2d pdf417 bar code , the irreversibility of the built bar code , and the unchangeableness of the color of bar code , this paper aims to design a new class of bar code based on coding principles of various bar codes and make it as an integrated software by using the methods of software programming ; and it also aims to remedy the three defects as mentioned above 本课题从目前包装常用条码软件在应用过程中存在的缺少二维pdf417码生成算法、生成条码不可修改、条码颜色太过单一这三个主要缺陷出发，在了解了各种条码码制的编码原理后，通过设计一个全新的条码类结合软件编程知识最终实现软件化，并针对以上缺陷和不足给予了功能上的改进。
