A Plan to Write A Series of articles to Introduce Encryption Algorithms Used in PDF

I have worked on pdf-related software for almost 1 year. PDF becomes more and more popular as a document format to release, and preserve. The Security of pdf becomes an emergent issue recently.

How to pretect the pdf from unthorited users, how to restrict the permission from Pringting, copying, extracting, and how to specify the expire date or expire times?

I will write several articles to introducing the pdf security to you, in a way which is easy to understand. My aim is to make more people understand the basic knowledges of Information security and the practical implement used in pdf architecture.

I will write the articles mainly in Chinese, but 2 or 3 articles will be written in English.

Welcome to have a look !