pdf文件中的AES 256位加密

Question

I am working on PDF Security and trying to encrypt User and Owner password using AES 256-bit encryption algo.

I have generated these keys successfully (using crypto library) but when these keys are written in PDF Encryption dictionary they do not seem to work. ( Acrobat does not open the file)

I have explored iTextSharp which does the encryption of pdf file. Now I want to decrypt that file so that some how I get the idea how iTextSharp has done it. But unfortunately I did not find any tool to do so. The file encrypted using iTextSharp is correctly opened in Adobe Acrobat .

Answer 1

while encrypting keys you have to use SASLprep (IETF RFC 4013) profile of stringprep (IETF RFC 3454). The thing i want to add is lib ICU can generate SASLprep (IETF RFC 4013) profile easily.