As a newbie, I am going to ask a stupid question again. In my current project, I have to make website mixed with google docs, dropbox and mediafire. In addition, when a user will submit a file, that file will be checked whatever the file is digitally signed or not (http://en.wikipedia.org/wiki/Digital_signature).
Now, I need to show that, one file format (either doc or pdf) will be examined to determine that, is it digitally signed or not ? I read the doc file but there is no difference between a signed file and a unsigned file in reading. I thought I would try it in OPENSSL(php), but I did not find any document which indicates doc file can be read for digital signature.
Now, my alternative is java, C#, asp.net. But, I do not know whatever it is possible in any of this one?
In a word, my question is, How to get information of digital signature from a doc/pdf file and how can i verify its signed or not?
ANY OPINION will be a plus point for me (as a newbie, i am in big trouble).
THANK YOU VERY MUCH FOR READING THIS and sorry for my bad English.