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I need a program that scans for unencrypted files.

The files are encrypted with PGP, GPG, and WinZipAES256, so the program needs to be able to recognize these formats as encrypted.

Since I need to scan the actual file content rather than checking the file extension only, I researched ways to detect file entropy.

I can use a program like http://www.fourmilab.ch/random/ with good results; however, it might be a problem if a picture of sensitive data is uploaded, since the program returns a high value for pictures.

Does anyone know a better way to accomplish this task? Any help would be appreciated.

share|improve this question
    
uploaded? I clearly don't understand what it is you are trying to do. on the topic of file data however, it may not be possible to tell whether a given file is encrypted, unless you constrain the universe of possible file formats. it would be impossible to tell whether a file contained encoded data using a scheme you are not familiar with or encrypted data. –  Frank Thomas Jul 7 '13 at 6:16
    
I think the OP has already constrained the allowed types to PGP, GPG, and WinZip AES256 containers. The issue then becomes testing if the file is one of these. –  Dan D. Jul 7 '13 at 6:34
    
Yes, uploaded. Clients are uploading files to these shares via FTP. Most of the files are encrypted in those formats. However, I simply want to scan for unencrypted data in general. I stated those to be sure they were taken into account in people's answers. It seems the best way to complete this task is to return file names in a report if their entropy is less than say, 7.9 (since 8 is random and the best encryption methods yield entropy of at least 7.9). What do you guys think? –  user1040362 Jul 7 '13 at 23:55

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