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ACF Library

DecryptFile

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Description: Decrypts a file on disk

FileMaker Prototype: 

Set Variable [$res; ACF_Run("DecryptFile"; string_path;  string_key)]

Category: ENCRYPTION

Function source:

/*

   Decrypt a file on disk. Function asks for file, 
   and create a new file removing .encrypted as extention. 
   the function verifies that the filename has .encrypted in it. 
   
*/

function DecryptFile (string path, string key)
   string opath; 
   int x; 
   string content, decrypted; 
   if ( path == "") then   
      path = select_file ( "Select a encrypted file to decrypt"); 
   end if
   if ( path != "") then
      if ( pos ( path, ".encrypted")>0) then
         if ( key == "") then
            key = "SablaBabla029c";  
         end if 
         x = open ( path, "r"); 
         content = read ( x ); 
         close (x); 
         decrypted = decrypt ( aes256cbc, key, content, binary); 
         opath = substitute (path,  ".encrypted", ""); 
         x = open ( opath, "w"); 
         write ( x, decrypted ) ; 
         close (x); 
         // delete_file (path); 
      end if
   end if
   return "OK"; 
end

DecryptFile do a AES256 decryption on a file on disk, it produces a new file without the excrypted extention, with the original name.

If no filename is given, the user is asked to select a file. If no key is given, a default key is used (that should be changed when you copy this function). See the line `key = "...".

The function tests for .encrypted extention of the input path.

Example 

Set Variable [$res; ACF_Run("DecryptFile"; "~/Desktop/MyPlainFile.docx.encrypted";  "MySecretKey")]

The file MyPlainFile.docx appears on the users desktop.

We have commented out the final "delete file", but this can be included after some testing.

Se also EncryptFile

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