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On Sun, 13 Dec 2015 16:16:15 +0000 Martijn Grooten <martijn@xxxxxxxxxxxxxxxxxx> wrote: > On Sun, Dec 13, 2015 at 03:42:51PM +0000, Neil Winchurst wrote: > > It seemed so simple to me. Change an already existing file by > > adding a password. From now on when I click on that file to open it > > a small window appears asking for the password. I type in the > > password and the file opens and I can treat like any normal file. > > Without the password I cannot access it. > > When you click on a file to open it, your computer looks at its > extension (.odf, .mp3, .txt etc.) to decide which program to use to > open it. If the name of the encrypted file wasn't different, the > program (for example LibreOffice it it's an .odf file) wouldn't know > how to handle the encrypted content. > > Of course, the encryption tool could give the file a new name, e.g. > mydocument.odf.encrypted and then the decryption tool would show a > window to enter your password upon clicking it. It could then open the > file with the correct program (LibreOffice in this case). > > But this program doesn't know about the file being encrypted, so it > might save temporary unencrypted copies on the system. These could be > tidied up when closing the file, when the encryption program takes > control, but what if you turn off the computer in the meantime? > > For some users, such scenarios might not matter, but for many others > they do; hence no one would want to write an encryption tool like the > one you describe (or so I would imagine), even though the request is > entirely reasonable. > > However, apart from using an encrypted directory or partition, it's > worth noting that several programs (including LibreOffice) allow you > to encrypt files. In this case, the program itself knows the file is > encrypted. > > Martijn. > > Thanks for all that help.I am asking the wrong question it seems. I am not wanting the file to be encrypted at all. What I am looking for is a way to add a password to any file (leaving the file itself unchanged) so that I need to enter that password in order to access that file. As I said, when I click on the file a small window comes up asking for the password. Type that in and I can access the file. If I cannot provide the password the file won't open. I envisage the password check to happen first, then and only then, if I have provided the correct password, will the program look at the extension to decide which program to use to run it. I was also hoping to add a password as above to any folder. My accounts folder would be a good example. Rather than set up a password for each file, just one for the folder. Yes, I do know that individual files in LibreOffice can be encrypted. I have also used Truecrypt. It seems a different approach is needed, thanks, Neil -- The Mailing List for the Devon & Cornwall LUG http://mailman.dclug.org.uk/listinfo/list FAQ: http://www.dcglug.org.uk/listfaq