"After you copy a file into secure storage, or create an encrypted version of it, you absolutely need to wipe the unencrypted original. Just deleting it isn't sufficient, even if you bypass the Recycle Bin, because the data still exists on disk, and data recovery utilities can often get it back.
Some encryption products avoid this problem by encrypting the file in place, literally overwriting it on disk with an encrypted version. It's more common, though, to offer secure deletion as an option. If you choose a product that lacks this feature, you should find a free secure deletion tool to use along with it".
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