What is the EFSTMPWP folder
Cipher.exe is a built-in command line tool in the Windows operating system that can be used to encrypt or decrypt data on NTFS drives. This tool also lets to securely delete data by overwriting it. When you use this built-in tool, it creates a temporary folder named EFSTMPWP on the system partition. It then more temporary files in that folder, and writes random data comprising of 0’s, 1’s and other random numbers to those files. Once the operation is completed successfully, Cipher will delete this folder. But if for some reason, the operation is interrupted, this folder may remain undeleted. If you find that the folder size has increased, you may safely delete this EFSTMPWP folder.
Does cipher permanently delete files?
When the cipher command-line tool is used with the /w switch, then Windows will wipe the file securely, so it cannot be recovered. It overwrites the unallocated space three times, to ensure it is completely wiped out.
How long does cipher /w take?
Cipher is relatively slow as it overwrites three times. A single file could take up to 15 minutes or a large hard drive could even take up to a day! Hope you find this small bit of information useful.