High Quality Content by WIKIPEDIA articles! On-the-fly encryption (OTFE), also known as Real-time Encryption, is a method used by some encryption programs, for example, disk encryption software. "On-the-fly" refers to the fact that the files are accessible immediately after the key is provided, and the entire volume is typically mounted as if it were a physical drive, making the files just as accessible as any unencrypted ones. To be transparent to the end user, on-the-fly encryption requires the use of device drivers to enable the encryption process. Although administrator access rights are normally required to install such drivers, encrypted volumes can typically be used by normal users without these rights.