Wiping and Initializing
To securely erase (shred) data in disk sectors, unused disk areas (Disk Tools menu), or files selected with the Wipe Securely command, and also simply to fill files with certain byte values, WinHex offers the following options:
With constant byte values specified in hexadecimal notation: Specify either 1, 2, 3, 4, 5, 6, 12, 15, or 16 two-character hex values, which will be copied repeatedly into the current block, the entire file or all disk sectors, respectively. Very fast.
With simple pseudo-random byte values: Specify a decimal interval (0 to 255 at max.) for random numbers, which will be copied repeatedly into the current block, the entire file or all disk sectors, respectively. The random bytes are Laplace-distributed. Fast.
With pseudo-random data that simulates encryption: Random data that is supposed to be indistinguishable from encrypted data. Quite fast.
With cryptographically sound pseudo-random data: Cryptographically secure pseudo-random number generator (CSPRNG) called ISAAC, very slow.
In case in all open files either a block or no block is defined, this command can optionally be applied to all these files at the same time.
To maximize security, if you wish to totally wipe (sanitize) slack space, free space, unused NTFS records, or an entire media, you may want to apply more than one pass for overwriting disk space (up to three).
According to the Clearing and Sanitization Matrix, the standard outlined in the U.S. Department of Defense (DoD) 5220.22-M operating manual, method "c", a hard disk or floppy disk can be cleared by overwriting (once) all addressable locations with a single character. This is usually the hexadecimal value 0x00, but can be any other value. To sanitize hard disks according to method "d", overwrite all addressable locations with a character, its complement, then a random character, and verify. (This method is not approved by the DoD for sanitizing media that contain top secret information.)
The "DoD" button configures WinHex for sanitization, such that it will first overwrite with 0x55 (binary 01010101), then with its complement (0xAA = 10101010), and finally with random byte values.
The "0x00" button configures WinHex for simple initialization, wiping once with zero bytes.