which one should i use as i want to clear my entire harddrive of data as im selling my current pc. the choices i have are.
US DOD (3 passes)
A high security 3 pass sanitize method, adheres to the U.S. Department of Defense standards (DOD 5220.22-M). The method is implemented as described below: 1. Randomly generated character A; 2. Complement of character A; 3. Randomly generated data stream.
security level: high
stops software recovery unerase: yes
stops hardware recovery: yes
works with compressed drives: yes
US DOD Enhanced (7 passes)
A high security (and slower) 7 pass sanitize method, adheres to the U.S. Department of Defense standards (DOD 5220.22-M). The method is implemented as described below: 1. Randomly generated character A; 2. Complement of character A; 3. Randomly generated data stream 4. Randomly generated character B; 5. Randomly generated character C; 6. Complement of character C; 7. Randomly generated data stream
security level: high
stops software recovery unerase: yes
stops hardware recovery: yes
works with compressed drives: yes
B.schneier's algorithm (7 passes)
Brouce Schneier offers seven pass overwriting algorithm in his Applied Cryptography book. First pass overwrites all disk data with 0xFF patterns, second pass with 0x00 patterns, and then five times with a cryptographically secure pseudo-random sequence.
3+7+3 beyond DOD standards
A secure (but slower) 13 pass wipe method, exceeding the U.S. Department of Defense (DoD) standards. The first 3 passes are with random patterns, the next 7 passes are the standard passes from the DoD standard and the last 3 passes are with random patterns. The last pass is checked. It can be used to wipe data on compressed drives.
security level: high
stops software recovery unerase: yes
stops hardware recovery: yes
works with compressed drives: yes
stop hardware recovery (gutmann)
A maximum security (but slow) 35 pass sanitize method, based on Peter Gutmann's paper "Secure Deletion of Data from Magnetic and Solid-State Memory". The method is designed to erase data regardless of the disk raw encoding. It effectively removes the magnetic remnants from disk, preventing hardware recovery tools from restoring any data. NOTE: This method stops both software and hardware recovery tools.
security level: high
stops software recovery unerase: yes
stops hardware recovery: yes
works with compressed drives: yes