Custom scheme file format

BCWipe provides an option to define custom user wiping schemes. If none of the built in schemes satisfy your security and/or speed preferences you can define your own and tell BCWipe to use it instead. Custom scheme is described in an ordinary text file using the syntax described in this section.

Custom scheme discription should start with the scheme name in square brackets:

[Scheme name]

Following the scheme name are pass definitions, single pass at each new line in the following format:

number. {random|complementary|zero|test|[hex[,hex[,hex[,hex]]]] [, verify]}

This means that each pass definition should start with its number followed by a period and a space. Next one of the pass type names should follow:

• zero - fill the file with zeroes
• test - after this pass a number of each sector of the file will be written to the beginning of this sector
• byte pattern - up to four bytes can be specified here in hexidecimal notation separated by commas. File will be overwritten with this pattern repeated over and over again until the end of file.
• random - fill the file with randomly generated data
• complementary - use the previous pass definition and fill the file with byte pattern complementary to the previous pass. For example if previous pass fills file with zeroes than a complementary to it will fill the file with all ones. Complementary to random will produce exact same random pattern inverted bit by bit. If this is the first pass in scheme definition then a stream of zeroes will be produced.

If verify is specified separated by comma at the end of the pass definition then the results of this pass will be verified before beginning the next pass. To verify the results of the pass BCWipe will generate all required data again and check if it matches with what was written to the file. Verification of all passes that request it can be turned on or off with perform verification option in BCWipe Wiping Preferences.

Examples

This custom scheme is called Custom 1 and it defines 5 passes:

• pass 1: random data pass
• pass 2: complementary to the previous (random) with verification
• pass 3: use 3-byte pattern
• pass 4: fiil file with zeroes
• pass 5: fill each file sector with its sector number and verify

[Custom 1]
1. random
2. complementary, verify
3. 0x11, 0xAA, 0x55
4. zero
5. test, verify

See also:

Wiping Preferences
Appendix A: Build in wiping schemes