bitflipper

This command-line utility flips (turns 1 into 0 and vice versa) a specified amount of randomly chosen bits in any file.

Installation

Compile main.c.

Usage

Arguments

• -n, --amount <number> set amount of bits to flip in a file. 0 if not provided.
• -s, --seed <number> sets the seed for random generator. Random generator is responsible for picking the bits to flip. 0 if not provided.
• -s, --seed time sets the seed from current system time.
• -h, --help shows the help message.
• -v, --verbose enables verbose mode.
• --disk write changes to the disk immediately as they happen.
• --ram make changes in the RAM copy of the file, then rewrite the file once with modified data.
• --skip <number> amount of bytes from the beginning of the file the bitflipper will not affect.

Examples

bitflipper ./image.bmp -n 1000 -stime

This will flip 1000 bits in the file 'image.bmp' with a different seed each time it's executed.

Interesting behavior can be seen if a command is executed twice with the same seed and number of bits:

bitflipper ./image2.bmp -n 10000 -s 1234

On the first execution the file is going to get partially or fully corrupted, but on the second run the file is going to return to it's initial state, since the bits flipped are going to be exactly the same as before. This essentially decrypts the file. Note that this may not work across different operating sytems due to different rand() implementations.

bitflipper --skip 54 ./image3.bmp -vn1000000 -stime --ram

This will enable verbose mode, set seed from current time, make 1000000 bit flips and then write the changes to the drive. Note that BMP header will not be affected.