findHash.py - Locate 4k fragments of a subject file in one or more other
files or devices.

Usage:
    findHash.py /path/to/subject {/dev/sdX|/path/to/image} [/dev/sdY ...]

The subject file is read 4k at a time, and each 4k block is hashed and
recorded in a dictionary.  Any tail fragment less than 4k is discarded.

The each device or image file is read in turn, 4k at a time.  Each 4k
block is hashed and looked up in the subject's hash dictionary.  Where
consecutive 4k blocks in a device or image file match consecutive 4k blocks
in the subject file, the matches are printed with the corresponding
offset information.