FIGURE 20 is an expansion of finalizing
a fragment heap, step 1870.
Normally, step 2010 is to pad the
unused zero to 15 bytes at the end of the designated fragment heap 1651
with random bytes out to 65,536 bytes. In the event that all data has been
used and there will be no further fragments, 0 to 1,023 random bytes are
added, exactly enough to convert the fragment heap 1651 into a composite
segment 1652 whose active size is a multiple of 1,024 bytes.
Step 2020 is to apply camouflage to the
composite segment 1652. The purpose is to remove any possibility of
patterns appearing within a composite segment 1652 of a composite file
0250. An action code 91 (1591) series of exclusive OR operations is
executed for some random number of steps starting at a random point in the
currently active section of the random table buffer 1630. See 1591 action
step 91 for detail and also see "HandleFragFiles.cpp" in the appendix for
an implementation. The camouflage buffer 1680 is used as a source of bytes
for exclusive OR operations in random patterns across the composite segment
1652. An action code 91 is recorded with its beginning and terminating
offsets within the currently active section of the random table buffer
1630.
Step 2030 involves writing an action
code 21 (1521) to indicate closure of the composite segment 1652. The first
three trailer items -- two byte size of the composite segment 1652 in bytes
prior to random padding, one byte value 0 ... 119 which specifies the
composite file 0250 to which the composite segment 1652 is written, and a
one byte value 0 ... 15 which specifies the fragment heap 1651 from which
the composite segment 1652 was created.
Step 2040 is to write a dummy action
code 22 with the fourth trailer for action code 21 (1521), the offset in
multiples of 1,024 at which the composite segment 1652 begins within the
composite file 0250. Action code 22 is needed during fragmentation 1740
because at this stage the trailer width is fixed at four bytes. This
restriction is lifted later when the reconstitution plan 1270 is created in
steps 2130 and 2140.
