Eureka Encryption Library Help
Other Features
Expansion
Expansion regards the hiding of the encrypted data into a sea of data. Each
encrypted character is followed by a random number of encrypted worthless
characters. The number of padding change for each byte in a truly random fashion
so attacking this data will yield far more difficulties in the attack than
in a straight data encryption.
When you generate the cryptive files needed by the use of the EurGenBinaryKeys
or EurGenTextKeys, a series of keys are generated for this purpose. Whenever you
call one of the Expand routines, these keys are applied to the expansion.
You can expect the size of the encrypted files to be several times larger than
the data file, so expect longer processing time for larger files.
Scrambling
Scrambling was included as an aid for disgusing an encrypted file even more. There
are two kinds of scrambling; a ratio type and a random type.
Here's how the basic scramble process works. Each block will read a certain
number of characters. That string of characters are reversed or mirrored and
then written to another file, or rewritten to the existing file at that
position.
The two calls are EurScrambleFile (ratio) and EurXScrambleFile (random). See
the Procedures section for call structure and examples on calling them. For
now, let us look at some considerations regarding the calls.
EurScrambleFile
The ratio style will use fixed record blocks (bytes) of data. You supply the
number of blocks and the blocksize to process. You may need to use the LOF()
function or other means to retrieve the filesize of the file you want to
scramble so you will not request more bytes than the file contains.
Let us assume you have a file with 500 bytes. You could scramble it like the
following:
5 Blocks, blocksize 100 (each 100 byte string will be reversed for the entire file)
10 Blocks, blocksize 50 (each 50 byte string will be reversed for the entire file)
25 Blocks, blocksize 10 (each 10 byte string will be reversed for twenty-five times)
Note that the third example will only scamble the first 250 bytes, leaving the
remaining bytes unscrambled.
EurXScramble
The random style is far superior. A table will be generated based on the files
created when you perform a EurGenBinaryKeys or EurGenTextKeys call. Each number
in the table will determine the number of bytes to scramble within the file in
sequence. This will continue for the entire file.
For an example, if the table generated produced the following numbers in the
table 3,12,6,44 etc. then the following would occur:
03 - File position 01: first three bytes are mirrored.
12 - File position 04: next 12 bytes are mirrored.
06 - File position 16: next 6 bytes are mirrored.
44 - File position 22: next 44 bytes are mirrored.
and so on...
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