Methods of protection code
Review article
To date, the image do a few methods to protect software
code. Enumerate them.
1.Zaschita inverting the mask.
(In the hoi polloi - KSORKA)
Widely known and used method.
Often used with the application of quality space in the mask
register R and is characterized by Ed Kim monotony, though
occasionally getting this program are masterpieces. Ma
loeffektiven, although they often require no little time for
hacking. Shining example use: copier L-Copy (AB torus: Laptev).
2.Zaschita with different "perverted".
"Distorted" - code that is written with the use of specially
complicated algorithms with to hide the direct address or
launch a sub or entangling itself program. Different to
lichestvom unlimited options, but uses relatively rare,
because designed to poor knowledge of assembler and principles
programming. Currently, small loeffektiven. Examples of common
daily activities locally, such as: the machinations of the
stack, conditional jumps and "implicit" exit
through the stack at the correct address.
3.Metod using the PI code, or just
novidnostey threaded code.
PI code - assembler for an abstract ma bus, a sort of
intermediate stage between machine code and high-level
language. Threaded code - a specific version of the same PI
code.
Very cool method of protection, in general, on hozhy on method
2, but only rarely applicable to the class PC Spectrum. Not
wealth: "not weak" code size and more lower than the "pure"
code bystrodeys tvie. Effectiveness of the method is very high
and breaking of the teeth only very experienced programmers.
Example: Any program compiled in Pascal language Forth.
At such a code can Spectrum'e generating vat compiler BLAST
(the rest is generated ruyut "perverted", supra).
4.Metod using kriptografiches
FIR algorithms and passwords.
Widely used in powerful PCs and
different spyware "offices" method. Based on the van on a
variety of mathematical algorithms for the FIR, the purpose of
which - by macabre calculations obtained from the source
information block and a key Massie Islands (password), a file,
decode which can only be one who has this
password. Hack a file can only be
after studying forty pounds of a special mathematical
literature, after then you can safely offer their
candidature for the post of CIA director.
At Spectrum'e not effective because Password
none but ourselves can not show,
another couple of days later he learns all the
country.
5.Metod which is based on IM2.
In contrast to the above I do not
caught, so that explains the speculative but. Based on
"linking" the main prog Ramm and ISR (from the English .-
"routine of processing interrupts" - Interrupt Service
Routine) to organize the control (For example, assume the
checksum) main program for infringing ments outside. Then
opens wide field experiments. You can, for examples py,
organize data transmission through ISR data from one array to
another
or use the ISR for the dynamic
encoding unused for the current
time routines, etc. Complexity method in appropriate depth of
the and "matching" algorithms and ISR programs,
to avoid the bugs and delays in work
program because of aperiodic ISR,
related to the complexity of determining time to time interval
from DI EI. Very promising and promising method.
It seems that all other options
protection of software code are nothing more than special cases
of the above or combinations thereof. Use of undocumented
commands Z80 is not included in the article because of the
trivial - The last time they actually are well known to all.
I will be glad of any information on how to
information security and cooperation in this
area.
Spinel Roman E. (SHRSOFT).
