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As far as bit patterns go, is executable code random?
mhayes@infomatch.com
It's better for us if you don't understand
It's better for me if you don't understand
-Tragically HipAn entity claiming to be Murray Hayes wrote: : : : As far as bit patterns go, is executable code random? : : mhayes@infomatch.com : : It's better for us if you don't understand : It's better for me if you don't understand : -Tragically Hip : Nope, any executable has the same text-data-stack structure. Within the text segment, all instructions are (usually) of the same size with one to four possible formats. Consider that every instruction will begin with one of ~128 opcodes, operands are pretty predictable depending on the opcode's associated format. Any references to symbol and literal tables are within a predictable range, and the format of these tables is fixed. An assembled/linked program is going to be very far from random, same basic patterns are used for I/O, subroutine calls, iterative loops, etc. I would assume that the entropy of an executable binary is extremely low. mark -- [] Mark Rogaski [] wendigo@pobox.com [] http://www.pobox.com/~wendigo/ [] >> finger for PGP pubkey <<
"Murray Hayes" <mhayes@infomatch.com> writes: > As far as bit patterns go, is executable code random? No - it's very much not random in the sense that given just a few bytes one often has a pretty good idea of what the next byte would be. --- Dr.Dimitri Vulis KOTM Brighton Beach Boardwalk BBS, Forest Hills, N.Y.: +1-718-261-2013, 14.4Kbps
Murray Hayes wrote: > As far as bit patterns go, is executable code random? Bit patterns will vary *widely* in executable code. Some executable code will contain patterns that will probably be instantly recognizable to persons who know what to look for. If you have the right statistics software and know how to use it, you could evaluate some of those executables, but what it would tell you would depend on your interpretive ability. I have a question (or suggestion): If you have access to a full-screen browser, which can fill the entire screen with text (i.e., you can eliminate any status lines, etc.), why not do some bit dumps into an ASCII file that contains just "1"'s and "0"'s, and then view the file by holding down the down-arrow or page- down key (assuming a fast enough cursor speed)? The file would look something like this: 10101110000010101101000101101 but would fill the entire screen, and by scrolling through it, it seems you would notice any obvious bit patterns. Just a thought....
>As far as bit patterns go, is executable code random? No. It's very ordered, actually. Tom
Murray Hayes wrote: > > As far as bit patterns go, is executable code random? no. far from it. > > mhayes@infomatch.com > > It's better for us if you don't understand > It's better for me if you don't understand > -Tragically Hip
please put me off the list On Mon, 11 Nov 1996, Murray Hayes wrote: > > As far as bit patterns go, is executable code random? > > mhayes@infomatch.com > > It's better for us if you don't understand > It's better for me if you don't understand > -Tragically Hip > >