Cleaned up incorrect definition of alphanumeric code, added defintion of printable code. Added explanation why alphanumeric code was created. Removed link to cracker, replaced with hacker.
In [[BSCS]] the alphanumeric characte have meaning: "a"-"z", "A"-"Z", "0"-"9". No special characters are included.
More specifically, in computer underground terminology, alphanumeric code is [[machine code]] that is written so that it assembles into entirely readablealphanumeric [[ASCII]] characters such as "a"0-"z"9, "A"-"Z","1"and a-"9"z. This type of encoding was created by [[Hacker (computer security)|hackers]] to be able to pass machine code through a filter that removes any non-alphanumeric character and still be able to have it perform it's intended tasks succesfully. (Because normal machine code frequently uses non-alphanumeric characters, "#"these would get removed by such a filter and the code would not be able to pass the filter without being modified to the point where it no longer works). A slightly less restrictive form of this type of encoding is printable code, "!"which uses all [[Control character|printable]] characters such as 0-9, "@"A-Z, anda-z, so!@#%^&*() onetc...
Writing alphanumeric or printable code requires a good understanding of the [[instruction set architecture]] of the machine on which the code is to be executed.
This code is used by [[cracker (computing)|cracker]]s with the intent of fooling applications, such as [[HTML form|Web forms]], into accepting [[exploit (computer science)|exploit]] code ("[[shellcode]]"). Typically, such exploits involve [[buffer overflow]]s.
Sometimes, alphanumeric code could also be used when the programmer needs to write a program but has access only to a [[text editor]] — no [[compiler]], [[assembly language|assembler]], or [[hex editor]].
