Common Assembly commands for software cracking

Cmp a, B // compare A and B
MoV A, B // send the value of B to the value of a, so that a = B
RET // return the main program
NOP // no effect, abbreviated as "do nothing" (machine code 90)
(Ultraedit open and edit the EXE file to see the NOP of 90 equivalent Assembly statements)
Call // call a subroutine ending with RET
Je or JZ // equal jump (machine code 74 or 84)
JNE or jnz // skip if not equal (machine code is 75 or 85)
JMP // unconditional jump (machine code is EB)
JB // skip if the value is smaller
Ja // skip if the value is greater
JG // skip if the value is greater
Jge // skip if the value is greater than or equal
Jl // skip if the value is smaller
Pop XXX // XXX output Stack
Push XXX // XXX pressure Stack

Brute force cracking

One (HOP) will die, and nine (90) will be hu-(corresponding to 2 above -- changed to NOP)
One (HOP) is Hu, one (EB) is waiting-(corresponding to 1 above -- changed to JMP)
(74) Change (75)
(84) Change (85)

One (HOP) will die, and nine (90) will be Hu

The software code corresponding to this phrase has the characteristic that the Code after the jump command is the code that the software runs normally, and the jump command jumps to the Abnormal Running code such as software restrictions.

It means that if the software fails to be registered after the jump (jump to the Specified Code) (unavailable, functional restrictions, etc ), change the jump command (for example, the JMP machine code is EB) to NOP (the machine code is 90). After this change, the jump command becomes invalid, so that the code behind the jump command can be executed, achieve the purpose of brute force cracking software.

One (HOP), one (EB)

The software code corresponding to this phrase has the following characteristics: the code that reaches the normal running of the software after the jump, rather than the jump, run the Abnormal Running code below the jump command (for example, the Code cannot be registered or the function is restricted ).

It means that if the software runs normally after the jump (jump to the Specified Code) (such as successful registration and function restriction relief ), so we need to turn this jump into the unconditional jump command JMP (machine code is EB) to crack the attack.