I cant figure out how this function decyphers a 6 letter string.
Code:void cypher_5(long param_1) { int iVar1; int iVar2; iVar1 = string_length(); if (iVar1 != 6) { printf("error"); } iVar2 = 0; iVar1 = 0; while (iVar1 < 6) { iVar2 = iVar2 + *(int *)(array.3597 + (ulong)((uint)*(byte *)(param_1 + iVar1) & 0xf) * 4); iVar1 = iVar1 + 1; } if (iVar2 != 0x31) { printf("error"); } return; }
I suggest that you post a compilable program rather than just a fragment with unexplained parts. I can make guesses based on what I see, but why guess when you can post the definitions of param_1 and array.3597? Or string_length, for that matter.
Last edited by laserlight; 11-20-2019 at 12:35 AM.
Look up a C++ Reference and learn How To Ask Questions The Smart WayOriginally Posted by Bjarne Stroustrup (2000-10-14)
unfortunately this is reversed engenieered code,i only have access to the code in assembly and used ghidra to get the source code in C.
It's not "decyphering" anything. It's calculating a sum and then complaining if it's not 0x31.
With some assumptions, I think the code is better expressed like this (I've given variables somewhat arbitrary names, particularly "table").
Code:#include <stdio.h> typedef unsigned char byte; typedef unsigned int uint; typedef unsigned long ulong; int array[64] = {1, 2, 3, 4, 5, 6, 7, 8, 9}; byte table[] = {0, 1, 2, 3, 4, 5}; void cypher_5(byte *tab) { //if (string_length() != 6) printf("error\n"); int sum = 0; for (int i = 0; i < 6; ++i) sum += array[ (uint)tab[i] & 0xf ]; // sum += *(int*)(array + // this is assuming array is a byte array // (ulong)( (uint)*(byte*)(tab + i) & 0xf ) * 4 // ); printf("%d\n", (int)sum); if (sum != 0x31) printf("error\n"); } int main() { cypher_5(table); }
A little inaccuracy saves tons of explanation. - H.H. Munro
