8.6. “QR9”: RUBIK’S CUBE INSPIRED AMATEUR CRYPTO-ALGORITHM
.text:005410F3 push esi ; loop 2 counter
.text:005410F4 push edi ; loop 1 counter
.text:005410F5 push ebp ; arg_0
.text:005410F6 call get_bit
.text:005410FB add esp, 0Ch
.text:005410FE mov [ebx+esi], al ; store to internal array
.text:00541101 inc esi ; increment loop 1 counter
.text:00541102 cmp esi, 8
.text:00541105 jl short loc_5410F3
.text:00541107 inc edi ; increment loop 2 counter
.text:00541108 add ebx, 8
.text:0054110B cmp edi, 8
.text:0054110E jl short loc_5410F1
.text:00541110 lea ebx, [esp+50h+internal_array_64]
.text:00541114 mov edi, 7 ; loop 1 counter is initial state 7
.text:00541119
.text:00541119 loc_541119:
.text:00541119 xor esi, esi ; loop 2 counter
.text:0054111B
.text:0054111B loc_54111B:
.text:0054111B mov al, [ebx+esi] ; get byte from internal array
.text:0054111E push eax
.text:0054111F push edi ; loop 1 counter
.text:00541120 push esi ; loop 2 counter
.text:00541121 push ebp ; arg_0
.text:00541122 call set_bit
.text:00541127 add esp, 10h
.text:0054112A inc esi ; increment loop 2 counter
.text:0054112B cmp esi, 8
.text:0054112E jl short loc_54111B
.text:00541130 dec edi ; decrement loop 2 counter
.text:00541131 add ebx, 8
.text:00541134 cmp edi, 0FFFFFFFFh
.text:00541137 jg short loc_541119
.text:00541139 pop edi
.text:0054113A pop esi
.text:0054113B pop ebp
.text:0054113C pop ebx
.text:0054113D add esp, 40h
.text:00541140 retn
.text:00541140 rotate2 endp
It isalmostthe same, except the order of the arguments of theget_bit()andset_bit()is different.
Let’s rewrite it in C-like code:
void rotate2 (int v)
{
bool tmp[8][8]; // internal array
int i, j;
for (i=0; i<8; i++)
for (j=0; j<8; j++)
tmp[i][j]=get_bit (v, i, j);for (i=0; i<8; i++)
for (j=0; j<8; j++)
set_bit (v, j, 7-i, tmp[i][j]);
};
Let’s also rewrite therotate3()function:
void rotate3 (int v)
{
bool tmp[8][8];
int i, j;
for (i=0; i<8; i++)
for (j=0; j<8; j++)
tmp[i][j]=get_bit (i, v, j);