Easy Risky solution - ASIS CTF 2023

solve.c

#include <stdint.h>
#include <stdio.h>

void encryptData(uint8_t *flag_enc) {
    uint8_t bVar1;
    int64_t lVar2;
    uint64_t *puVar3;
    uint64_t uVar4;
    uint8_t *pbVar5;
    uint64_t uVar6;
    uint64_t uVar7;

  if (flag_enc[0x2a] != 0) {
    return;
  }
  uVar6 = -(long)flag_enc;
  uVar7 = uVar6 & 7;
  if (uVar7 == 0) {
    uVar4 = (uint64_t)flag_enc[0x2b];
    lVar2 = 0x2a;
    pbVar5 = flag_enc;
  }
  else {
    bVar1 = flag_enc[0x2b];
    uVar4 = (uint64_t)bVar1;
    *flag_enc = *flag_enc ^ bVar1;
    if ((uVar6 & 6) == 0) {
      lVar2 = 0x29;
      pbVar5 = flag_enc + 1;
    }
    else {
      lVar2 = 0x28;
      flag_enc[1] = flag_enc[1] ^ bVar1;
      pbVar5 = flag_enc + 2;
      if (2 < uVar7) {
        lVar2 = 0x27;
        flag_enc[2] = flag_enc[2] ^ bVar1;
        pbVar5 = flag_enc + 3;
        if ((uVar6 & 4) != 0) {
          flag_enc[3] = flag_enc[3] ^ bVar1;
          if (uVar7 < 5) {
            lVar2 = 0x26;
            pbVar5 = flag_enc + 4;
          }
          else {
            flag_enc[4] = flag_enc[4] ^ bVar1;
            if (uVar7 == 5) {
              lVar2 = 0x25;
              pbVar5 = flag_enc + 5;
            }
            else {
              flag_enc[5] = flag_enc[5] ^ bVar1;
              lVar2 = 0x24;
              pbVar5 = flag_enc + 6;
              if (((uint64_t)(flag_enc + -1) & 7) == 0) {
                lVar2 = 0x23;
                flag_enc[6] = flag_enc[6] ^ bVar1;
                pbVar5 = flag_enc + 7;
              }
            }
          }
        }
      }
    }
  }
  puVar3 = (uint64_t *)(flag_enc + uVar7);
  uVar6 = uVar4 << 8 | uVar4 | uVar4 << 0x10 | uVar4 << 0x18 | uVar4 << 0x20 | uVar4 << 0x28 |
          uVar4 << 0x30 | uVar4 << 0x38;
  puVar3[3] = uVar6 ^ puVar3[3];
  *puVar3 = uVar6 ^ *puVar3;
  puVar3[1] = uVar6 ^ puVar3[1];
  puVar3[2] = uVar6 ^ puVar3[2];
  if (0x2a - uVar7 >> 3 == 5) {
    pbVar5 = pbVar5 + 0x28;
    puVar3[4] = uVar6 ^ puVar3[4];
    lVar2 = lVar2 + -0x28;
    if (0x2a - uVar7 == 0x28) goto LAB_00100c04;
  }
  else {
    pbVar5 = pbVar5 + 0x20;
    lVar2 = lVar2 + -0x20;
  }
  *pbVar5 = *pbVar5 ^ flag_enc[0x2b];
  if ((((lVar2 != 1) && (pbVar5[1] = pbVar5[1] ^ flag_enc[0x2b], lVar2 != 2)) &&
      (pbVar5[2] = pbVar5[2] ^ flag_enc[0x2b], lVar2 != 3)) &&
     (((pbVar5[3] = pbVar5[3] ^ flag_enc[0x2b], lVar2 != 4 &&
       (pbVar5[4] = pbVar5[4] ^ flag_enc[0x2b], lVar2 != 5)) &&
      (pbVar5[5] = pbVar5[5] ^ flag_enc[0x2b], lVar2 != 6)))) {
    pbVar5[6] = pbVar5[6] ^ flag_enc[0x2b];
  }
LAB_00100c04:
  flag_enc[0x2a] = 1;
  return;
}

void main() {
        char enc_flag[] = { 0x6b,0x79,0x63,0x79,0x51,0x1d,0x58,0x73,0x75,0x5e,0x65,0x75,0x58,0x7f,0x44,0x75,0x67,0x19,0x75,0x45,0x64,0x75,0x78,0x63,0x79,0x69,0x07,0x7c,0x1c,0x1e,0x75,0x47,0x1e,0x49,0x62,0x0b,0x44,0x6f,0x0b,0x0b,0x57,0x2a,0x00,0x2a};
        encryptData(enc_flag);
        puts(enc_flag);
}