FlareOn Task 9

notes.cpp

int __fastcall encrypt_file_content_and_save_keys(FILE *out_file, FILE *in_file)
{
  __int64 v4; // rcx
  _DWORD *v5; // rdi
  __int128 *_key; // rdi
  __int64 i; // rcx
  _QWORD key_out_buf[17]; // [rsp+20h] [rbp+0h] BYREF
  __int128 key[2]; // [rsp+A8h] [rbp+88h] BYREF
  __int128 nonce[9]; // [rsp+C8h] [rbp+A8h] BYREF

  v4 = 34i64;
  v5 = key_out_buf;
  while ( v4 )
  {
    *v5++ = 0;
    --v4;
  }
  _key = key;
  for ( i = 34i64; i; --i )
  {
    *(_DWORD *)_key = 0;
    _key = (__int128 *)((char *)_key + 4);
  }
  SystemFunction036(key, 32u);
  SystemFunction036((char *)nonce + 4, 12u);
  chacha_encrypt(out_file, in_file, key, nonce);
  protect_by_assymetric_crypt(key_out_buf, key, RSA_d, RSA_n);
  print_in_hex_to_file(out_file, RSA_master_public_key);
  putc(10, out_file);
  print_in_hex_to_file(out_file, RSA_n);
  putc(10, out_file);
  print_in_hex_to_file(out_file, RSA_protected_gen_priv_key);
  putc(10, out_file);
  print_in_hex_to_file(out_file, key_out_buf);  // protected ChaCha key
  return putc(10, out_file);
}

__int64 init_stuff()
{
  __int64 rsa_p[17]; // [rsp+30h] [rbp-348h] BYREF
  __int64 rsa_q[17]; // [rsp+B8h] [rbp-2C0h] BYREF
  __int64 buf1_sub1[17]; // [rsp+140h] [rbp-238h] BYREF
  __int64 buf2_sub1[17]; // [rsp+1C8h] [rbp-1B0h] BYREF
  __int64 rsa_euler[17]; // [rsp+250h] [rbp-128h] BYREF
  char RSA_generated_private[160]; // [rsp+2D8h] [rbp-A0h] BYREF

  do
    generate_random_buf(rsa_p);
  while ( !(unsigned int)is_prime((unsigned __int64 *)rsa_p) );

  do
    generate_random_buf(rsa_q);
  while ( !(unsigned int)is_prime((unsigned __int64 *)rsa_q) );

  bignum_mul(RSA_n, (unsigned __int64 *)rsa_p, (unsigned __int64 *)rsa_q);
  calc_sub1((unsigned __int64 *)buf1_sub1, (unsigned __int64 *)rsa_p);
  calc_sub1((unsigned __int64 *)buf2_sub1, (unsigned __int64 *)rsa_q);
  bignum_mul(rsa_euler, (unsigned __int64 *)buf1_sub1, (unsigned __int64 *)buf2_sub1);

  calculate_d(RSA_d, RSA_d, rsa_euler);
  return protect_by_assymetric_crypt(
           RSA_protected_gen_priv_key,
           RSA_generated_private,
           &g_SomeConts,
           RSA_master_public_key);
}